Neuropathic features of joint pain: a community-based study

The number of central nervous system-driven symptoms predicts subsequent chronic primary pain: evidence from UK Biobank

BACKGROUND

Chronic primary pain describes conditions where pain is the principal problem rather than a consequence of another disease. Primary pain is thought to be primarily owing to nociplastic pain (i.e. pain as a result of altered nociception despite the absence of tissue damage). Primary pain is often accompanied by other bothersome central nervous system (CNS)-driven symptoms, including disturbed sleep, mood, and cognition; however, it is unclear whether these symptoms precede onset of primary pain.

METHODS

In a prospective cohort study of the UK Biobank, we examined adults with no self-reported recent or chronic pain at baseline. Using linked primary care record data, we investigated the association between the number of CNS-driven symptoms and subsequent incidence of primary pain conditions. Multivariable regression analyses adjusted for sociodemographic and lifestyle factors.

RESULTS

Of 502 369 participants, 70 630 (14.0%) met the inclusion criteria, with a mean (range) age of 56.7 (40-70) yr, 51% being female. After 7.4 (range 0.5-11.02) yr, 12.2% developed a primary pain condition. We observed a positive relationship between the number of CNS-driven symptoms at baseline and risk of future primary pain (HR 1.43, 95% CI 1.34-1.52, P<0.001). Participants with more CNS-driven symptoms at baseline were also more likely to have chronic and more severe nociplastic pain, but not non-nociplastic pain at follow-up.

CONCLUSIONS

In adults with no current self-reported pain, those with a greater number of CNS-driven symptoms at baseline were more likely to develop a primary pain condition. This suggests a potential opportunity for early intervention in mitigating the burden of primary pain.

Neuropathic pain is a feature in patients with symptomatic femoral acetabular impingement

Femoral acetabular impingement syndrome (FAIS) is a cause of hip pain thought to be nociceptive, although pain phenotypes e.g., burning, pain attacks, prickling, numbness etc., are reported, mimicking neuropathic pain. Although no lesion to the somatosensory system is identified, neuropathic pain (NeP) may explain why nociceptive-focussed treatments are not always successful.

OBJECTIVE

To identify NeP in patients with FAIS and investigate if related to poorer outcomes.

DESIGN

A secondary analysis of the Femoral Acetabular Impingement Trial (FAIT). Outcome of interest: PainDETECT questionnaire; secondary outcomes of interest; International Hip Outcome Tool (iHOT33), Hospital Anxiety and Depression Scale (HADS) and VAS 'average pain over a month', at baseline and 8 months follow-up. Intervention (surgery or physiotherapy) were pooled.

RESULTS

173 data sets at baseline; 123 at 8 months follow-up. Baseline painDETECT identified three groups: 69% nociceptive, 19% unclear and 12% neuropathic pain phenotypes. Baseline, median scores were higher for the neuropathic group compared to the nociceptive group demonstrating borderline anxiety (9.5(5.3 to 14.2), 5(3 to 8), higher normal values for depression (7.5(2.3 to 11.8), (4(2 to 9), higher average pain (7 (6 to 8), 5(4 to 6) and lower iHOT33 14.2(9 to 21.1), 38.4(26.2 to 55.7). Post treatment, there was a median change in the neuropathic score in both iHOT33 (40.8 (25 to 76.5) with a median difference of 24.13 (CI 95% 10.46 to 45.92) and average pain 4.5(1.5 to 7) with a median difference of 2 (CI 95% 1 to 5) but to a lesser amount than the nociceptive group, iHOT33 (64(38.2 to 86.6) with a median difference of 15.50 (CI 95% 6.41 to 21.82) and average pain 3(1 to 5.7) with a median difference of 1 (CI 95% 0.5 to 1).

CONCLUSION

NeP exists in symptomatic FAIS patients and is associated with increased average pain, and functional limitations. Nociceptive-targeted treatment improves hip function and pain but with less improvement in the NeP group when compared to the nociceptive group. Pain phenotyping before intervention may improve outcomes. CONTRIBUTION OF PAPER.

Relationship Between Chronic Pain Types (Nociceptive and Neuropathic-Like Symptoms) and Frailty in Community-Dwelling Japanese Older Adults: A Cross-Sectional Study

Purpose

Chronic pain may accelerate the development of frailty in older adults through a variety of mechanisms. There are no published investigations of the influence of neuropathic-like symptoms on physical frailty. We investigated the association between chronic pain types (nociceptive and neuropathic-like symptoms) and frailty in community-dwelling Japanese older adults.

Participants and Methods

This was a population-based cross-sectional study conducted in 2017 in the city of Itoshima, Japan of 917 participants aged 65-75 years, not in need of long-term care, who had completed the physical function tests and questionnaires administered at measurement sessions held at community centers at three sites over a 1- to 2-month period. Their chronic pain types were classified as no-chronic pain, nociceptive pain, and neuropathic-like symptoms according to their painDETECT scores. Frailty phenotypes were defined by the following five components: unintentional weight loss, low grip strength, exhaustion, slow gait speed, and low physical activity. A logistic regression model was used to compute the odds ratios (ORs) and 95% confidence interval (CIs) for frailty status outcomes.

Results

The prevalence of pre-frailty was 51.9%, and that of frailty was 5.1%. In multinomial logistic regression analyses, compared to the no-chronic pain group, the OR for the presence of pre-frailty among the participants with nociceptive pain was 1.54 (95% CI: 1.04-2.30, p=0.03), and the OR for the presence of frailty among the participants with neuropathic-like symptoms was 4.37 (95% CI: 1.10-17.37, p=0.04). The neuropathic sensory symptoms of burning, tingling/prickling, and numbness were each associated with frailty, but not with the risk of pre-frailty.

Conclusion

Neuropathic-like symptoms were significantly associated with the presence of frailty in community-dwelling Japanese older adults. Chronic pain types might have different effects on frailty status.

Association between the number of chronic pain sites and neuropathic-like symptoms in community-dwelling older adults with chronic pain: a cross-sectional study

OBJECTIVES

We investigated the relationship between the number of chronic pain sites and the prevalence and severity of neuropathic-like symptoms in community-dwelling older Japanese adults with chronic pain.

DESIGN

Cross-sectional study.

SETTING

The data analysed are from a study conducted in the city of Itoshima, Japan in 2017.

PARTICIPANTS

The study population was 988 participants (age 65-75 years) not in need of long-term care who completed questionnaires assessing sociodemographic factors, psychological factors and chronic pain.

PRIMARY OUTCOME MEASURES

The primary outcome was the participants' neuropathic-like symptoms evaluated by the PainDETECT Questionnaire (PD-Q). We classified the participants into mild and moderate-to-severe pain groups according to the pain intensity on the PD-Q. The number of chronic pain sites was categorised into groups with 1, 2-3 and ≥4 sites.

RESULTS

The age-adjusted and sex-adjusted prevalence of neuropathic-like symptoms was significantly higher among the participants with 2-3 or ≥4 sites compared with the single-site group. In the binomial logistic regression analyses, the multivariable-adjusted ORs and 95% CIs for neuropathic-like symptoms among the participants with 2-3 and ≥4 sites were 1.94 (1.13 to 3.33) and 3.90 (2.22 to 6.85), respectively compared with the participants with single-site pain. The ORs for moderate-to-severe neuropathic-like symptoms increased significantly with the increase in the number of chronic pain sites.

CONCLUSIONS

The number of chronic pain sites was positively associated with the presence and severity of neuropathic-like symptoms in community-dwelling older Japanese adults with chronic pain.

Development of a Clinical Prediction Rule for Treatment Success with Transcranial Direct Current Stimulation for Knee Osteoarthritis Pain: A Secondary Analysis of a Double-Blind Randomized Controlled Trial

The study’s objective was to develop a clinical prediction rule that predicts a clinically significant analgesic effect on chronic knee osteoarthritis pain after transcranial direct current stimulation treatment. This is a secondary analysis from a double-blind randomized controlled trial. Data from 51 individuals with chronic knee osteoarthritis pain and an impaired descending pain inhibitory system were used. The intervention comprised a 15-session protocol of anodal primary motor cortex transcranial direct current stimulation. Treatment success was defined by the Western Ontario and McMaster Universities’ Osteoarthritis Index pain subscale. Accuracy statistics were calculated for each potential predictor and for the final model. The final logistic regression model was statistically significant (p < 0.01) and comprised five physical and psychosocial predictor variables that together yielded a positive likelihood ratio of 14.40 (95% CI: 3.66−56.69) and an 85% (95%CI: 60−96%) post-test probability of success. This is the first clinical prediction rule proposed for transcranial direct current stimulation in patients with chronic pain. The model underscores the importance of both physical and psychosocial factors as predictors of the analgesic response to transcranial direct current stimulation treatment. Validation of the proposed clinical prediction rule should be performed in other datasets.

Topical clonidine for neuropathic pain in adults

BACKGROUND

Clonidine is a presynaptic alpha-2-adrenergic receptor agonist that has been used for many years to treat hypertension and other conditions, including chronic pain. Adverse events associated with systemic use of the drug have limited its application. Topical use of drugs has been gaining interest since the beginning of the century, as it may limit adverse events without loss of analgesic efficacy. Topical clonidine (TC) formulations have been investigated for almost 20 years in clinical trials. This is an update of the original Cochrane Review published in Issue 8, 2015.

OBJECTIVES

The objective of this review was to assess the analgesic efficacy and safety of TC compared with placebo or other drugs in adults aged 18 years or above with chronic neuropathic pain.

SEARCH METHODS

For this update we searched the Cochrane Register of Studies Online (CRSO), MEDLINE (Ovid), and Embase (Ovid) databases, and reference lists of retrieved papers and trial registries. We also contacted experts in the field. The most recent search was performed on 27 October 2021.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing TC versus placebo or other active treatment in adults with chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened references for eligibility, extracted data, and assessed risk of bias. Any discrepancies were resolved by discussion or by consulting a third review author if necessary. Where required, we contacted trial authors to request additional information. We presented pooled estimates for dichotomous outcomes as risk ratios (RRs) with 95% confidence intervals (CIs), and continuous outcomes as mean differences (MDs) with P values. We used Review Manager Web software to perform the meta-analyses. We used a fixed-effect model if we considered heterogeneity as not important; otherwise, we used a random-effects model.  The review primary outcomes were: participant-reported pain relief of 50% or greater; participant-reported pain relief of 30% or greater; much or very much improved on Patient Global Impression of Change scale (PGIC); and very much improved on PGIC. Secondary outcomes included withdrawals due to adverse events; participants experiencing at least one adverse event; and withdrawals due to lack of efficacy. All outcomes were measured at the longest follow-up period. We assessed the certainty of evidence using GRADE and created two summary of findings tables.

