Self-reported somatosensory symptoms of neuropathic pain in fibromyalgia and chronic widespread pain correlate with tender point count and pressure-pain thresholds

Can Clinical, Psychological, and Cognitive Patient-Reported Outcome Measures (PROMs) Help to Discriminate Women with Fibromyalgia from Those with Other Localized/Regional Pain Conditions? A Diagnostic Accuracy Study

Background and Objectives: The heterogeneous clinical manifestations of fibromyalgia syndrome have led to the revision of diagnostic criteria in the last decade. The aim of this study was to determine the capability of clinical, psychological, and cognitive patient-related outcome measures (PROMs) to differentiate women with fibromyalgia syndrome (FMS) from women with localized or regional pain conditions. Materials and Methods: A diagnostic accuracy study was conducted. Clinical (pain intensity-NPRS; related disability-FIQ), psychological (anxiety/depressive levels-HADS-A/HADS-D), and cognitive (sleep quality-PSQI; pain hypervigilance-PVAQ-9) PROMs were collected in 129 women with FMS and 65 women with localized/regional chronic pain conditions. The area under the receiver operating characteristic (ROC) curve, cut-off point, sensitivity/specificity values, and positive and negative likelihood (LR) ratios of each variable were calculated. Results: Women with FMS showed higher levels of pain, related disability, and anxiety/depressive levels, worse sleep quality, and higher levels of hypervigilance (all, p < 0.001) than women without FMS. All PROMs showed excellent discriminatory power and good sensitivity (pain intensity: ROC 0.987, sensitivity 91.5%; related disability: ROC 0.980, sensitivity 93.8%; HADS-A: ROC 0.901, sensitivity 81.4%; HADS-D: ROC 0.906, sensitivity 85.3%; PSQI: ROC 0.909, sensitivity 79.1%; PVAQ-9: ROC 0.798, sensitivity 80.6%). Specificity was extremely small for all variables (<18%) except for pain hypervigilance (specificity: 34%). Conclusions: Women with FMS exhibited worse clinical, psychological, and cognitive variables than women with localized/regional chronic pain. Although all PROMs had good discriminatory power, related disability and pain hypervigilance were those showing the best models. These PROMs could be combined with the American College of Rheumatology (ACR) diagnostic criteria to better discriminate between women with and without FMS. Studies investigating the relevance of combining these PROMs with the ACR diagnostic criteria in clinical settings are needed.

Chronic Widespread Pain

OBJECTIVE

This article reviews the potential etiologies of chronic widespread pain syndromes and outlines a practical approach to the management of patients with these disorders.

LATEST DEVELOPMENTS

Recent updates to diagnostic criteria for primary chronic widespread pain syndromes have allowed for more effective diagnosis. Fibromyalgia is the most common presentation of chronic widespread pain, and the concept of nociplastic pain has been used to describe pain that is related to altered processing of pain sensory pathways. Research studies have provided a better understanding of the pathophysiology of the central augmentation that occurs in patients with nociplastic pain and fibromyalgia.

ESSENTIAL POINTS

Primary chronic widespread pain and fibromyalgia have established diagnostic criteria in which chronic pain involves multiple defined regions and occurs for longer than 3 months. Evaluation of chronic widespread pain should be directed by the clinical presentation. Neurologic disease can present with chronic widespread pain but is accompanied by associated signs and symptoms. Patients with chronic widespread pain benefit from effective communication that validates concerns, provides an understandable explanation of the presenting symptoms, and sets realistic expectations in outcomes using a comprehensive multimodal care plan.

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.

Phenotypic characteristics of patients with chronic widespread pain and fibromyalgia: a cross-sectional cluster analysis

OBJECTIVE

This study aimed to explore whether phenotypic characteristics of patients with chronic widespread pain (CWP) and fibromyalgia (FM) can be aggregated into definable clusters that may help to tailor treatments.

METHOD

Baseline variables (sex, age, education, marital/employment status, pain duration, prior CWP/FM diagnosis, concomitant rheumatic disease, analgesics, tender point count, and disease variables derived from standardized questionnaires) collected from 1099 patients (93.4% females, mean age 44.6 years) with a confirmed CWP or FM diagnosis were evaluated by hierarchical cluster analysis. The number of clusters was based on coefficients in the agglomeration schedule, supported by dendrograms and silhouette plots. Simple and multiple regression analyses using all variables as independent predictors were used to assess the likelihood of cluster assignment, reported as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Only one cluster emerged (Cluster 1: 455 patients). Participants in this cluster were characterized as working (OR 66.67, 95% CI 7.14 to 500.00), with a medium-term/higher education (OR 16.80, 95% CI 1.94 to 145.41), married/cohabiting (OR 14.29, 95% CI 1.26 to 166.67), and using mild analgesics (OR 25.64, 95% CI 0.58 to > 999.99). The odds of being an individual in Cluster 1 were lower when having a worse score on the PDQ (score ≥ 18) (OR < 0.001, 95% CI < 0.001 to 0.02).

CONCLUSION

We identified one cluster, where participants were characterized by a potentially favourable clinical profile. More studies are needed to evaluate whether these characteristics could be used to guide the management of patients with CWP and FM.

Limited content overlap between commonly used self-report instruments for central (pain) sensitization in rheumatology

Objectives

Central pain mechanisms may be prominent in a considerable subset of rheumatology patients with persistent pain. Several self-report instruments have been used in previous research to infer the presence and severity of central sensitization (CS) that stem from different definitions or approaches of CS. The current study aimed to evaluate and quantify the overlap of actual symptoms measured among self-report measures of CS in rheumatology.

Methods

We used Fried's (2017) comprehensive systematic approach to analyse the content of five commonly used or typical self-report measures (Generalized Pain Questionnaire, Pain Sensitivity Questionnaire, Central Sensitization Inventory, Central Aspects of Pain in the Knee scale and the painDETECT) used in rheumatology research and to visualize and quantify the overlap in symptoms measured.