MAIN RESULTS

We included four studies in the review (two new in this update), with a total of 743 participants with painful diabetic neuropathy (PDN). TC (0.1% or 0.2%) was applied in gel form to the painful area two to three times daily. The double-blind treatment phase of three studies lasted 8 weeks to 85 days and compared TC versus placebo. In the fourth study, the double-blind treatment phase lasted 12 weeks and compared TC versus topical capsaicin. We assessed the studies as at unclear or high risk of bias for most domains; all studies were at unclear risk of bias for allocation concealment and blinding of outcome assessment; one study was at high risk of bias for blinding of participants and personnel; two studies were at high risk of attrition bias; and three studies were at high risk of bias due to notable funding concerns. We judged the certainty of evidence (GRADE) to be moderate to very low, downgrading for study limitations, imprecision of results, and publication bias. TC compared to placebo There was no evidence of a difference in number of participants with participant-reported pain relief of 50% or greater during longest follow-up period (12 weeks) between groups (risk ratio (RR) 1.21, 95% confidence interval (CI) 0.78 to 1.86; 179 participants; 1 study; low certainty evidence). However, the number of participants with participant-reported pain relief of 30% or greater during longest follow-up period (8 to 12 weeks) was higher in the TC group compared with placebo (RR 1.35, 95% CI 1.03 to 1.77; 344 participants; 2 studies, very low certainty evidence). The number needed to treat for an additional beneficial outcome (NNTB) for this comparison was 8.33 (95% CI 4.3 to 50.0). Also, there was no evidence of a difference between groups for the outcomes much or very much improved on the PGIC during longest follow-up period (12 weeks) or very much improved on PGIC during the longest follow-up period (12 weeks) (RR 1.06, 95% CI 0.76 to 1.49 and RR 1.82, 95% CI 0.89 to 3.72, respectively; 179 participants; 1 study; low certainty evidence). We observed no evidence of a difference between groups in withdrawals due to adverse events and withdrawals due to lack of efficacy during the longest follow-up period (12 weeks) (RR 0.34, 95% CI 0.04 to 3.18 and RR 1.01, 95% CI 0.06 to 15.92, respectively; 179 participants; 1 study; low certainty evidence) and participants experiencing at least one adverse event during longest follow-up period (12 weeks) (RR 0.65, 95% CI 0.14 to 3.05; 344 participants; 2 studies; low certainty evidence).  TC compared to active comparator There was no evidence of a difference in the number of participants with participant-reported pain relief of 50% or greater during longest follow-up period (12 weeks) between groups (RR 1.41, 95% CI 0.99 to 2.0; 139 participants; 1 study; low certainty evidence). Other outcomes were not reported.

AUTHORS' CONCLUSIONS

This is an update of a review published in 2015, for which our conclusions remain unchanged. Topical clonidine may provide some benefit to adults with painful diabetic neuropathy; however, the evidence is very uncertain. Additional trials are needed to assess TC in other neuropathic pain conditions and to determine whether it is possible to predict who or which groups of people will benefit from TC.

Neuropathic-like Pain in Fibrous Dysplasia/McCune-Albright Syndrome

CONTEXT

Pain is a major symptom in adults with fibrous dysplasia/McCune-Albright syndrome (FD/MAS) and response to current treatments, including bisphosphonates and standard analgesics (nonsteroidal anti-inflammatory drugs and opiates) is unpredictable. No studies have explored whether the type of pain is variable in this patient group.

OBJECTIVE

To determine the frequency of neuropathic-like pain in patients with FD/MAS.

DESIGN

Retrospective, dual registry study.

SETTING

Community.

PATIENTS

FD/MAS online registries: the US-based Familial Dysautonomia Foundation (FDF) and the UK-based Rare and Undiagnosed Diseases (RUDY) study.

INTERVENTION

Subjects completed questionnaires to evaluate the presence of features of neuropathic-like pain (painDETECT) and the impact on sleep quality (Pittsburgh Sleep Quality Index) and mental health (Hospital Anxiety and Depression Scale). Descriptive statistics were used to characterize the prevalence and associated burden of neuropathic-like pain.

MAIN OUTCOME MEASURES

Incidence of neuropathic, nociceptive, and unclear pain.

RESULTS

Of 249 participants, one third experienced neuropathic-like pain. This group had statistically significantly (P < 0.001) worse mental well-being and sleep in comparison to those with predominately nociceptive pain.

CONCLUSIONS

Neuropathic-like pain is common in patients with FD/MAS and associated with worse quality of life. Evaluation of pain in patients with FD/MAS should include assessment of neuropathic-like pain to guide personalized approaches to treatment and inform future research.

Neuropathic pain is associated with poor health-related quality of life in adolescents with sickle cell disease: A preliminary report

BACKGROUND

Neuropathic pain is associated with poor health-related quality of life (HRQL) in pain conditions other than sickle cell disease (SCD); this relationship in SCD is unknown. We investigated this relationship and hypothesized neuropathic pain is associated with poor HRQL in adolescents with SCD.

METHODS

We conducted a cross-sectional study of patients with SCD ages 13-18 years during baseline health. Primary outcome was HRQL, assessed by the PedsQL SCD Module (child self-report, parent proxy report). PedsQL is scored from 0 to 100, with higher scores indicating better HRQL. Neuropathic pain was assessed using the painDETECT questionnaire (scored 0-38); higher scores indicated greater likelihood of neuropathic pain. All completed both PedsQL SCD Module and painDETECT questionnaire. Descriptive statistics were used and associations between painDETECT and PedsQL Total Score, Pain Impact, Pain and Hurt, and Pain Management and Control Scores were determined via Pearson correlation. Significance was P < .05.

RESULTS

Twelve patients were enrolled. Median (interquartile range [IQR]) age was 15 (14-16.5) years, 75% were female, and 83% were on hydroxyurea. Higher painDETECT scores were significantly associated with lower PedsQL SCD Module child self-report Pain and Hurt Scores (r = -0.68, P = .01). Higher painDETECT scores were also significantly associated with lower PedsQL parent proxy-report Total Scores (r = -0.64, P = .03) and Pain and Hurt Scores (r = -0.67, P = .02).

CONCLUSIONS

These data suggest that adolescents with SCD and neuropathic pain have poor HRQL even in their baseline state of health. Prospective, larger studies are needed to confirm this preliminary finding and explore a multimodal approach for pain assessment in SCD.

Can self-reported pain characteristics and bedside test be used for the assessment of pain mechanisms? An analysis of results of neuropathic pain questionnaires and quantitative sensory testing

Hyperalgesia and allodynia are frequent in neuropathic pain. Some pain questionnaires such as the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) and the Neuropathic Pain Scale (NPS) include self-assessment or bedside testing of hyperalgesia/allodynia. The aim of this study was to determine to what extent LANSS and NPS data are congruent with findings on quantitative sensory testing (QST). Self-reported presence of dynamic mechanical allodynia (DMA) and descriptors of hot, cold, or deep ongoing pain (the NPS and LANSS) as well as bedside findings of mechanical allodynia (LANSS) were compared with signs of DMA and thermal hyperalgesia on QST in 617 patients with neuropathic pain. Self-reported abnormal skin sensitivity (LANSS) showed a moderate concordance with DMA during bedside test (67.9%, κ = 0.391) or QST (52.8%, κ = 0.165). Receiver operating curve analysis for self-reported DMA yielded similar area-under-the-curve values for the LANSS (0.65, confidence interval: 0.59%-0.97%) and NPS (0.71, confidence interval: 0.66%-0.75%) with high sensitivity but low specificity. Self-reported deep pain intensity was higher in patients with blunt pressure hyperalgesia, but not in patients with DMA or thermal hyperalgesia. No correlations were observed between self-reported hot or cold pain quality and thermal hyperalgesia on QST. Self-reported abnormal skin sensitivity has a high sensitivity to identify patients with DMA, but its low specificity indicates that many patients mean something other than DMA when reporting this symptom. Self-reported deep pain is related to deep-tissue hypersensitivity, but thermal qualities of ongoing pain are not related to thermal hyperalgesia. Questionnaires mostly evaluate the ongoing pain experience, whereas QST mirrors sensory functions. Therefore, both methods are complementary for pain assessment.

Translational strategies in drug development for knee osteoarthritis

Osteoarthritis (OA) is a common disease worldwide with large unmet medical needs. To bring innovative treatments to OA patients, we at Merck have implemented a comprehensive strategy for drug candidate evaluation. We have a clear framework for decision-making in our preclinical pipeline, to design our clinical proof-of-concept trials for OA patients. We have qualified our strategy to define and refine dose and dosing regimen, for treatments administered either systemically or intra-articularly (IA). We do this through preclinical in vitro and in vivo studies, and by back-translating results from clinical studies in OA patients.

The Effect of Neuropathic Pain Symptoms on Remission in Patients with Early Rheumatoid Arthritis

BACKGROUND

The presence of neuropatic pain (NeP) is common in subjects with established Rheumatoid Arthritis (RA), and it can influence the disease remission. These aspects have not been investigated in patients with Early Rheumatoid Arthritis (ERA).

OBJECTIVE

To investigate the effect of NeP on the achievement of remission in patients with ERA.

METHOD

The study involved consecutive ERA patients with moderate or high disease activity. The painDETECT Questionnaire (PDQ), the 36-item Short Form Health Survey (SF-36), and the Euro- QoL-5 Dimensions (EQ-5D) were administered to all the patients, and their co-morbidity data were used to calculate their modified Rheumatic Disease Comorbidity Index (mRDCI). After six months' follow-up, the presence or otherwise of NeP in each individual patient was calculated, and whether or not the Boolean remission criteria were satisfied.

RESULTS

The study was completed by 115 patients (76% females) whose PDQ scores indicated that 13% had probable NeP. At the end of the follow-up period, 25 patients (21.7%) met the Boolean remission criteria. Logistic regression analysis showed that baseline PDQ scores (p=0.0023) and the mRDCI (p=0.0054) were the strongest predictors of not being in Boolean remission. Only one of the 15 patients with concomitant NeP achieved Boolean remission.

CONCLUSION

The presence of NeP may affect the achievement of remission in ERA patients. The PDQ can be a useful tool to measure central pain sensitisation in such patients.

The impact of anxiety on chronic musculoskeletal pain and the role of astrocyte activation

Supplemental Digital Content is Available in the Text.

Anxiety predicts onset of knee pain and drives greater osteoarthritis pain in humans. Our validated preclinical model identifies supraspinal astrocytosis as a potential mechanism.