Results

The five instruments together measured 39 different symptoms, most of which could be grouped into nociplastic pain manifestations (7 symptoms), neuropathic pain qualities (5 symptoms), and psychosomatic symptoms and emotional distress (25 symptoms). Most symptoms (74.4%) were unique to a single instrument. Thermal allodynia was the most frequently measured symptom across the different instruments, assessed in four of the measures. Average content overlap was very low and ranged from no overlap at all to moderate overlap (Jaccard index = 0.43) between pairs of instruments.

Conclusion

There is high heterogeneity and limited overlap in the content of self-report measures used to infer central pain sensitization. This may lead to results that are specific to the particular instrument and may limit the generalizability and comparability of study findings in rheumatology research.

Role of Repetitive Transcranial Magnetic Stimulation in Treatment of Fibromyalgia: A Randomized Controlled Trial

Background and Objective

Fibromyalgia syndrome (FMS) is a chronic disease characterized by widespread, persistent musculoskeletal pain in association with impaired health-related quality of life. Repetitive transcranial magnetic stimulation (rTMS) is an emerging tool for the management of fibromyalgia. There is no standardized protocol of rTMS for the treatment of FMS, and both low- and high-frequency stimulation of the dorsolateral prefrontal cortex (DLPFC) are described in the literature with variable efficacy. The objective of this study was to determine the effectiveness of rTMS in people with fibromyalgia and compare the response of low- and high-frequency stimulation with sham stimulation.

Materials and Methods

This study was a single-blinded, randomized, placebo-controlled trial. Ninety patients with the diagnosis of FMS were randomly allocated into one of the following three groups: low-frequency (1 Hz) group, high-frequency (10 Hz) group, and sham group. Pain, depression, anxiety, and quality of life were measured using the Numerical Pain Rating Scale (NPRS), Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HDRS), and Revised Fibromyalgia Impact Questionnaire (FIQR) immediately following treatment as well as at 1 and 3 months after treatment. The data was statistically analyzed using Statistical Package for the Social Sciences version 23 software. P value < 0.05 was considered statistically significant.

Results

Intergroup analysis revealed a significant improvement in NPRS, HAM-A, HDRS, and FIQR scores in both low- and high- frequency groups immediately following treatment and for 3 months after treatment. No significant difference in the efficacy of low- and high-frequency stimulation was noticed.

Conclusions

rTMS is an effective mode of treatment in people with FMS. Both low and high frequencies of stimulation at DLPFC are equally effective in reducing pain and associated symptoms.

Quantitative sensory testing, psychological profiles and clinical pain in patients with psoriatic arthritis and hand osteoarthritis experiencing pain of at least moderate intensity

BACKGROUND

Chronic pain is the hallmark symptom of joint diseases. This study examined the differences in quantitative sensory testing between patients with psoriatic arthritis (PsA), hand osteoarthritis (hand-OA) and a pain-free control group and differences between patients with and without concomitant fibromyalgia (cFM).

METHODS

All patients and pain-free controls were assessed using pressure pain thresholds (PPT), temporal summation of pain (TSP), conditioned pain modulation (CPM) and clinical pain intensities. Psychological distress was assessed with the Hospital Anxiety and Depression Scale, Pain Catastrophizing Scale, and Pittsburgh Sleep Quality Index. Disability was assessed with the Health Assessment Questionnaire and pain quality with the painDETECT questionnaire. cFM was identified using the revised 2016 American College of Rheumatology diagnostic criteria.

RESULTS

Patients with hand-OA (n = 75) or PsA (n = 58) had statistically significant lower PPTs and CPM, greater TSP, and higher scores of psychological distress (p < 0.05) than controls (n = 20). Patients with cFM (58%) had higher scores of depression (p = 0.001), anxiety (p = 0.004), catastrophizing (p = 0.012), disability (p < 0.001), higher painDETECT score (p = 0.001), TSP (p = 0.027), and reduced sleep quality (p = 0.021) when compared to patients without cFM.

CONCLUSION

Patients with hand-OA and PsA exhibited signs of pain sensitization and a higher degree of psychological distress and disability than pain-free individuals. Patients with cFM had greater TSP, painDETECT score, disability, catastrophizing, and reduced sleep quality, than patients without, indicating greater degree of pain sensitization, psychological burden, and disability.

STATEMENT OF SIGNIFICANCE

This paper shows that a significant proportion of patients with hand osteoarthritis and psoriatic arthritis with moderate pain intensity have significantly increased signs of pain sensitization and markers of psychological distress. A large proportion of these patients fulfil the criteria for concomitant fibromyalgia and these patients show even greater propensity towards pain sensitization and psychological distress.

Application of PainDETECT in pediatric chronic pain: how well does it identify neuropathic pain and its characteristics?

Introduction

Neuropathic pain (NP) arises from nerve damage or disease, and when not defined, it can impair function and quality of life. Early detection allows for interventions that can enhance outcomes. Diagnosis of NP can be difficult if not properly evaluated. PainDETECT is a NP screening tool developed and successfully used in adults.

Objectives

We evaluated the validity of painDETECT in a pediatric population.

Methods

Adolescents and young adults (10-19 years old) completed painDETECT and quantitative sensory testing (QST), which assessed mechanical allodynia and hyperalgesia, common symptoms of NP. Pain diagnoses, including neuropathic pain (n = 10), were collected through documentation in the medical chart. Descriptive statistics were used to examine age, gender, pain diagnoses, and painDETECT scores. Kruskal-Wallis H tests were conducted to examine differences in QST results across painDETECT categorizations.

Results

Youth with chronic pain (N = 110, Mage = 15.08 ± 2.4 years, Nfemale = 88) and peers without pain (N = 55, Mage = 15.84 ± 3.9 years, Nfemale = 39) completed the painDETECT. The painDETECT scores for youth with pain (M = 12.7 ± 6.76) were significantly higher than those for peers without pain (M = 2.05 ± 2.41). PainDETECT demonstrated 80% sensitivity and 33% specificity in a pediatric population. Individuals who screened positively on the PainDETECT had significantly higher mechanical allodynia (M = 0.640 ± 0.994) compared with those who screened negatively (M = 0.186 ± 0.499; P = 0.016).