Anxiety and depression are associated with increased pain responses in chronic pain states. The extent to which anxiety drives chronic pain, or vice versa, remains an important question that has implications for analgesic treatment strategies. Here, the effect of existing anxiety on future osteoarthritis (OA) pain was investigated, and potential mechanisms were studied in an animal model. Pressure pain detection thresholds, anxiety, and depression were assessed in people with (n = 130) or without (n = 100) painful knee OA. Separately, knee pain and anxiety scores were also measured twice over 12 months in 4730 individuals recruited from the general population. A preclinical investigation of a model of OA pain in normo-anxiety Sprague-Dawley (SD) and high-anxiety Wistar Kyoto (WKY) rats assessed underlying neurobiological mechanisms. Higher anxiety, independently from depression, was associated with significantly lower pressure pain detection thresholds at sites local to (P < 0.01) and distant from (P < 0.05) the painful knee in patients with OA. Separately, high anxiety scores predicted increased risk of knee pain onset in 3274 originally pain-free people over the 1-year period (odds ratio = 1.71; 95% confidence interval = 1.25-2.34, P < 0.00083). Similarly, WKY rats developed significantly lower ipsilateral and contralateral hind paw withdrawal thresholds in the monosodium iodoacetate model of OA pain, compared with SD rats (P = 0.0005). Linear regressions revealed that baseline anxiety-like behaviour was predictive of lowered paw withdrawal thresholds in WKY rats, mirroring the human data. This augmented pain phenotype was significantly associated with increased glial fibrillary acidic protein immunofluorescence in pain-associated brain regions, identifying supraspinal astrocyte activation as a significant mechanism underlying anxiety-augmented pain behaviour.

Central Sensitization in Knee Osteoarthritis: Relating Presurgical Brainstem Neuroimaging and PainDETECT-Based Patient Stratification to Arthroplasty Outcome

OBJECTIVE

The neural mechanisms of pain in knee osteoarthritis (OA) are not fully understood, and some patients have neuropathic-like pain associated with central sensitization. To address this, we undertook the present study in order to identify central sensitization using neuroimaging and PainDETECT and to relate it to postarthroplasty outcome.

METHODS

Patients awaiting arthroplasty underwent quantitative sensory testing, psychological assessment, and functional magnetic resonance imaging (fMRI). Neuroimaging (fMRI) was conducted during punctate stimulation (n = 24) and cold stimulation (n = 20) to the affected knee. The postoperative outcome was measured using the Oxford Knee Score, patient-reported moderate-to-severe long-term pain postarthroplasty, and a range of pain-related questionnaires.

RESULTS

Patients with neuropathic-like pain presurgery (identified using PainDETECT; n = 14) reported significantly higher pain in response to punctate stimuli and cold stimuli near the affected joint (P < 0.05). Neural activity in these patients, compared to those without neuropathic-like pain, was significantly lower in the rostral anterior cingulate cortex (P < 0.05) and higher in the rostral ventromedial medulla (RVM) during punctate stimulation (P < 0.05), with significant functional connectivity between these two areas (r = 0.49, P = 0.018). Preoperative neuropathic-like pain and higher neural activity in the RVM were associated with moderate-to-severe long-term pain after arthroplasty (P = 0.0356).

CONCLUSION

The psychophysical and neuroimaging data suggest that a subset of OA patients have centrally mediated pain sensitization. This was likely due to supraspinally mediated reductions in inhibition and increases in facilitation of nociceptive signaling, and was associated with a worse outcome following arthroplasty. The neurobiologic confirmation of central sensitization in patients with features of neuropathic pain, identified using PainDETECT, provides further support for the investigation of such bedside measures for patient stratification, to better predict postsurgical outcomes.

Pregabalin for neuropathic pain in adults

BACKGROUND

This review updates part of an earlier Cochrane Review titled "Pregabalin for acute and chronic pain in adults", and considers only neuropathic pain (pain from damage to nervous tissue). Antiepileptic drugs have long been used in pain management. Pregabalin is an antiepileptic drug used in management of chronic pain conditions.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of pregabalin for chronic neuropathic pain in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase for randomised controlled trials from January 2009 to April 2018, online clinical trials registries, and reference lists.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing pregabalin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and biases. Primary outcomes were: at least 30% pain intensity reduction over baseline; much or very much improved on the Patient Global Impression of Change (PGIC) Scale (moderate benefit); at least 50% pain intensity reduction; or very much improved on PGIC (substantial benefit). We calculated risk ratio (RR) and number needed to treat for an additional beneficial (NNTB) or harmful outcome (NNTH). We assessed the quality of the evidence using GRADE.

MAIN RESULTS

We included 45 studies lasting 2 to 16 weeks, with 11,906 participants - 68% from 31 new studies. Oral pregabalin doses of 150 mg, 300 mg, and 600 mg daily were compared with placebo. Postherpetic neuralgia, painful diabetic neuropathy, and mixed neuropathic pain predominated (85% of participants). High risk of bias was due mainly to small study size (nine studies), but many studies had unclear risk of bias, mainly due to incomplete outcome data, size, and allocation concealment.Postherpetic neuralgia: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (50% vs 25%; RR 2.1 (95% confidence interval (CI) 1.6 to 2.6); NNTB 3.9 (3.0 to 5.6); 3 studies, 589 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (32% vs 13%; RR 2.5 (95% CI 1.9 to 3.4); NNTB 5.3 (3.9 to 8.1); 4 studies, 713 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (62% vs 24%; RR 2.5 (95% CI 2.0 to 3.2); NNTB 2.7 (2.2 to 3.7); 3 studies, 537 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (41% vs 15%; RR 2.7 (95% CI 2.0 to 3.5); NNTB 3.9 (3.1 to 5.5); 4 studies, 732 participants, moderate-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 16% versus 5.5%, 600 mg 25% versus 5.8%; dizziness 300 mg 29% versus 8.1%, 600 mg 35% versus 8.8%.Painful diabetic neuropathy: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (47% vs 42%; RR 1.1 (95% CI 1.01 to 1.2); NNTB 22 (12 to 200); 8 studies, 2320 participants, moderate-quality evidence), more had at least 50% pain intensity reduction (31% vs 24%; RR 1.3 (95% CI 1.2 to 1.5); NNTB 22 (12 to 200); 11 studies, 2931 participants, moderate-quality evidence), and more had PGIC much or very much improved (51% vs 30%; RR 1.8 (95% CI 1.5 to 2.0); NNTB 4.9 (3.8 to 6.9); 5 studies, 1050 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (63% vs 52%; RR 1.2 (95% CI 1.04 to 1.4); NNTB 9.6 (5.5 to 41); 2 studies, 611 participants, low-quality evidence), and more had at least 50% pain intensity reduction (41% vs 28%; RR 1.4 (95% CI 1.2 to 1.7); NNTB 7.8 (5.4 to 14); 5 studies, 1015 participants, low-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 11% versus 3.1%, 600 mg 15% versus 4.5%; dizziness 300 mg 13% versus 3.8%, 600 mg 22% versus 4.4%.Mixed or unclassified post-traumatic neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (48% vs 36%; RR 1.2 (1.1 to 1.4); NNTB 8.2 (5.7 to 15); 4 studies, 1367 participants, low-quality evidence), and more had at least 50% pain intensity reduction (34% vs 20%; RR 1.5 (1.2 to 1.9); NNTB 7.2 (5.4 to 11); 4 studies, 1367 participants, moderate-quality evidence). Somnolence (12% vs 3.9%) and dizziness (23% vs 6.2%) were more common with pregabalin.Central neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (44% vs 28%; RR 1.6 (1.3 to 2.0); NNTB 5.9 (4.1 to 11); 3 studies, 562 participants, low-quality evidence) and at least 50% pain intensity reduction (26% vs 15%; RR 1.7 (1.2 to 2.3); NNTB 9.8 (6.0 to 28); 3 studies, 562 participants, low-quality evidence). Somnolence (32% vs 11%) and dizziness (23% vs 8.6%) were more common with pregabalin.Other neuropathic pain conditions: Studies show no evidence of benefit for 600 mg pregabalin in HIV neuropathy (2 studies, 674 participants, moderate-quality evidence) and limited evidence of benefit in neuropathic back pain or sciatica, neuropathic cancer pain, or polyneuropathy.Serious adverse events, all conditions: Serious adverse events were no more common with placebo than with pregabalin 300 mg (3.1% vs 2.6%; RR 1.2 (95% CI 0.8 to 1.7); 17 studies, 4112 participants, high-quality evidence) or pregabalin 600 mg (3.4% vs 3.4%; RR 1.1 (95% CI 0.8 to 1.5); 16 studies, 3995 participants, high-quality evidence).

AUTHORS' CONCLUSIONS

Evidence shows efficacy of pregabalin in postherpetic neuralgia, painful diabetic neuralgia, and mixed or unclassified post-traumatic neuropathic pain, and absence of efficacy in HIV neuropathy; evidence of efficacy in central neuropathic pain is inadequate. Some people will derive substantial benefit with pregabalin; more will have moderate benefit, but many will have no benefit or will discontinue treatment. There were no substantial changes since the 2009 review.

Mechanisms of Osteoarthritic Pain. Studies in Humans and Experimental Models

Pain due to osteoarthritis (OA) is one of the most frequent causes of chronic pain. However, the mechanisms of OA pain are poorly understood. This review addresses the mechanisms which are thought to be involved in OA pain, derived from studies on pain mechanisms in humans and in experimental models of OA. Three areas will be considered, namely local processes in the joint associated with OA pain, neuronal mechanisms involved in OA pain, and general factors which influence OA pain. Except the cartilage all structures of the joints are innervated by nociceptors. Although the hallmark of OA is the degradation of the cartilage, OA joints show multiple structural alterations of cartilage, bone and synovial tissue. In particular synovitis and bone marrow lesions have been proposed to determine OA pain whereas the contribution of the other pathologies to pain generation has been studied less. Concerning the peripheral neuronal mechanisms of OA pain, peripheral nociceptive sensitization was shown, and neuropathic mechanisms may be involved at some stages. Structural changes of joint innervation such as local loss and/or sprouting of nerve fibers were shown. In addition, central sensitization, reduction of descending inhibition, descending excitation and cortical atrophies were observed in OA. The combination of different neuronal mechanisms may define the particular pain phenotype in an OA patient. Among mediators involved in OA pain, nerve growth factor (NGF) is in the focus because antibodies against NGF significantly reduce OA pain. Several studies show that neutralization of interleukin-1β and TNF may reduce OA pain. Many patients with OA exhibit comorbidities such as obesity, low grade systemic inflammation and diabetes mellitus. These comorbidities can significantly influence the course of OA, and pain research just began to study the significance of such factors in pain generation. In addition, psychologic and socioeconomic factors may aggravate OA pain, and in some cases genetic factors influencing OA pain were found. Considering the local factors in the joint, the neuronal processes and the comorbidities, a better definition of OA pain phenotypes may become possible. Studies are under way in order to improve OA and OA pain monitoring.

Fourteen days of etoricoxib 60 mg improves pain, hyperalgesia and physical function in individuals with knee osteoarthritis: a randomized controlled trial

OBJECTIVE

Mounting evidence points to the heterogeneity of osteoarthritis (OA) pain, increasing the need for more comprehensive assessment of the efficacy of standard interventions. This study investigated whether 14 days of the selective Cox-2 inhibitor etoricoxib (60 mg/day) would modify self-report of pain intensity and quality, and physical measures of hyperalgesia and function in individuals with knee OA.

DESIGN

This double-blind placebo-controlled trial included 80 community-recruited volunteers with painful knee OA (≥3/10 VAS), randomly allocated to Active or Placebo groups. Self-report measures of pain, stiffness, function Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and pain quality (PainDETECT, Pain Quality Assessment Scale [PQAS]) and physical measures of locomotion and local (knee) and widespread (elbow) hyperalgesia were assessed at Days 0, 4 and 14. Repeated Measures ANOVA analysed group differences.