Conclusion

PainDETECT demonstrated the ability to screen for NP, and QST mechanical allodynia results were consistent with a positive NP screen. Results of the study offer preliminary support for the ongoing assessment of the painDETECT as a brief, inexpensive, and simple-to-use screening tool for pediatric patients with primary pain complaints.

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.

Understanding the Psychophysiological and Sensitization Mechanisms Behind Fibromyalgia Syndrome: A Network Analysis Approach

OBJECTIVE

Current evidence suggests that fibromyalgia syndrome (FMS) involves complex underlying mechanisms. This study aimed to quantify the multivariate relationships between clinical, psychophysical, and psychological outcomes in women with FMS by using network analysis to understand the psychobiological mechanisms driving FMS and generating new research questions for improving treatment strategies.

METHODS

Demographic (age, height, weight), clinical (pain history, pain intensity at rest and during daily living activities), psychophysical (widespread pressure pain thresholds [PPT]), sensory-related (PainDETECT, S-LANSS, Central Sensitization Inventory [CSI]) and psychological (depressive and anxiety levels) variables were collected in 126 women with FMS. Network analysis was conducted to quantify the adjusted correlations between the modeled variables and to assess their centrality indices (i.e., the connectivity with other symptoms in the network and the importance in the system modelled as network).

RESULTS

The network showed several local associations between psychophysical and clinical sensory-related variables. Multiple positive correlations between PPTs were observed, being the strongest weight between PPTs on the knee and tibialis anterior muscle (ρ: 0.33). PainDETECT was associated with LANSS (ρ: 0.45) and CSI (ρ: 0.24), whereas CSI was associated with HADS-A (ρ: 0.28). The most central variables were PPTs over the tibialis anterior (the highest Strength centrality) and CSI (the highest Closeness and Betweenness centrality).

CONCLUSION

Our findings support a model where clinical sensory-related, psychological, and psycho-physical variables are connected, albeit in separate clusters, reflecting a nociplastic condition with a relevant role of sensitization. Clinical implications of the findings, such as developing treatments targeting these mechanisms, are discussed.

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.

Bayesian Linear Regressions Applied to Fibromyalgia Syndrome for Understanding the Complexity of This Disorder

A better understanding of the connection between factors associated with pain sensitivity and related disability in people with fibromyalgia syndrome may assist therapists in optimizing therapeutic programs. The current study applied mathematical modeling to analyze relationships between pain-related, psychological, psychophysical, health-related, and cognitive variables with sensitization symptom and related disability by using Bayesian Linear Regressions (BLR) in women with fibromyalgia syndrome (FMS). The novelty of the present work was to transfer a mathematical background to a complex pain condition with widespread symptoms. Demographic, clinical, psychological, psychophysical, health-related, cognitive, sensory-related, and related-disability variables were collected in 126 women with FMS. The first BLR model revealed that age, pain intensity at rest (mean-worst pain), years with pain (history of pain), and anxiety levels have significant correlations with the presence of sensitization-associated symptoms. The second BLR showed that lower health-related quality of life and higher pain intensity at rest (mean-worst pain) and pain intensity with daily activities were significantly correlated with related disability. These results support an application of mathematical modeling for identifying different interactions between a sensory (i.e., Central Sensitization Score) and a functional (i.e., Fibromyalgia Impact Questionnaire) aspect in women with FMS.

Association of Neuropathic Pain Symptoms with Sensitization Related Symptomatology in Women with Fibromyalgia

We aimed to analyze potential correlations between S-LANSS and PainDETECT with proxies for pain sensitization, e.g., the Central Sensitization Inventory (CSI) and pressure pain hyperalgesia (construct validity), pain-related or psychological variables (concurrent validity) in women with fibromyalgia (FMS). One-hundred-and-twenty-six females with FMS completed demographic, pain-related variables, psychological, and sensitization outcomes as well as the S-LANSS and the PainDETECT questionnaires. S-LANSS was positively associated with BMI (r = 0.206), pain intensity (r = 0.206 to 0.298) and CSI score (r = 0.336) and negatively associated with all PPTs (r = -0.180 to -0.336). PainDETECT was negatively associated with age (r = -0.272) and all PPTs (r = -0.226 to -0.378) and positively correlated with pain intensity (r = 0.258 to 0.439), CSI (r = 0.538), anxiety (r = 0.246) and depression (r = 0.258). 51.4% of the S-LANSS was explained by PainDETECT (45.3%), posterior iliac PPT (0.2%) and mastoid PPT (5.9%), whereas the 56.4% of PainDETECT was explained by S-LANSS (43.4%), CSI (10.4%), and pain intensity (2.6%). This study found good convergent association between S-LANSS and PainDETECT in women with FMS. Additionally, S-LANSS was associated with PPTs whereas PainDETECT was associated with pain intensity and CSI, suggesting that both questionnaires assess different spectrums of the neuropathic and pain sensitization components of a condition and hence provide synergistic information.

Scoping review and interpretation of myofascial pain/fibromyalgia syndrome: An attempt to assemble a medical puzzle

BACKGROUND

Myofascial Pain Syndrome (MPS) is a common, overlooked, and underdiagnosed condition and has significant burden. MPS is often dismissed by clinicians while patients remain in pain for years. MPS can evolve into fibromyalgia, however, effective treatments for both are lacking due to absence of a clear mechanism. Many studies focus on central sensitization. Therefore, the purpose of this scoping review is to systematically search cross-disciplinary empirical studies of MPS, focusing on mechanical aspects, and suggest an organic mechanism explaining how it might evolve into fibromyalgia. Hopefully, it will advance our understanding of this disease.

METHODS

Systematically searched multiple phrases in MEDLINE, EMBASE, COCHRANE, PEDro, and medRxiv, majority with no time limit. Inclusion/exclusion based on title and abstract, then full text inspection. Additional literature added on relevant side topics. Review follows PRISMA-ScR guidelines. PROSPERO yet to adapt registration for scoping reviews.

FINDINGS

799 records included. Fascia can adapt to various states by reversibly changing biomechanical and physical properties. Trigger points, tension, and pain are a hallmark of MPS. Myofibroblasts play a role in sustained myofascial tension. Tension can propagate in fascia, possibly supporting a tensegrity framework. Movement and mechanical interventions treat and prevent MPS, while living sedentarily predisposes to MPS and recurrence.