RESULTS

Significant group × time interaction effects were found for all measures of pain (all p < 0.001), with WOMAC pain sub-score improving by 30.7% by Day 14 and index knee mechanical hyperalgesia improving by 32.6%, whilst Placebo group values worsened. Both self-report and physical tests of function improved (p < 0.001-p = 0.006): WOMAC-function by 28.4%, sit-to-stand and walk time by 13%, pain during locomotion tasks by 12.4-32.6%. Pain quality also significantly improved for the Active and declined for the Placebo group (p < 0.001): PainDETECT score reduced by 23.6% and PQAS paroxsysmal and surface sub-scores by 36.9% and 29.4%. There were also significant improvements in local cold hyperalgesia and widespread mechanical hyperalgesia (10-13.8%).

CONCLUSION

Just 14 days of etoricoxib significantly improves pain intensity and quality, function and local and widespread hyperalgesia, measured by both self-report and physical tests.

The Influence of Arthritis in Other Major Joints and the Spine on the One-Year Outcome of Total Hip Replacement: A Prospective, Multicenter Cohort Study (EUROHIP) Measuring the Influence of Musculoskeletal Morbidity

BACKGROUND

Although arthritis in other affected major joints and back pain are known to lead to worse outcomes following total hip replacement, to our knowledge, these risk factors have not previously been operationalized as a musculoskeletal morbidity profile. The aim of this study was to measure the influence of other major joints and the spine (as grades of musculoskeletal morbidity) on the 1-year outcome of primary total hip replacement.

METHODS

The EUROHIP study consists of 1,327 patients undergoing primary total hip replacement for arthritis across 20 European orthopaedic centers. The primary outcome was the responder rate at 12 months calculated with the relative effect per patient for total hip replacement using the total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The primary predictor of interest was different combinations of arthritis of major joints and the spine grouped into 4 musculoskeletal morbidity grades: 1 (single major joint), 2 (multiple major joints), 3 (single major joint and spine), and 4 (multiple major joints and spine). The confounders adjusted for were age, sex, body mass index, living situation, years of hip pain, American Society of Anesthesiologists (ASA) class, anxiety or depression, and preoperative WOMAC subscales.

RESULTS

For this analysis, 845 patients were included with complete 12-month follow-up WOMAC scores. The mean patient age was 65.7 years, and 55.2% of patients were female.

CONCLUSIONS

The involvement of other major joints and the spine assessed as 1 of 4 musculoskeletal morbidity grades had a strong influence on the 1-year outcome after total hip replacement. The effect size was large compared with other risk factors. Even so, the majority of patients in musculoskeletal morbidity grade 4 had favorable outcomes from the surgical procedure (>74% response to surgical procedures).

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Gabapentin for chronic neuropathic pain in adults

BACKGROUND

Gabapentin is commonly used to treat neuropathic pain (pain due to nerve damage). This review updates a review published in 2014, and previous reviews published in 2011, 2005 and 2000.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain in adults.

SEARCH METHODS

For this update we searched CENTRAL), MEDLINE, and Embase for randomised controlled trials from January 2014 to January 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trials registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing gabapentin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). We performed a pooled analysis for any substantial or moderate benefit. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We included four new studies (530 participants), and excluded three previously included studies (126 participants). In all, 37 studies provided information on 5914 participants. Most studies used oral gabapentin or gabapentin encarbil at doses of 1200 mg or more daily in different neuropathic pain conditions, predominantly postherpetic neuralgia and painful diabetic neuropathy. Study duration was typically four to 12 weeks. Not all studies reported important outcomes of interest. High risk of bias occurred mainly due to small size (especially in cross-over studies), and handling of data after study withdrawal.In postherpetic neuralgia, more participants (32%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (17%) (RR 1.8 (95% CI 1.5 to 2.1); NNT 6.7 (5.4 to 8.7); 8 studies, 2260 participants, moderate-quality evidence). More participants (46%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (25%) (RR 1.8 (95% CI 1.6 to 2.0); NNT 4.8 (4.1 to 6.0); 8 studies, 2260 participants, moderate-quality evidence).In painful diabetic neuropathy, more participants (38%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (21%) (RR 1.9 (95% CI 1.5 to 2.3); NNT 5.9 (4.6 to 8.3); 6 studies, 1277 participants, moderate-quality evidence). More participants (52%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (37%) (RR 1.4 (95% CI 1.3 to 1.6); NNT 6.6 (4.9 to 9.9); 7 studies, 1439 participants, moderate-quality evidence).For all conditions combined, adverse event withdrawals were more common with gabapentin (11%) than with placebo (8.2%) (RR 1.4 (95% CI 1.1 to 1.7); NNH 30 (20 to 65); 22 studies, 4346 participants, high-quality evidence). Serious adverse events were no more common with gabapentin (3.2%) than with placebo (2.8%) (RR 1.2 (95% CI 0.8 to 1.7); 19 studies, 3948 participants, moderate-quality evidence); there were eight deaths (very low-quality evidence). Participants experiencing at least one adverse event were more common with gabapentin (63%) than with placebo (49%) (RR 1.3 (95% CI 1.2 to 1.4); NNH 7.5 (6.1 to 9.6); 18 studies, 4279 participants, moderate-quality evidence). Individual adverse events occurred significantly more often with gabapentin. Participants taking gabapentin experienced dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (14%).

AUTHORS' CONCLUSIONS

Gabapentin at doses of 1800 mg to 3600 mg daily (1200 mg to 3600 mg gabapentin encarbil) can provide good levels of pain relief to some people with postherpetic neuralgia and peripheral diabetic neuropathy. Evidence for other types of neuropathic pain is very limited. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. Around 3 or 4 out of 10 participants achieved this degree of pain relief with gabapentin, compared with 1 or 2 out of 10 for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief but may experience adverse events. Conclusions have not changed since the previous update of this review.

Morphine for chronic neuropathic pain in adults

BACKGROUND

Neuropathic pain, which is caused by a lesion or disease affecting the somatosensory system, may be central or peripheral in origin. Neuropathic pain often includes symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the nervous system. Opioid drugs, including morphine, are commonly used to treat neuropathic pain. Most reviews have examined all opioids together. This review sought evidence specifically for morphine; other opioids are considered in separate reviews.

OBJECTIVES

To assess the analgesic efficacy and adverse events of morphine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase for randomised controlled trials from inception to February 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing morphine (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We identified five randomised, double-blind, cross-over studies with treatment periods of four to seven weeks, involving 236 participants in suitably characterised neuropathic pain; 152 (64%) participants completed all treatment periods. Oral morphine was titrated to maximum daily doses of 90 mg to 180 mg or the maximum tolerated dose, and then maintained for the remainder of the study. Participants had experienced moderate or severe neuropathic pain for at least three months. Included studies involved people with painful diabetic neuropathy, chemotherapy-induced peripheral neuropathy, postherpetic neuralgia criteria, phantom limb or postamputation pain, and lumbar radiculopathy. Exclusions were typically people with other significant comorbidity or pain from other causes.Overall, we judged the studies to be at low risk of bias, but there were concerns over small study size and the imputation method used for participants who withdrew from the studies, both of which could lead to overestimation of treatment benefits and underestimation of harm.There was insufficient or no evidence for the primary outcomes of interest for efficacy or harm. Four studies reported an approximation of moderate pain improvement (any pain-related outcome indicating some improvement) comparing morphine with placebo in different types of neuropathic pain. We pooled these data in an exploratory analysis. Moderate improvement was experienced by 63% (87/138) of participants with morphine and 36% (45/125) with placebo; the risk difference (RD) was 0.27 (95% confidence interval (CI) 0.16 to 0.38, fixed-effects analysis) and the NNT 3.7 (2.6 to 6.5). We assessed the quality of the evidence as very low because of the small number of events; available information did not provide a reliable indication of the likely effect, and the likelihood that the effect will be substantially different was very high. A similar exploratory analysis for substantial pain relief on three studies (177 participants) showed no difference between morphine and placebo.All-cause withdrawals in four studies occurred in 16% (24/152) of participants with morphine and 12% (16/137) with placebo. The RD was 0.04 (-0.04 to 0.12, random-effects analysis). Adverse events were inconsistently reported, more common with morphine than with placebo, and typical of opioids. There were two serious adverse events, one with morphine, and one with a combination of morphine and nortriptyline. No deaths were reported. These outcomes were assessed as very low quality because of the limited number of participants and events.

AUTHORS' CONCLUSIONS

There was insufficient evidence to support or refute the suggestion that morphine has any efficacy in any neuropathic pain condition.

Fentanyl for neuropathic pain in adults

BACKGROUND

Opioid drugs, including fentanyl, are commonly used to treat neuropathic pain, and are considered effective by some professionals. Most reviews have examined all opioids together. This review sought evidence specifically for fentanyl, at any dose, and by any route of administration. Other opioids are considered in separate reviews.

OBJECTIVES

To assess the analgesic efficacy of fentanyl for chronic neuropathic pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to June 2016, together with the reference lists of retrieved articles, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing fentanyl (in any dose, administered by any route, and in any formulation) with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

Only one study met our inclusion criteria. Participants were men and women (mean age 67 years), with postherpetic neuralgia, complex regional pain syndrome, or chronic postoperative pain. They were experiencing inadequate relief from non-opioid analgesics, and had not previously taken opioids for their neuropathic pain. The study used an enriched enrolment randomised withdrawal design. It was adequately blinded, but we judged it at unclear risk of bias for other criteria.Transdermal fentanyl (one-day fentanyl patch) was titrated over 10 to 29 days to establish the maximum tolerated and effective dose (12.5 to 50 µg/h). Participants who achieved a prespecified good level of pain relief with a stable dose of fentanyl, without excessive use of rescue medication or intolerable adverse events ('responders'), were randomised to continue with fentanyl or switch to placebo for 12 weeks, under double-blind conditions. Our prespecified primary outcomes were not appropriate for this study design, but the measures reported do give an indication of the efficacy of fentanyl in this condition.In the titration phase, 1 in 3 participants withdrew because of adverse events or inadequate pain relief, and almost 90% experienced adverse events. Of 258 participants who underwent open-label titration, 163 were 'responders' and entered the randomised withdrawal phase. The number of participants completing the study (and therefore continuing on treatment) without an increase of pain by more than 15/100 was 47/84 (56%) with fentanyl and 28/79 (35%) with placebo. Because only 63% responded sufficiently to enter the randomised withdrawal phase, this implies that only a maximum of 35% of participants entering the study would have had useful pain relief and tolerability with transdermal fentanyl, compared with 22% with placebo. Almost 60% of participants taking fentanyl were 'satisfied' and 'very satisfied' with their treatment at the end of the study, compared with about 40% with placebo. This outcome approximates to our primary outcome of moderate benefit using the Patient Global Impression of Change scale, but the group was enriched for responders and the method of analysis was not clear. The most common adverse events were constipation, nausea, somnolence, and dizziness.There was no information about other types of neuropathic pain, other routes of administration, or comparisons with other treatments.We downgraded the quality of the evidence to very low because there was only one study, with few participants and events, and there was no information about how data from people who withdrew were analysed.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the suggestion that fentanyl works in any neuropathic pain condition.