CONCLUSIONS

MPS can be seen as a pathological state of imbalance in a natural process; manifesting from the inherent properties of the fascia, triggered by a disrupted biomechanical interplay. MPS might evolve into fibromyalgia through deranged myofibroblasts in connective tissue ("fascial armoring"). Movement is an underemployed requisite in modern lifestyle. Lifestyle is linked to pain and suffering. The mechanism of needling is suggested to be more mechanical than currently thought. A "global percutaneous needle fasciotomy" that respects tensegrity principles may treat MPS/fibromyalgia more effectively. "Functional-somatic syndromes" can be seen as one entity (myofibroblast-generated-tensegrity-tension), sharing a common rheuma-psycho-neurological mechanism.

Prognostic factors for work disability in patients with chronic widespread pain and fibromyalgia: protocol for a cohort study

INTRODUCTION

The association between chronic widespread pain (CWP) and disability is well established. Although research support large interindividual differences in functional outcomes, limited studies are available on the socio-economic consequences of offering stratified treatment based on prognostic factors. Identification of predictors of long-term functional outcomes such as work disability as a critical consequence, could assist early and targeted personalised interventions. The primary objective of this cohort study is to identify prognostic factors for the primary endpoint work status (employed and working vs not working) in patients with CWP assessed 3 years from baseline, that is, at referral for specialist care.

METHODS AND ANALYSES

Data are collected at the diagnostic unit at Department of Rheumatology, Frederiksberg Hospital. The first 1000 patients ≥18 years of age registered in a clinical research database (DANFIB registry) with CWP either 'employed and working' or 'not working' will be enrolled. Participants must meet the American College of Rheumatology 1990 definition of CWP, that is, pain in all four body quadrants and axially for more than 3 months and are additionally screened for fulfilment of criteria for fibromyalgia. Clinical data and patient-reported outcomes are collected at referral (baseline) through clinical assessment and electronic questionnaires. Data on the primary endpoint work status at baseline and 3 years from baseline will be extracted from the Integrated Labour Market Database, Statistics Denmark and the nationwide Danish DREAM database. Prognostic factor analysis will be based on multivariable logistic regression modelling with the dichotomous work status as dependent variable.

ETHICS AND DISSEMINATION

Sensitive personal data will be anonymised according to regulations by the Danish Data Protection Agency, and informed consent are obtained from all participants. Understanding and improving the prognosis of a health condition like CWP should be a priority in clinical research and practice. Results will be published in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04862520.

Efficacy of Repetitive Transcranial Magnetic Stimulation in Fibromyalgia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

This article aimed to investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in fibromyalgia. The PubMed, Medline, Cochrane Library, and Web of Science databases were searched for articles published through 14 August 2021. We enrolled only randomized controlled trials. The Cochrane Collaboration risk of bias tool was used for quality assessment. Outcomes were analyzed as standardized mean differences (SMDs) with 95% CIs. The beta coefficient and p value were adopted for meta-regression. We included 18 studies comprising 643 participants. A significant reduction in disease influence, as measured by the Fibromyalgia Impact Questionnaire, was observed (SMD, −0.700, 95% CI, −1.173 to −0.228), and the reduction was larger in older patients (β = −0.1327, p = 0.008). The effect persisted at least two weeks after the final treatment session (SMD, −0.784, 95% CI, −1.136 to −0.432). Reductions in pain, depression, and anxiety were discovered, which persisted for at least two weeks after the last intervention. The effects on pain and depression remained significant up to one and a half months after the final session. No serious adverse events were reported by the included articles. In conclusion, our systematic review and meta-analysis revealed that rTMS is safe and effective for managing multiple domains of fibromyalgia-related symptoms and older patients may have a stronger treatment effect. Larger randomized controlled trials with sufficient male populations are warranted to confirm our findings, detect rare adverse events, and determine the optimal stimulation parameters.

Exponential correlations among neuropathic components, pain intensity, and catastrophic thoughts in patients with musculoskeletal pain disorder

BACKGROUND

Neuropathic components and catastrophic thoughts contribute to the quality of life impairments in patients with chronic pain. This retrospective cross-sectional observational study examined the extent to which neuropathic components affect pain intensity and catastrophic thoughts using a mathematical model.

METHODS

Participants with chronic pain with spinal or joint disorders were rated for pain intensity using a numerical rating scale (NRS), painDETECT questionnaire (PDQ), and pain catastrophizing scale (PCS). We plotted to scatter plots between PDQ and either NRS or PCS and drew best-fit lines for patients with leg pain only. We divided patients with both leg and back pain into two clusters: located above or below the baselines, and then we drew the best-fit lines for each cluster. We performed factor analysis on PDQ items and developed and validated a discriminant to identify patients located above the baseline in another cohort of musculoskeletal disorders.

RESULTS

We analyzed 163 patients with lumbar disorders and 205 patients with joint disorders. PDQ correlated exponentially with NRS and PCS of the patients located above the baseline in both disorder groups and correlated linearly or logarithmically in patients located below the baseline. Factor analysis revealed three sets of pain characteristics for each disorder. We developed the discriminant from PDQ items to identify patients showing exponential correlations and then validated it in another cohort of 137 patients. The coefficient for "pressure-evoked pain" was the highest in the discriminant.

CONCLUSIONS

Mathematical models indicate neuropathic components demonstrate linear correlations with NRS and PCS generally, but exponential correlations in a cluster of the patients with musculoskeletal pain. We developed and validated the discriminant based on pain characteristics to identify such patients; "pressure-evoked pain" was the most significant contributor.

Mast cell stabilizer ketotifen fumarate reverses inflammatory but not neuropathic-induced mechanical pain in mice

Supplemental Digital Content is Available in the Text.

Our preclinical findings indicate that ketotifen fumarate's analgesic effects are MC-dependent, and the case series report presented supports its use for the treatment of chronic pain.

Introduction:

Mast cell (MC) activation could establish a positive feedback loop that perpetuates inflammation and maintains pain. Stabilizing MCs with ketotifen fumarate (KF) may disrupt this loop and relieve pain.

Objective:

We aimed to test the effect of treatment with KF in pain assays in mice and in a case series of patients with chronic widespread pain.

Methods:

The analgesic effect of KF was tested in CD-1 mice injected with formalin, complete Freund's adjuvant, or subjected to spared nerve injury. In addition, wild-type (C57BL/6) and MC-deficient (C57BL/6-Kit^W-sh/W-sh) mice were injected with formalin or complete Freund's adjuvant and treated with KF. Patients with chronic widespread pain (n = 5; age: 13–16 years) who failed to respond to standard of care participated in a 16-week treatment trial with KF (6 mg/d). Ketotifen fumarate's therapeutic effect was evaluated using the patient global impression of change.

Results:

In the mouse experiments, KF produced dose- and MC-dependent analgesic effects against mechanical allodynia in the acute and chronic inflammatory pain but not neuropathic pain assays. In the patient case series, 4 patients reported that activity limitations, symptoms, emotions, and overall quality of life related to their pain condition were “better” or “a great deal better” since beginning treatment with KF. This was accompanied by improvements in pain comorbid symptoms.

Conclusion:

Treatment with KF is capable of reducing established inflammatory-induced mechanical nociception in an MC-dependent manner in mice, and it may be beneficial for the treatment of chronic pain conditions.

Brief Self-Compassion Training Alters Neural Responses to Evoked Pain for Chronic Low Back Pain: A Pilot Study

OBJECTIVE

Self-compassion meditation, which involves compassion toward the self in moments of suffering, shows promise for improving pain-related functioning, but its underlying mechanisms are unknown. This longitudinal, exploratory pilot study investigated the effects of a brief (eight contact hours, two weeks of home practice) self-compassion training on pain-related brain processing in chronic low back pain (cLBP).

METHODS

We evaluated functional magnetic resonance imaging (fMRI) response to evoked pressure pain and its anticipation during a self-compassionate state and compared altered brain responses following training with changes on self-reported measures of self-compassion (Self-Compassion Scale [SCS]), interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness [MAIA]), and clinical pain intensity.

RESULTS

In a sample of participants with cLBP (N = 20 total, N = 14 with complete longitudinal data) who underwent self-compassion training, we observed reduced clinical pain intensity and disability (P < 0.01) and increased trait self-compassion and interoceptive awareness (all P < 0.05) following training. Evoked pressure pain response in the right temporo-parietal junction (TPJ) was reduced following training, and decreases were associated with reduced clinical pain intensity. Further, increased fMRI responses to pain anticipation were observed in the right dorsolateral prefrontal cortex (dlPFC) and ventral posterior cingulate cortex (vPCC), and these increases were associated with mean post-training changes in SCS scores and scores from the body listening subscale of the MAIA.

DISCUSSION

These findings, though exploratory and lacking comparison with a control condition, suggest that self-compassion training supports regulation of pain through the involvement of self-referential (vPCC), salience-processing (TPJ), and emotion regulatory (dlPFC) brain areas. The results also suggest that self-compassion could be an important target in the psychotherapeutic treatment of cLBP, although further studies using controlled experimental designs are needed to determine the specificity of these effects.

Chronic Pain and Assessment of Pain Sensitivity in Patients With Axial Spondyloarthritis: Results From the SPARTAKUS Cohort

OBJECTIVE

To study differences in pain reports between patients with ankylosing spondylitis (AS) and nonradiographic axial spondyloarthritis (nr-axSpA), and to assess how pain sensitivity measures associate with disease and health outcomes.

METHODS

Consecutive patients with axial SpA (axSpA) were enrolled in the population-based SPARTAKUS cohort (2015-2017) and classified as AS (n = 120) or nr-axSpA (n = 55). Pain was assessed with questionnaires (intensity/duration/distribution) and computerized cuff pressure algometry to measure pain sensitivity (pain threshold/pain tolerance/temporal summation of pain). Linear regression models were used to compare pain measures between patients with AS and nr-axSpA, and to assess associations between pain sensitivity measures and disease and health outcomes.

RESULTS

Of 175 patients with axSpA, 43% reported chronic widespread pain, with no significant differences in any questionnaire-derived or algometry-assessed pain measures between patients with AS and nr-axSpA. Lower pain tolerance was associated with longer symptom duration, worse Ankylosing Spondylitis Disease Activity Score using C-reactive protein (ASDAS-CRP), Bath Ankylosing Spondylitis Functional Index, and Bath Ankylosing Spondylitis Metrology Index (BASMI), more pain regions, unacceptable pain, worse Maastricht AS Enthesitis Score (MASES), fatigue, anxiety, and health-related quality of life. Further, lower pain threshold was associated with worse ASDAS-CRP and MASES, whereas higher temporal summation was associated with longer symptom duration, unacceptable pain, and worse BASMI.

CONCLUSION

Chronic pain is common in axSpA, with no observed differences in any pain measures between patients with AS and nr-axSpA. Further, higher pain sensitivity is associated with having worse disease and health outcomes. The results indicate that patients with AS and nr-axSpA, in line with most clinical characteristics, have a similar pain burden, and they highlight large unmet needs regarding individualized pain management, regardless of axSpA subgroup.

Neuropathic-like pain in psoriatic arthritis: evidence of abnormal pain processing

OBJECTIVES

The primary objective was to investigate the prevalence of neuropathic-like pain in patients with psoriatic arthritis (PsA). Secondary outcomes were to investigate whether mood, fatigue, pain, disease severity and fibromyalgia are associated with neuropathic-like pain in PsA patients.

METHODS

PsA patients were assessed for fatigue, mood, pain, disease activity and fibromyalgia using questionnaires. Neuropathic-like pain was assessed by PainDetect.