Association of neuropathic pain with ultrasonographic measurements of femoral cartilage thickness and clinical parameters in patients with knee osteoarthritis

[Purpose] The aim of this study was to investigate whether neuropathic pain is associated with femoral condylar cartilage thickness, electrical pain threshold, and clinical parameters in patients with knee osteoarthritis. [Subjects and Methods] Sixty patients over the age of 40 diagnosed with knee osteoarthritis were enrolled. The PainDETECT questionnaire, Western Ontario and McMaster Universities Osteoarthritis Index, Hospital Anxiety and Depression Scale, and Short Form-36 questionnaire were completed for all patients. Electrical sensory threshold and electrical pain threshold measurements were obtained. Femoral condylar cartilage thickness was determined by means of ultrasound. [Results] PainDETECT scores of 13 or greater were observed in 28 (46.7%) patients, indicating the presence of neuropathic pain. These patients were found to have greater average pain severity, Western Ontario and McMaster Universities Osteoarthritis Index, and depression and anxiety scores and lower Short Form-36 scores than patients without neuropathic pain. Patients with neuropathic pain showed lower knee electrical sensory threshold and pain threshold values on average than patients without neuropathic pain. Femoral condylar cartilage thickness was not different between the two groups. [Conclusion] Neuropathic pain is associated with increased pain severity and decreased functional capacity and adversely affects quality of life and mood in patients with knee osteoarthritis.

The painDETECT project - far more than a screening tool on neuropathic pain

Background and objectives The painDETECT questionnaire (PD-Q), a simple and reliable screening questionnaire of neuropathic pain, was developed in 2004 in cooperation with the German Research Network on Neuropathic Pain. The initial aim was to implement quality management and to improve the situation of neuropathic pain (NeP) patients in Germany. The PD-Q proved immediately successful and was translated into and validated in multiple languages. Subsequently a comprehensive electronic system (PD) comprising various validated questionnaires with regard to pain typical comorbidities, such as function, sleep, mood or anxiety, was implemented Germany wide. We aimed to provide a comprehensive overview about the development and validation as well as the application of the PD-Q in various clinical conditions. Methods This overview is based on a literature search on English full-text papers using the term 'painDETECT' in Medline and PubMed covering the time period from 2006 to September 2015, amended with further publications cited in the retrieved publications or provided by the questionnaire developers. Results PD-Q as screening tool for NeP described in patients with lower back pain (8 studies), rheumatoid arthritis and osteoarthritis (10), thoracotomy (2 studies), tumor diseases (4 studies), fibromyalgia (4 studies), diverse musculoskeletal conditions (12 studies) and diverse other conditions (10 studies). In addition, the PD-Q was used in 9 studies that investigated the effect of drugs for the treatment of patients with a NeP component. Conclusion To date more than 300,000 patients were assessed, providing the basis for one of the world's largest datasets for chronic pain. Among others the extensive pool of PD-Q data triggered the idea of subgrouping patients on the basis of their individual sensory profiles which might in the future lead to a stratified treatment approach and ultimately to personalized therapy. Started as a healthcare utilization project in Germany, the PD-Q is nowadays used for clinical and research purposes around the world.

Strategies for the prevention of knee osteoarthritis

Osteoarthritis (OA) has been thought of as a disease of cartilage that can be effectively treated surgically at severe stages with joint arthroplasty. Today, OA is considered a whole-organ disease that is amenable to prevention and treatment at early stages. OA develops slowly over 10-15 years, interfering with activities of daily living and the ability to work. Many patients tolerate pain, and many health-care providers accept pain and disability as inevitable corollaries of OA and ageing. Too often, health-care providers passively await final 'joint death', necessitating knee and hip replacements. Instead, OA should be viewed as a chronic condition, where prevention and early comprehensive-care models are the accepted norm, as is the case with other chronic diseases. Joint injury, obesity and impaired muscle function are modifiable risk factors amenable to primary and secondary prevention strategies. The strategies that are most appropriate for each patient should be identified, by selecting interventions to correct--or at least attenuate--OA risk factors. We must also choose the interventions that are most likely to be acceptable to patients, to maximize adherence to--and persistence with--the regimes. Now is the time to begin the era of personalized prevention for knee OA.

Neuropathic-like pain features and cross-sectional associations in rheumatoid arthritis

INTRODUCTION

Increasing evidence indicates that features suggestive of neuropathic pain may also be present in patients with common rheumatic conditions. The objective of this study was to examine neuropathic-like pain symptoms and associated factors in patients with rheumatoid arthritis.

METHODS

We used the painDETECT screening tool to identify possible or likely neuropathic pain in 159 outpatients with rheumatoid arthritis. Patients additionally completed other self-reported measures, while clinical measures were assessed to calculate the 28-joint Disease Activity Score. Univariate analyses and multivariable logistic regression were used to identify factors associated with neuropathic pain features.

RESULTS

According to the painDETECT, 27 patients (17.0 %) were classified as having likely neuropathic pain and 34 patients (21.4 %) as having possible neuropathic pain. Besides reporting more severe pain, patients with likely or possible neuropathic pain were more likely to meet the diagnostic criteria for fibromyalgia, to use analgesics, and to have more tender joints and a worse physical and mental health status as measured by the 36-item Short-Form health survey. In multivariable analysis, physical (P < 0.001) and mental health status (P = 0.006) remained significantly associated with neuropathic pain features, even after controlling for pain severity.

CONCLUSIONS

These findings suggest that a sizeable proportion of patients with relatively well-controlled rheumatoid arthritis report symptoms suggestive of neuropathic pain. Neuropathic-like pain symptoms are independently associated with worse self-reported physical and mental health.

Topical clonidine for neuropathic pain

BACKGROUND

Clonidine is a presynaptic alpha-2-adrenergic receptor agonist used for many years to treat hypertension and other conditions, including chronic pain. Adverse events associated with systemic use of the drug have limited its application. Topical use of drugs is currently gaining interest, as it may limit adverse events without loss of analgesic efficacy. Topical clonidine (TC) formulations have been investigated recently in clinical trials.

OBJECTIVES

The objectives of this review were to assess the analgesic efficacy of TC for chronic neuropathic pain in adults and to assess the frequency of adverse events associated with clinical use of TC for chronic neuropathic pain.

SEARCH METHODS

We searched the Cochrane Register of Studies (CRS) Online (Cochrane Central Register of Controlled Trials (CENTRAL)), MEDLINE and EMBASE databases, reference lists of retrieved papers and trial registries, and we contacted experts in the field. We performed the most recent search on 17 September 2014.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing TC versus placebo or other active treatment in patients with chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data from the studies and assessed bias. We planned three tiers of evidence analysis. The first tier was designed to analyse data meeting current best standards, by which studies reported the outcome of at least 50% pain intensity reduction over baseline (or its equivalent) without use of the last observation carried forward or other imputation method for dropouts, reported an intention-to-treat (ITT) analysis, lasted eight weeks or longer, had a parallel-group design and included at least 200 participants (preferably at least 400) in the comparison. The second tier was designed to use data from at least 200 participants but in cases in which one of the above conditions was not met. The third tier of evidence was assumed in other situations.

MAIN RESULTS

We included two studies in the review, with a total of 344 participants. Studies lasted 8 weeks and 12 weeks and compared TC versus placebo. 0.1%. TC was applied in gel form to the painful area two to three times daily.Studies included in this review were subject to potential bias and were classified as of moderate or low quality. One drug manufacturer supported both studies.We found no top-tier evidence for TC in neuropathic pain. Second-tier evidence indicated slight improvement after the drug was used in study participants with painful diabetic neuropathy (PDN). A greater number of participants in the TC group had at least 30% reduction in pain compared with placebo (risk ratio (RR) 1.35, 95% confidence interval (CI) 1.03 to 1.77; number needed to treat for an additional beneficial outcome (NNTB) 8.33, 95% CI 4.3 to 50). Third-tier evidence indicated that TC was no better than placebo for achieving at least 50% reduction in pain intensity and on the Patient Global Impression of Change Scale. The two included studies could be subject to significant bias. We found no studies that reported other neuropathic pain conditions.The rate of adverse events did not differ between groups, with the exception of a higher incidence of mild skin reactions in the placebo group, which should have no clinical significance.

AUTHORS' CONCLUSIONS

Limited evidence from a small number of studies of moderate to low quality suggests that TC may provide some benefit in peripheral diabetic neuropathy. The drug may be useful in situations for which no better treatment options are available because of lack of efficacy, contraindications or adverse events. Additional trials are needed to assess TC in other neuropathic pain conditions and to determine how patients who have a chance to respond to the drug should be selected for treatment.

Amitriptyline for neuropathic pain in adults

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 12, 2012. That review considered both fibromyalgia and neuropathic pain, but the effects of amitriptyline for fibromyalgia are now dealt with in a separate review.Amitriptyline is a tricyclic antidepressant that is widely used to treat chronic neuropathic pain (pain due to nerve damage). It is recommended as a first line treatment in many guidelines. Neuropathic pain can be treated with antidepressant drugs in doses below those at which the drugs act as antidepressants.

OBJECTIVES

To assess the analgesic efficacy of amitriptyline for relief of chronic neuropathic pain, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE to March 2015, together with two clinical trial registries, and the reference lists of retrieved papers, previous systematic reviews, and other reviews; we also used our own hand searched database for older studies.

SELECTION CRITERIA

We included randomised, double-blind studies of at least four weeks' duration comparing amitriptyline with placebo or another active treatment in chronic neuropathic pain conditions.

DATA COLLECTION AND ANALYSIS

We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks' duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

We included 15 studies from the earlier review and two new studies (17 studies, 1342 participants) in seven neuropathic pain conditions. Eight cross-over studies with 302 participants had a median of 36 participants, and nine parallel group studies with 1040 participants had a median of 84 participants. Study quality was modest, though most studies were at high risk of bias due to small size.There was no first-tier or second-tier evidence for amitriptyline in treating any neuropathic pain condition. Only third-tier evidence was available. For only two of seven studies reporting useful efficacy data was amitriptyline significantly better than placebo (very low quality evidence).More participants experienced at least one adverse event; 55% of participants taking amitriptyline and 36% taking placebo. The risk ratio (RR) was 1.5 (95% confidence interval (CI) 1.3 to 1.8) and the number needed to treat for an additional harmful outcome was 5.2 (3.6 to 9.1) (low quality evidence). Serious adverse events were rare. Adverse event and all-cause withdrawals were not different, but were rarely reported (very low quality evidence).