RESULTS

Sixty-four patients with PsA were recruited from the Rheumatology Outpatient Department. Of the 64 patients recruited, 26.6% had 'likely neuropathic pain' and 21.9% had 'possible neuropathic-like pain' according to the PainDetect questionnaire. Patients with 'likely neuropathic pain' had higher disease activity, health assessment questionnaire, patient global self-assessment score, tender and swollen joint counts, dactylitis, enthesitis, pain severity and interference with day-to-day activities, fatigue severity and impact, fibromyalgia, anxiety and depression than 'unlikely neuropathic pain' patients (p < 0.05). PainDetect score correlated with measures of disease activity, fatigue, depression, anxiety, Widespread Pain Index and Symptom Severity Scale (all p < 0.05). Most patients (71%) with neuropathic-like pain fulfilled American College of Rheumatology 2010 fibromyalgia criteria. Patients with 'possible neuropathic-like pain' had scores between patients with 'likely neuropathic pain' and 'unlikely neuropathic pain'.

CONCLUSION

Neuropathic-like pain as evidence of abnormal pain processing is common in patients with PsA. It is associated with higher disease activity and fibromyalgia. A significant proportion of patients had 'possible neuropathic-like' pain with intermediate disease and symptom score suggesting neuropathic-like pain as evidence of abnormal pain processing is a continuum rather than concurrent fibromyalgia. Key Points • Neuropathic pain is prevalent in psoriatic arthritis. • Higher levels of pain, disease activity, fatigue, depression, anxiety and comorbidities in Psoriatic arthritis. • Increased pain severity is associated with increased disease activity, fatigue, depression and anxiety.

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 relationship between regional pain with or without neuropathic symptoms and chronic widespread pain

Neuropathic pain was relatively rare and predicted a small number of chronic widespread pain cases. Using these estimates, treatments targeting neuropathic pain would at best prevent 6% of chronic widespread pain cases.

This study was performed to test whether the risk of developing chronic widespread pain (CWP) in those with regional pain was augmented in those with symptoms of neuropathic pain (NP). Persons free of CWP completed the Douleur Neuropathique 4 (scores ≥3 indicating NP); demographics; Hospital Anxiety and Depression scale; Pittsburgh Sleep Quality Index; and pain medications. Participants were classified as having no pain, regional pain with no symptoms of NP (), or regional pain with symptoms of NP (NP). At the 12-month follow-up, participants with CWP were identified. Logistic regression estimated the odds ratio, with 95% confidence intervals, of CWP in the and NP groups compared with no pain, and NP compared with . Partial population attributable risks estimated the proportion of CWP attributable to baseline or NP exposure. One thousand one hundred sixty-two participants completed the baseline DN4 and provided pain data at follow-up: 523 (45.0%) had no baseline pain, 562 (48.4%) , and 77 (6.6%) NP. One hundred fifty-three (13.2%) had CWP at 12 months: 19 (3.6%) no pain, 108 (19.2%) , and 26 (33.8%) NP. (2.9 [1.9-4.3]) and NP (2.1 [1.1-4.0]) predicted CWP after adjusting for demographics, Hospital Anxiety and Depression scale, Pittsburgh Sleep Quality Index, and medications. The partial population attributable risk was 41.3% (25.2-54.0) for and 6.0% (0.1-11.6) for NP. The NP group were not more likely to develop CWP when compared directly with (1.5 [0.8-2.8]). Neuropathic pain was relatively rare and predicted a small number of new-onset CWP cases. Using these estimates, treatments targeting NP would at best prevent 6% of CWP cases.

Pain assessment in Spanish rheumatology outpatient clinics: EVADOR Study

INTRODUCTION

rheumatic diseases are the most frequent cause of non-malignant chronic pain. In recent years, pain and its management have become more important in rheumatology.

OBJECTIVES

to estimate the prevalence and characteristics of pain associated with rheumatic pathology treated in rheumatology clinics in Spain, as well as their treatment and response to it.

METHODS

Multicentre observational study with two phases (cross-sectional and prospective). Variables were collected from the doctor, patient, pain and its management, comorbidities, therapeutic response and related psychosocial aspects. The differences between de novo (NP) vs follow-up (FP) patients were analyzed.

RESULTS

34 centres and 1084 patients were included, 32% NP and 68% FP. Pain was present in 86%, was chronic in 81% and neuropathic in 12% of the surveyed population. Fifty percent of the patients would regard their pain as tolerable if its intensity according to the visual numeric scale (VNS) was≤2. Among the FP it was more frequent to have the perception of controlled pain (65.5% vs 49.4%) and to be satisfied with the treatment (53.3% vs. 35.6%). Of these patients, 23.5% had been treated with opioids in the previous month.

CONCLUSIONS

In the last decade, the prevalence of pain in rheumatology in Spain remains high, although it has diminished. The use of opioids, on the other hand, has increased.

Pain Mechanisms and Ultrasonic Inflammatory Activity as Prognostic Factors in Patients With Psoriatic Arthritis: A Prospective Cohort Study

OBJECTIVE

To study the prognostic value of widespread pain and of musculoskeletal ultrasound (US) examination for subsequent treatment outcomes in patients with psoriatic arthritis (PsA).

METHODS

An exploratory prospective cohort study enrolled patients with PsA initiating biologic or conventional synthetic disease-modifying antirheumatic drugs in routine care. Clinical, US, and patient-reported measures were collected at baseline and after 4 months. Widespread nonarthritic pain (WP) was defined as a Widespread Pain Index score of ≥4 with pain in ≥4 of 5 regions. PsA activity by US was defined as color Doppler (yes/no) in selected entheses, joints, or tendons. The main response criteria included the American College of Rheumatology 20% improvement, the Disease Activity in Psoriatic Arthritis 50% improvement, and minimal disease activity. The primary analyses were age- and sex-adjusted logistic regression.

RESULTS

WP was present in 24 of 69 included patients (35%) and was associated with worse patient-reported and composite baseline measures, while US and other objective findings were similar to those in patients without WP. The odds of reaching minimal disease activity after 4 months were significantly greater for patients enrolled without WP (odds ratio 18.43 [95% confidence interval 1.51, 224.41]; P = 0.022), while WP did not impair other response measures. Patients with baseline color Doppler activity (n = 42 [61%]) had a worse objective PsA burden, but their chance of treatment response was comparable to those without color Doppler.

CONCLUSION

More than one-third of patients with PsA presented with WP, which was associated with worse patient-reported scores and failure to achieve minimal disease activity following conventional synthetic or biologic disease-modifying antirheumatic drug therapy. PsA activity by color Doppler US had no influence on subsequent treatment response in this PsA cohort.

Development and preliminary evaluation of a short self-report measure of generalized pain hypersensitivity

Purpose

Generalized pain hypersensitivity is frequently observed in chronic pain conditions. Currently, identification is based on expert clinical opinion, and in very few cases combined with quantitative sensory testing. The objectives of this study were to develop and evaluate a short self-report measure of generalized pain hypersensitivity: a generalized pain questionnaire (GPQ).

Methods

Items for the GPQ were developed based on a literature review, followed by an interview study with ten rheumatic patients with suspected pain hypersensitivity. We examined the psychometric properties of the preliminary items in a sample of 212 outpatients suffering from either fibromyalgia (FM; n=98) or rheumatoid arthritis (n=114). Additionally, self-reported data were gathered on sociodemographics, fibromyalgia-survey criteria, health status, and neuropathic-like pain features.

Results

Mokken-scale analyses demonstrated a unidimensional seven-item scale with strong homogeneity (H=0.65) and high reliability (r=0.90). Correlations between total GPQ scores and relevant external measures, such as the FM-survey criteria and neuropathic-like pain features, were consistent with a priori expectations, supporting its external construct validity. Furthermore, the GPQ had good accuracy in distinguishing between patients with FM (generally assumed to be the result of central nervous system hypersensitization) and patients with RA (assumed to result mostly in local nociceptive or inflammatory pain), with an area under the receiver-operating characteristic curve of 0.89. A cutoff value >10 had the highest combination of sensitivity (82.7%) and specificity (77.2%).

Conclusion

The GPQ is psychometrically sound and appears promising for measuring the presence and severity of generalized pain hypersensitivity in chronic pain patients.

Cuff Pressure Algometry in Patients with Chronic Pain as Guidance for Circumferential Tissue Compression for Wearable Soft Exoskeletons: A Systematic Review

In this article, we report on a systematic review of the literature on pressure-pain thresholds induced and assessed by computerized cuff pressure algometry (CPA). The motivation for this review is to provide design guidance on pressure levels for wearable soft exoskeletons and similar wearable robotics devices. In our review, we focus on CPA studies of patients who are candidates for wearable soft exoskeletons, as pain-related physiological mechanisms reportedly differ significantly between healthy subjects and patients with chronic pain. The results indicate that circumferential limb compression in patients most likely becomes painful at ∼10-18 kPa and can become unbearable even below 25 kPa. The corresponding ranges for healthy control subjects are 20-42 kPa (painful limits) and 34-84 kPa (unbearable levels). In addition, the increase of pain with time tends to be significantly higher, and the adaptation to pain significantly lower, than in healthy subjects. The results of this review provide guidance to designers of wearable robotics for populations with chronic pain regarding rates and magnitudes of tissue compression that may be unacceptable to users.

The course of pain hypersensitivity according to painDETECT in patients with rheumatoid arthritis initiating treatment: results from the prospective FRAME-cohort study

BACKGROUND

Evidence is emerging that pain in rheumatoid arthritis (RA) exists without underlying inflammation. Our objective was to evaluate the prognostic value of pain classification at treatment initiation using the painDETECT questionnaire (PDQ). Outcomes were change in DAS28-CRP and RAMRIS synovitis score.

METHODS

RA patients initiating a disease-modifying anti-rheumatic drug (DMARD) or initiating/ switching a biological agent were included. Follow-up time was 4 months. Clinical examination, imaging (MRI, dynamic contrast-enhanced MRI (DCE-MRI)), and patient-reported outcomes were undertaken. The PDQ was used to differentiate pain mechanisms. Mean change (95% CI) was calculated using ANCOVA. Multivariable regression models were used to determine a prognostic value.

RESULTS

A total of 102 patients were included; 75 were enrolled for MRI. Mean changes in baseline variables were greatest in the high PDQ classification group (> 18), while limited in the intermediate group (13-18). The 12 patients with high baseline PDQ score all changed pain classification group. No prognostic value of PDQ pain classification was found in relation to change of DAS28-CRP, RAMRIS score, or VAS pain. In the unadjusted model, RAMRIS score at baseline was associated with change in DAS28-CRP. The exploratory variables of DCE-MRI did not differ from other inflammatory variables.

CONCLUSIONS

In RA patients a high PDQ score (non-nociceptive pain) at baseline was not associated with worse outcomes, in fact these patients had numerically greater improvement in DAS28-CRP. However, pain classification by PDQ was not independently associated with change in DAS28-CRP, RAMRIS score, or VAS pain in the prognostic models. Furthermore, patients classified with a high baseline PDQ score changed pain classification group. Patients with unclear pain mechanism had reduced numerically treatment response.

TRIAL REGISTRATION

The study was approved by the Regional Ethics Committee of the Capital of Denmark April 18 2013; identification number H-3-2013-049 .

Identification of FAM173B as a protein methyltransferase promoting chronic pain

Chronic pain is a debilitating problem, and insights in the neurobiology of chronic pain are needed for the development of novel pain therapies. A genome-wide association study implicated the 5p15.2 region in chronic widespread pain. This region includes the coding region for FAM173B, a functionally uncharacterized protein. We demonstrate here that FAM173B is a mitochondrial lysine methyltransferase that promotes chronic pain. Knockdown and sensory neuron overexpression strategies showed that FAM173B is involved in persistent inflammatory and neuropathic pain via a pathway dependent on its methyltransferase activity. FAM173B methyltransferase activity in sensory neurons hyperpolarized mitochondria and promoted macrophage/microglia activation through a reactive oxygen species–dependent pathway. In summary, we uncover a role for methyltransferase activity of FAM173B in the neurobiology of pain. These results also highlight FAM173B methyltransferase activity as a potential therapeutic target to treat debilitating chronic pain conditions.