AUTHORS' CONCLUSIONS

Amitriptyline has been a first-line treatment for neuropathic pain for many years. The fact that there is no supportive unbiased evidence for a beneficial effect is disappointing, but has to be balanced against decades of successful treatment in many people with neuropathic pain. There is no good evidence of a lack of effect; rather our concern should be of overestimation of treatment effect. Amitriptyline should continue to be used as part of the treatment of neuropathic pain, but only a minority of people will achieve satisfactory pain relief. Limited information suggests that failure with one antidepressant does not mean failure with all.

Milnacipran for neuropathic pain in adults

BACKGROUND

Milnacipran is a serotonin-norepinephrine reuptake inhibitor (SNRI) that is sometimes used to treat chronic neuropathic pain and fibromyalgia. This is an update of an earlier review of milnacipran for neuropathic pain and fibromyalgia in adults originally published in The Cochrane Library Issue 3, 2012. We split that review so that this one looked only at neuropathic pain, and a separate review looks at fibromyalgia.

OBJECTIVES

To assess the analgesic efficacy and associated adverse events of milnacipran for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE to 23 February 2015, together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included randomised, double-blind studies of eight weeks' duration or longer, comparing milnacipran with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality. We did not carry out any analysis.

MAIN RESULTS

We included a single study of 40 participants with chronic low back pain with a neuropathic component. It found no difference in pain scores between milnacipran 100 mg to 200 mg daily or placebo after six weeks (very low quality evidence). Adverse event rates were similar between treatments, with too few data to draw conclusions (very low quality evidence).

AUTHORS' CONCLUSIONS

There was no evidence to support the use of milnacipran to treat neuropathic pain conditions.

Pain phenotype in patients with knee osteoarthritis: classification and measurement properties of painDETECT and self-report Leeds assessment of neuropathic symptoms and signs scale in a cross-sectional study

Objective

Multiple mechanisms are involved in pain associated with osteoarthritis (OA). The painDETECT and Self‐Report Leeds Assessment of Neuropathic Symptoms and Signs (S‐LANSS) questionnaires screen for neuropathic pain and may also identify individuals with musculoskeletal pain who exhibit abnormal central pain processing. The aim of this cross‐sectional study was to evaluate painDETECT and S‐LANSS for classification agreement and fit to the Rasch model, and to explore their relationship to pain severity and pain mechanisms in OA.

Methods

A total of 192 patients with knee OA completed questionnaires covering different aspects of pain. Another group of 77 patients with knee OA completed questionnaires and underwent quantitative sensory testing for pressure–pain thresholds (PPTs). Agreement between painDETECT and S‐LANSS was evaluated using kappa coefficients and receiver operator characteristic (ROC) curves. Rasch analysis of both questionnaires was conducted. Relationships between screening questionnaires and measures of pain severity or PPTs were calculated using correlations.

Results

PainDETECT and S‐LANSS shared a stronger correlation with each other than with measures of pain severity. ROC curves identified optimal cutoff scores for painDETECT and S‐LANSS to maximize agreement, but the kappa coefficient was low (κ = 0.33–0.46). Rasch analysis supported the measurement properties of painDETECT but not those of S‐LANSS. Higher painDETECT scores were associated with widespread reductions in PPTs.

Conclusion

The data suggest that painDETECT assesses pain quality associated with augmented central pain processing in patients with OA. Although developed as a screening questionnaire, painDETECT may also function as a measure of characteristics that indicate augmented central pain processing. Agreement between painDETECT and S‐LANSS for pain classification was low, and it is currently unknown which tool may best predict treatment outcome.

Zonisamide for neuropathic pain in adults

BACKGROUND

Antiepileptic drugs have been used in pain management since the 1960s; some have shown efficacy in treating different neuropathic pain conditions. The efficacy of zonisamide for the relief of neuropathic pain has not previously been reviewed.

OBJECTIVES

To assess the analgesic efficacy and associated adverse events of zonisamide for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (via CRSO), MEDLINE, EMBASE, and two clinical trials databases (ClinicalTrials.gov. and the World Health Organisation Clinical Trials Registry Platform) to 1 August 2014, together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing zonisamide with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 and over. We included only full journal publication articles and clinical trial summaries.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We considered the evidence using three tiers. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design); second tier evidence derived from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison; and third tier evidence derived from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility, or both.We planned to calculate risk ratio (RR) and numbers needed to treat (NNT) and harm (NNH) for one additional event using standard methods expected by The Cochrane Collaboration.

MAIN RESULTS

We included a single study treating 25 participants (13 zonisamide, 12 placebo) with painful diabetic neuropathy over 12 weeks. No first or second tier evidence was available for any outcome. The small size of the study and potential major bias due to a high proportion of early study withdrawals with zonisamide precluded any conclusions being drawn. There were two serious adverse events (one death) in zonisamide-treated participants, which were apparently not related to treatment.

AUTHORS' CONCLUSIONS

The review found a lack of evidence suggesting that zonisamide provides pain relief in any neuropathic pain condition. Effective medicines with much greater supportive evidence are available.

A cross-sectional study of pain sensitivity, disease-activity assessment, mental health, and fibromyalgia status in rheumatoid arthritis

Introduction

Pain remains the most important problem for people with rheumatoid arthritis (RA). Active inflammatory disease contributes to pain, but pain due to non-inflammatory mechanisms can confound the assessment of disease activity. We hypothesize that augmented pain processing, fibromyalgic features, poorer mental health, and patient-reported 28-joint disease activity score (DAS28) components are associated in RA.

Methods

In total, 50 people with stable, long-standing RA recruited from a rheumatology outpatient clinic were assessed for pain-pressure thresholds (PPTs) at three separate sites (knee, tibia, and sternum), DAS28, fibromyalgia, and mental health status. Multivariable analysis was performed to assess the association between PPT and DAS28 components, DAS28-P (the proportion of DAS28 derived from the patient-reported components of visual analogue score and tender joint count), or fibromyalgia status.

Results

More-sensitive PPTs at sites over or distant from joints were each associated with greater reported pain, higher patient-reported DAS28 components, and poorer mental health. A high proportion of participants (48%) satisfied classification criteria for fibromyalgia, and fibromyalgia classification or characteristics were each associated with more sensitive PPTs, higher patient-reported DAS28 components, and poorer mental health.

Conclusions

Widespread sensitivity to pressure-induced pain, a high prevalence of fibromyalgic features, higher patient-reported DAS28 components, and poorer mental health are all linked in established RA. The increased sensitivity at nonjoint sites (sternum and anterior tibia), as well as over joints, indicates that central mechanisms may contribute to pain sensitivity in RA. The contribution of patient-reported components to high DAS28 should inform decisions on disease-modifying or pain-management approaches in the treatment of RA when inflammation may be well controlled.

Nortriptyline for neuropathic pain in adults

BACKGROUND

Antidepressants are widely used to treat chronic neuropathic pain (pain due to nerve damage), usually in doses below those at which they exert antidepressant effects. An earlier review that included all antidepressants for neuropathic pain is being replaced by new reviews of individual drugs examining individual neuropathic pain conditions.Nortriptyline is a tricyclic antidepressant that is occasionally used for treating neuropathic pain, and is recommended in European, UK, and USA guidelines.

OBJECTIVES

To assess the analgesic efficacy and associated adverse events of nortriptyline for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE from inception to 7 January 2015, and the reference lists of retrieved papers and other reviews. We also searched two clinical trials databases for ongoing or unpublished studies.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing nortriptyline with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 years and over. We included only full journal publication articles and clinical trial summaries.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We considered the evidence using three tiers. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks' duration, parallel design); second tier evidence from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison; and third tier evidence from data involving small numbers of participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both.We planned to calculate risk ratio (RR) and numbers needed to treat for an additional beneficial outcome (NNT) and harmful outcome (NNH) using standard methods expected by The Cochrane Collaboration.

MAIN RESULTS

We included six studies treating 310 participants (mean or median age 49 to 64 years) with various neuropathic pain conditions. Five studies used a cross-over design, and one used a parallel-group design; 272 participants were randomised to treatment with nortriptyline, 145 to placebo, 94 to gabapentin, 56 to gabapentin plus nortriptyline, 55 to morphine, 55 to morphine plus nortriptyline, 39 to chlorimipramine, and 33 to amitriptyline. Treatment periods lasted from three to eight weeks. All studies had one or more sources of potential major bias.No study provided first or second tier evidence for any outcome. Only one study reported our primary outcome of people with at least 50% reduction in pain. There was no indication that either nortriptyline or gabapentin was more effective in postherpetic neuralgia (very low quality evidence). Two studies reported the number of people with at least moderate pain relief, and one reported the number who were satisfied with their pain relief and had tolerable adverse effects. We considered these outcomes to be equivalent to our other primary outcome of Patient Global Impression of Change (PGIC) much or very much improved.We could not pool data, but third tier evidence in individual studies indicated similar efficacy to other active interventions (gabapentin, morphine, chlorimipramine, and amitriptyline), and to placebo in the conditions studied (very low quality evidence). Adverse event reporting was inconsistent and fragmented. More participants reported adverse events with nortriptyline than with placebo, similar numbers with nortriptyline and other antidepressants (amitriptyline and chlorimipramine) and gabapentin, and slightly more with morphine (very low quality evidence). No study reported any serious adverse events or deaths.

AUTHORS' CONCLUSIONS

We found little evidence to support the use of nortriptyline to treat the neuropathic pain conditions included in this review. There were no studies in the treatment of trigeminal neuralgia. The studies were methodologically flawed, largely due to small size, and potentially subject to major bias. The results of this review do not support the use of nortriptyline as a first line treatment. Effective medicines with much greater supportive evidence are available, such as duloxetine and pregabalin.

Desipramine for neuropathic pain in adults

BACKGROUND

Antidepressants are widely used to treat chronic neuropathic pain (pain due to nerve damage), usually in doses below those at which they exert antidepressant effects. An earlier review that included all antidepressants for neuropathic pain is being replaced by new reviews of individual drugs examining individual neuropathic pain conditions.Desipramine is a tricyclic antidepressant that is occasionally used for treating neuropathic pain.

OBJECTIVES

To assess the analgesic efficacy of desipramine for chronic neuropathic pain in adults, and to assess the associated adverse events.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE from inception to 29 April 2014, and the reference lists of retrieved papers and other reviews. We also used our own hand searched database to identify older studies, and two clinical trials databases for ongoing or unpublished studies.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks duration comparing desipramine with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 years and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence was derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts, at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design); second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison; and third tier from data involving small numbers of participants and considered very likely to be biased or that used outcomes of limited clinical utility, or both.

MAIN RESULTS

Five studies treated 177 participants with painful diabetic neuropathy (104) or postherpetic neuralgia (73). The mean or median ages in the studies were 55 to 72 years. Four studies used a cross-over, and one a parallel group design; 145 participants were randomised to receive desipramine 12.5 mg to 250 mg daily, with most taking 100 mg to 150 mg daily following titration. Comparators were placebo in three studies (an 'active placebo' in two studies), fluoxetine, clomipramine (one study each), and amitriptyline (two studies), and treatment was for two to six weeks. All studies had one or more sources of potential major bias.No study provided first or second tier evidence for any outcome. No data were available on the proportion of people with at least 50% or 30% reduction in pain, but data were available from three studies for our other primary outcome of Patient Global Impression of Change, reported as patient evaluation of pain relief that was 'complete' or 'a lot'. No pooling of data was possible, but third tier evidence in individual studies indicated some improvement in pain relief with desipramine compared with placebo, although this was very low quality evidence, derived mainly from group mean data and completer analyses in small, short duration studies where major bias was possible. There were too few participants in comparisons of desipramine with another active treatment to draw any conclusions.All studies reported some information about adverse events, but reporting was inconsistent and fragmented. Participants taking desipramine experienced more adverse events, and a higher rate of withdrawal due to adverse events, than did participants taking placebo (very low quality evidence).

AUTHORS' CONCLUSIONS

This review found little evidence to support the use of desipramine to treat neuropathic pain. There was very low quality evidence of benefit and harm, but this came from studies that were methodologically flawed and potentially subject to major bias. Effective medicines with much greater supportive evidence are available. There may be a role for desipramine in patients who have not obtained pain relief from other treatments.

The design and methods of genetic studies on acute and chronic postoperative pain in patients after total knee replacement

OBJECTIVE

Total knee replacement (TKR) is the treatment option of choice for the millions of individuals whose osteoarthritis pain can no longer be managed through non-invasive methods. Over 500,000 TKRs are performed annually in the United States. Although most patients report improvement in pain and functioning following TKR, up to 30% report persistent pain that interferes with daily function. However, the reasons for poor outcomes are not clear. To best determine which patients are at risk for pain post TKR, a detailed and comprehensive approach is needed. In this article, we present the methodology of a study designed to identify a set of genetic, proteomic, clinical, demographic, psychosocial, and psychophysical risk factors for severe acute and chronic pain post TKR.

DESIGN

Prospective longitudinal observational study.

SETTING

University Hospital System.

SUBJECTS

Patients scheduled for unilateral TKR with a target number of 150.

METHODS

Prior to surgery, we collect demographic, psychosocial, and pain data. Biological data, including blood samples for genetic analyses, and serum, urine, and joint fluid for cytokine assessment are collected intraoperatively. Pain assessments as well as medication use are collected during each of the three days postsurgery. Additionally, pain and psychosocial information is collected 6 and 12 months following surgery.

CONCLUSIONS

This study, for the first time, captures the information on both genetic and "environmental" risk factors for acute and chronic pain post-TKR and has the potential to lead to the next step-multicenter large-scale studies on predictors and biomarkers of poor TKR outcomes as well as on tailored interventions and personalized medicine approaches for those at risk.

A study protocol for the profile of pain in older women: assessing the multi dimensional nature of the experience of pain in arthritis

Background

Arthritis is a significant contributor to illness, pain and disability and imposes a considerable burden upon the community. Pain is a cardinal symptom of arthritis and has significant implications on biopsychosocial wellbeing. The multidimensional nature of the experience of pain in arthritis has not been well defined in community-based samples.

Aims

The two aims of this study are to generate profiles of pain from a community sample of older women and to compare profiles for women with and without arthritis.

Methods

The sub study is a cross-sectional postal survey of 700 Australian community-based women. The survey includes a range of measures on health, arthritis and pain that will be used to examine the multidimensional nature of the experience of pain in arthritis and generate profiles of pain.

Discussion

With no core set of measures for the evaluation of arthritis pain, this survey was created from an amalgamation of measures to capture multiple dimensions of pain. Findings from this study will assist in defining the symptom of pain in arthritis and may lead to further research in evidence-based treatment options for people with arthritis.

Topical lidocaine for neuropathic pain in adults

BACKGROUND

Lidocaine is a local anaesthetic that is sometimes used on the skin to treat neuropathic pain.

OBJECTIVES

To assess the analgesic efficacy of topical lidocaine for chronic neuropathic pain in adults, and to assess the associated adverse events.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE from inception to 1 July 2014, together with the reference lists of retrieved papers and other reviews. We also searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal to identify additional published or unpublished data.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing any formulation of topical lidocaine with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks' duration, parallel design); second tier evidence from data that failed to meet one or more of these criteria and that we considered at some risk of bias but with adequate numbers in the comparison; and third tier evidence from data involving small numbers of participants that we considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

We included 12 studies (508 participants) in comparisons with placebo or an active control. Six studies enrolled participants with moderate or severe postherpetic neuralgia, and the remaining studies enrolled different, or mixed, neuropathic pain conditions, including trigeminal neuralgia and postsurgical or post-traumatic neuralgia. Four different formulations were used: 5% medicated patch, 5% cream, 5% gel, and 8% spray. Most studies used a cross-over design, and two used a parallel-group design. Two studies used enriched enrolment with randomised withdrawal. Seven studies used multiple doses, with one to four-week treatment periods, and five used single applications. We judged all of the studies at high risk of bias because of small size or incomplete outcome assessment, or both.There was no first or second tier evidence, and no pooling of data was possible for efficacy outcomes. Only one multiple-dose study reported our primary outcome of participants with ≥ 50% or ≥ 30% pain intensity reduction. Three single-dose studies reported participants who were pain-free at a particular time point, or had a 2-point (of 10) reduction in pain intensity. The two enriched enrolment, randomised withdrawal studies reported time to loss of efficacy. In all but one study, third tier (very low quality) evidence indicated that lidocaine was better than placebo for some measure of pain relief. Pooling multiple-dose studies across conditions demonstrated no clear evidence of an effect of lidocaine on the incidence of adverse events or withdrawals, but there were few events and the withdrawal phase of enriched enrolment designs is not suitable to assess the true impact of adverse events (very low quality evidence).

AUTHORS' CONCLUSIONS

This review found no evidence from good quality randomised controlled studies to support the use of topical lidocaine to treat neuropathic pain, although individual studies indicated that it was effective for relief of pain. Clinical experience also supports efficacy in some patients. Several large ongoing studies, of adequate duration, with clinically useful outcomes should provide more robust conclusions about both efficacy and harm.

Levetiracetam for neuropathic pain in adults

BACKGROUND

Antiepileptic drugs have been used in pain management since the 1960s; some have shown efficacy in treating different neuropathic pain conditions. The efficacy of levetiracetam for relief of neuropathic pain has not previously been reviewed.

OBJECTIVES

To assess the analgesic efficacy and adverse events of levetiracetam in chronic neuropathic pain conditions in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 6) (via the Cochrane Library), MEDLINE, EMBASE, and two clinical trials databases (ClinicalTrials.gov. and the World Health Organisation Clinical Trials Registry Platform) to 3 July 2014, together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks duration or longer, comparing levetiracetam with placebo or another active treatment in adults with chronic neuropathic pain conditions. Studies had to have a minimum of 10 participants per treatments arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction; intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison; 8 to 12 weeks duration; parallel design); second tier evidence from data that failed to meet one or more of these criteria and that we considered at some risk of bias but with at least 200 participants in the comparison; and third tier evidence from data involving fewer than 200 participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

We included six studies: five small, cross-over studies with 174 participants, and one parallel group study with 170 participants. Participants were treated with levetiracetam (2000 mg to 3000 mg daily) or placebo for between four and 14 weeks. Each study included participants with a different type of neuropathic pain; central pain due to multiple sclerosis, pain following spinal cord injury, painful polyneuropathy, central post-stroke pain, postherpetic neuralgia, and post-mastectomy pain.None of the included studies provided first or second tier evidence. The evidence was very low quality, downgraded because of the small size of the treatment arms, and because studies reported results using last observation carried forward (LOCF) imputation for withdrawals or using only participants who completed the study according to the protocol, where there were greater than 10% withdrawals. There were insufficient data for a pooled efficacy analysis in particular neuropathic pain conditions, but individual studies did not show any analgesic effect of levetiracetam compared with placebo. We did pool results for any outcome considered substantial pain relief (≥ 50% pain intensity reduction or 'complete' or 'good' responses on the verbal rating scale) for four studies with dichotomous data; response rates across different types of neuropathic pain was similar with levetiracetam (10%) and placebo (12%), with no statistical difference (risk ratio 0.9; 95% confidence interval (CI) 0.4 to1.7).We pooled data across different conditions for adverse events and withdrawals. Based on very limited data, significantly more participants experienced an adverse event with levetiracetam than with placebo (number needed to treat for an additional harmful event (NNH) 8.0 (95% CI 4.6 to 32)). There were significantly more adverse event withdrawals with levetiracetam (NNH 9.7 (6.7 to 18)).

AUTHORS' CONCLUSIONS

The amount of evidence for levetiracetam in neuropathic pain conditions was very small and potentially biased because of the methods of analysis used in the studies. There was no indication that levetiracetam was effective in reducing neuropathic pain, but it was associated with an increase in participants who experienced adverse events and who withdrew due to adverse events.

Imipramine for neuropathic pain in adults

BACKGROUND

Antidepressants are widely used to treat chronic neuropathic pain (pain due to nerve damage), usually in doses below those at which they exert antidepressant effects. An earlier review that included all antidepressants for neuropathic pain is being replaced by new reviews of individual drugs examining individual neuropathic pain conditions.Imipramine is a tricyclic antidepressant that is occasionally used to treat neuropathic pain.

OBJECTIVES

To assess the analgesic efficacy of imipramine for chronic neuropathic pain in adults, and to assess the associated adverse events.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE on 18 November 2013, as well as the reference lists of retrieved papers and other reviews. We also used our own handsearched database for older studies, and two clinical trials databases.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing imipramine with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 and over. We included only articles with full journal publication and extended trial abstracts and summaries.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence was derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design); second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison; and third tier from data involving small numbers of participants which was considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

Five studies treated 168 participants with painful diabetic neuropathy or polyneuropathy. The mean age in individual studies was between 47 and 56 years. Four studies used a cross-over, and one a parallel group design; 126 participants were randomised to receive imipramine 25 mg to 350 mg daily (most took 100 mg to 150 mg daily). Comparators were placebo (an active placebo in one study), paroxetine, mianserin, venlafaxine, and amitriptyline, and treatment was given for 2 to 12 weeks. All studies had one or more sources of potential major bias.No study provided first or second tier evidence for any outcome. No data were available on the proportion of people with at least 50% or 30% reduction in pain or equivalent, and data were available from only one study for our other primary outcome of Patient Global Impression of Change, reported as patient evaluation of pain relief of complete or good. No pooling of data was possible, but third tier evidence in individual studies indicated some improvement in pain relief with imipramine compared with placebo, although this is was very low quality evidence, derived mainly from group mean data and completer analyses, in small, short duration studies where major bias is possible.Four studies reported some information about adverse events, but reporting was inconsistent and fragmented, and the quality of evidence was very low. Participants taking imipramine generally experienced more adverse events, notably dry mouth, and a higher rate of withdrawal due to adverse events, than did participants taking placebo.

AUTHORS' CONCLUSIONS

This review found little evidence to support the use of imipramine to treat neuropathic pain. There was very low quality evidence of benefit but this came from studies that were methodologically flawed and potentially subject to major bias. Effective medicines with much greater supportive evidence are available.

The role of screening tools in diagnosing neuropathic pain

SUMMARY: 

Neuropathic pain affects 6–8% of the general adult population. It is reported by 27% of chronic pain patients and 40% of cancer patients, yet there is no standardized diagnostic test for neuropathic pain. A number of screening tools have been developed based on verbal pain descriptors, with or without limited clinical examination, to identify individuals with neuropathic pain. Over the past decade these neuropathic pain screening tools have been validated in a wide range of pain populations, as well as translated into many languages, to discriminate between neuropathic and non-neuropathic pain. We describe here the five most commonly used neuropathic pain screening tools and discuss current assessment guidelines, the use of screening tools in novel clinical contexts and their potential use in personalized therapy.

Gabapentin for chronic neuropathic pain and fibromyalgia in adults

BACKGROUND

This review is an update of a review published in 2011, itself a major update of previous reviews published in 2005 and 2000, investigating the effects of gabapentin in chronic neuropathic pain (pain due to nerve damage). Antiepileptic drugs are used to manage chronic neuropathic pain and fibromyalgia.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain and fibromyalgia.

SEARCH METHODS

We identified randomised trials of gabapentin for chronic neuropathic pain or fibromyalgia by searching the databases MEDLINE (1966 to March 2014), EMBASE (1980 to 2014 week 10), and CENTRAL in The Cochrane Library (Issue 3 of 12, 2014). We obtained clinical trial reports and synopses of published and unpublished studies from Internet sources, and searched Clinicaltrials.gov. Searches were run originally in 2011 and the date of the most recent search was 17 March 2014.

SELECTION CRITERIA

Randomised, double-blind studies reporting the analgesic and adverse effects of gabapentin in neuropathic pain or fibromyalgia with assessment of pain intensity, pain relief, or both, using validated scales. Participants were adults.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted efficacy and adverse event data, examined issues of study quality, and assessed risk of bias. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility, or both.For efficacy, we calculated the number needed to treat to benefit (NNT), concentrating on at least 50% pain intensity reduction, and Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT) definitions of at least moderate and substantial benefit. For harm we calculated number needed to treat for harm (NNH) for adverse effects and withdrawal. Meta-analysis was undertaken using a fixed-effect model. We emphasised differences between conditions now defined as neuropathic pain, and other conditions like masticatory pain, complex regional painsyndrome type 1 (CRPS-1), and fibromyalgia.

MAIN RESULTS

Seven new studies with 1919 participants were added. Another report (147 participants) provided results for a study already included, but which previously had no usable data. A further report (170 participants) used an experimental formulation of intrathecal gabapentin. Thirty-seven studies (5633 participants) studied oral gabapentin at daily doses of 1200 mg or more in 12 chronic pain conditions; 84% of participants were in studies of postherpetic neuralgia, painful diabetic neuropathy or mixed neuropathic pain. There was no first tier evidence.Second tier evidence for the outcome of at least 50% pain intensity reduction, considered valuable by patients with chronic pain, showed that gabapentin was significantly better than placebo in postherpetic neuralgia (34% gabapentin versus 21% placebo; NNT 8.0, 95% CI 6.0 to 12) and painful diabetic neuropathy (38% versus 21%, NNT 5.9, 95% CI 4.6 to 8.3). There was insufficient information in other pain conditions to reach any reliable conclusion. There was no obvious difference between standard gabapentin formulations and recently-introduced extended-release or gastro-retentive formulations, or between different doses of gabapentin.Adverse events occurred significantly more often with gabapentin. Persons taking gabapentin could expect to have at least one adverse event (62%), withdraw because of an adverse event (11%), suffer dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (9%). Serious adverse events (3%) were no more common than with placebo.There were insufficient data for direct comparisons with other active treatments, and only third tier evidence for other painful conditions.

AUTHORS' CONCLUSIONS

There was no top tier evidence that was unequivocally unbiased. Second tier evidence, with potentially important residual biases, showed that gabapentin at doses of 1200 mg or more was effective for some people with some painful neuropathic pain conditions. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. About 35% achieved this degree of pain relief with gabapentin, compared with 21% for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief. Results might vary between different neuropathic pain conditions, and the amount of evidence for gabapentin in neuropathic pain conditions except postherpetic neuralgia and painful diabetic neuropathy, and in fibromyalgia, is very limited.The levels of efficacy found for gabapentin are consistent with those found for other drug therapies in postherpetic neuralgia and painful diabetic neuropathy.

Gabapentin for chronic neuropathic pain and fibromyalgia in adults

BACKGROUND

This review is an update of a review published in 2011, itself a major update of previous reviews published in 2005 and 2000, investigating the effects of gabapentin in chronic neuropathic pain (pain due to nerve damage). Antiepileptic drugs are used to manage chronic neuropathic pain and fibromyalgia.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain and fibromyalgia.

SEARCH METHODS

We identified randomised trials of gabapentin for chronic neuropathic pain or fibromyalgia by searching the databases MEDLINE (1966 to March 2014), EMBASE (1980 to 2014 week 10), and CENTRAL in The Cochrane Library (Issue 3 of 12, 2014). We obtained clinical trial reports and synopses of published and unpublished studies from Internet sources, and searched Clinicaltrials.gov. Searches were run originally in 2011 and the date of the most recent search was 17 March 2014.

SELECTION CRITERIA

Randomised, double-blind studies reporting the analgesic and adverse effects of gabapentin in neuropathic pain or fibromyalgia with assessment of pain intensity, pain relief, or both, using validated scales. Participants were adults.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted efficacy and adverse event data, examined issues of study quality, and assessed risk of bias. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility, or both.For efficacy, we calculated the number needed to treat to benefit (NNT), concentrating on at least 50% pain intensity reduction, and Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT) definitions of at least moderate and substantial benefit. For harm we calculated number needed to treat for harm (NNH) for adverse effects and withdrawal. Meta-analysis was undertaken using a fixed-effect model. We emphasised differences between conditions now defined as neuropathic pain, and other conditions like masticatory pain, complex regional painsyndrome type 1 (CRPS-1), and fibromyalgia.

MAIN RESULTS

Seven new studies with 1919 participants were added. Another report (147 participants) provided results for a study already included, but which previously had no usable data. A further report (170 participants) used an experimental formulation of intrathecal gabapentin. Thirty-seven studies (5633 participants) studied oral gabapentin at daily doses of 1200 mg or more in 12 chronic pain conditions; 84% of participants were in studies of postherpetic neuralgia, painful diabetic neuropathy or mixed neuropathic pain. There was no first tier evidence.Second tier evidence for the outcome of at least 50% pain intensity reduction, considered valuable by patients with chronic pain, showed that gabapentin was significantly better than placebo in postherpetic neuralgia (34% gabapentin versus 21% placebo; NNT 8.0, 95% CI 6.0 to 12) and painful diabetic neuropathy (38% versus 21%, NNT 5.9, 95% CI 4.6 to 8.3). There was insufficient information in other pain conditions to reach any reliable conclusion. There was no obvious difference between standard gabapentin formulations and recently-introduced extended-release or gastro-retentive formulations, or between different doses of gabapentin.Adverse events occurred significantly more often with gabapentin. Persons taking gabapentin could expect to have at least one adverse event (62%), withdraw because of an adverse event (11%), suffer dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (9%). Serious adverse events (3%) were no more common than with placebo.There were insufficient data for direct comparisons with other active treatments, and only third tier evidence for other painful conditions.

AUTHORS' CONCLUSIONS

There was no top tier evidence that was unequivocally unbiased. Second tier evidence, with potentially important residual biases, showed that gabapentin at doses of 1200 mg or more was effective for some people with some painful neuropathic pain conditions. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. About 35% achieved this degree of pain relief with gabapentin, compared with 21% for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief. Results might vary between different neuropathic pain conditions, and the amount of evidence for gabapentin in neuropathic pain conditions except postherpetic neuralgia and painful diabetic neuropathy, and in fibromyalgia, is very limited.The levels of efficacy found for gabapentin are consistent with those found for other drug therapies in postherpetic neuralgia and painful diabetic neuropathy.

Carbamazepine for chronic neuropathic pain and fibromyalgia in adults

BACKGROUND

This is an update of a Cochrane review entitled 'Carbamazepine for acute and chronic pain in adults' published in Issue 1, 2011. Some antiepileptic medicines have a place in the treatment of neuropathic pain (pain due to nerve damage). This updated review considers the treatment of chronic neuropathic pain and fibromyalgia only, and adds no new studies. The update uses higher standards of evidence than the earlier review, which results in the exclusion of five studies that were previously included.

OBJECTIVES

To assess the analgesic efficacy of carbamazepine in the treatment of chronic neuropathic pain and fibromyalgia, and to evaluate adverse events reported in the studies.

SEARCH METHODS

We searched for relevant studies in MEDLINE, EMBASE and CENTRAL up to February 2014. Additional studies were sought from clinical trials databases, and the reference list of retrieved articles and reviews.

SELECTION CRITERIA

Randomised, double blind, active or placebo controlled trials (RCTs) investigating the use of carbamazepine (any dose, by any route, and for at least two weeks' duration) for the treatment of chronic neuropathic pain or fibromyalgia, with at least 10 participants per treatment group. Participants were adults aged 18 and over.

DATA COLLECTION AND ANALYSIS

Two study authors independently extracted data on efficacy, adverse events, and withdrawals, and examined issues of study quality. Numbers needed to treat for an additional beneficial effect (NNT) or harmful effect (NNH) with 95% confidence intervals (CIs) were calculated from dichotomous data.We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts, at least 200 participants in the comparison, at least 8 weeks' duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

Ten included studies (11 publications) enrolled 480 participants with trigeminal neuralgia, diabetic neuropathy, and post stroke pain. Nine studies used a cross-over design, and one a parallel group design. Most of the studies were of short duration, lasting four weeks or less.No study provided first or second tier evidence for an efficacy outcome. Using third tier evidence, carbamazepine generally provided better pain relief than placebo in the three conditions studied, with some indication of pain improvement over mainly the short term, but with poorly defined outcomes, incomplete reporting, and in small numbers of participants. There were too few data in studies comparing carbamazepine with active comparators to draw any conclusions.In four studies 65% (113/173) of participants experienced at least one adverse event with carbamazepine, and 27% (47/173) with placebo; for every five participants treated, two experienced an adverse event who would not have done so with placebo. In eight studies 3% (8/268) of participants withdrew due to adverse events with carbamazepine, and none (0/255) with placebo. Serious adverse events were not reported consistently; rashes were associated with carbamazepine. Four deaths occurred in patients on carbamazepine, with no obvious drug association.

AUTHORS' CONCLUSIONS

Carbamazepine is probably effective in some people with chronic neuropathic pain, but with caveats. No trial was longer than four weeks, had good reporting quality, nor used outcomes equivalent to substantial clinical benefit. In these circumstances, caution is needed in interpretation, and meaningful comparison with other interventions is not possible.