Pain is an evolutionarily conserved physiological phenomenon necessary for survival. Yet, pain can become pathological when it occurs independently of noxious stimuli. The molecular mechanisms of pathological pain are still poorly understood, limiting the development of highly needed novel analgesics. Recently, genetic variations in the genomic region encoding FAM173B—a functionally uncharacterized protein—have been linked to chronic pain in humans. In this study, we identify the role and function of FAM173B in the development of pathological pain. We used genetic, biochemical, and behavioral approaches in mice to show that FAM173B is a mitochondrial lysine methyltransferase—a protein that transfers methyl group to donor proteins. By genetically silencing or overexpressing FAM173B in sensory neurons, we showed that FAM173B methyltransferase activity promotes the development of chronic pain. In addition, we discovered that FAM173B methyltransferase activity in the mitochondria of sensory neurons promotes chronic pain via a pathway that depends on the production of reactive oxygen species and on the engagement of spinal cord microglia—engulfing cells of the central nervous system. These data point to an essential role of FAM173B in the regulation of pathological pain.

Patients with Concomitant Chronic Neck Pain and Myofascial Pain in Masticatory Muscles Have More Widespread Pain and Distal Hyperalgesia than Patients with Only Chronic Neck Pain

Objective

Insufficient evidence exists to compare widespread pain (WP), pain sensibility, and psychological factors that occur in patients presenting with chronic neck pain (CNP) or a combination of temporomandibular disorder (TMD) and other complaints. The present study compared the pain sensibility and psychological factors of subjects with CNP with those with TMD + CNP.

Design

Cross-sectional study.

Setting

Local community.

Subjects

A nonprobabilistic convenience sample of 86 persons with CNP or TMD was recruited into three groups: CNP, TMD with myofascial pain in masticatory muscles with cocomitant CNP (TMD + CNP), and asymptomatic control groups consisted of 27, 29, and 30 participants, respectively.

Methods

Participants underwent a clinical examination to evaluate WP with computerized assessment based on the pain drawing, pressure pain thresholds (PPT), and psychological factors, which were evaluated using the pain catastrophizing scale (PCS) and the state-trait anxiety inventory (STAI).

Results

Statistically significant differences were observed between participants with CNP and TMD + CNP for WP (t = -2.80, P  < 0.01, d = -1.06). Post hoc analyses only revealed significant differences between TMD + CNP participants and asymptomatic controls for PPT at extratrigeminal areas. Pearson correlation analyses showed a moderate positive association between symptomatic groups within the WP and STAI ( P  < 0.05) and a moderate negative association between PCS and PPT ( P  < 0.05) at the right tibialis muscle.

Conclusion

TMD + CNP participants had more areas of pain and also showed widespread pain hyperalgesia. Both groups of participants had psychological factors positively associated with STAI and WP; further, PCS and the PPT at the extratrigeminal region were negatively associated with each other in both groups, except for the left tibialis in the TMD + CNP group.

Pain experiences of patients with musculoskeletal pain + central sensitization: A comparative Group Delphi Study

Objectives

Central sensitization (CS) is regarded as an important contributing factor for chronification of musculoskeletal pain (MSP). It is crucial to identify CS, as targeted multimodal treatment may be indicated. The primary objective of this study was therefore to explore pain experience of individuals with MSP+CS in order to gain a better understanding of symptoms in relation to CS from a patient perspective. The secondary objective was to investigate whether pain experiences of patients with MSP+CS differ from those of individuals with neuropathic pain (NP).

Methods

We conducted a comparative Group Delphi Study including patients with MSP+CS and neuropathic pain (NP). 13 guiding questions were used to gather information about sensory discriminatory, affective and associated bodily, mental and emotional phenomena related to the pain experience of patients. Descriptions were categorized using qualitative content analysis. Additionally, patients completed several pain related questionnaires.

Results

Nine participants with MSP+CS and nine participants with NP participated. The Delphi procedure revealed three main themes: psycho-emotional factors, bodily factors and environmental factors. Descriptions of patients with MSP+CS showed a complex picture, psycho-emotional factors seem to have a considerable impact on pain provocation, aggravation and relief. Impairments associated with mental ability and psyche affected many aspects of daily life. In contrast, descriptions of patients with NP revealed a rather mechanistic and bodily oriented pain experience.

Discussion

Patients with MSP+CS reported distinct features in relation to their pain that were not captured with current questionnaires. Insight in patient’s pain experience may help to choose and develop appropriate diagnostic instruments.

Pain and pain mechanisms in patients with inflammatory arthritis: A Danish nationwide cross-sectional DANBIO registry survey

Background

Central pain mechanisms may be prominent in subsets of patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and other spondyloarthritis (SpA). The painDETECT questionnaire (PDQ) identifies neuropathic pain features, which may act as a proxy for centrally mediated pain.

The objectives were to quantify and characterize pain phenotypes (non-neuropathic vs. neuropathic features) among Danish arthritis patients using the PDQ, and to assess the association with on-going inflammation.

Methods

The PDQ was included onto the DANBIO touch screens at 22 departments of Rheumatology in Denmark for six months. Clinical data and patient reported outcomes were obtained from DANBIO. A PDQ-score >18 indicated neuropathic pain features, 13–18 unclear pain mechanism and <13 non-neuropathic pain.

Results

Pain data (visual analogue scale, VAS) was available for 15,978 patients. 7,054 patients completed the PDQ (RA: 3,826, PsA: 1,180, SpA: 1,093). 52% of all patients and 63% of PDQ-completers had VAS pain score ≥ 30 mm. The distribution of the PDQ classification-groups (<13/ 13-18/ >18) were; RA: 56%/24%/20%. PsA: 45%/ 27%/ 28%. SpA: 55% / 24%/ 21%. More patients with PsA had PDQ score >18 compared to RA and SpA (p<0.001). For PDQ > 18 significantly higher scores were found for all patient reported outcomes and disease activity scores. No clinical difference in CRP or swollen joint count was found. Logistic regression showed increased odds for having VAS pain ≥39 mm (the median) for a PDQ-score >18 compared to <13 (OR = 10.4; 95%CI 8.6–12.5).

Conclusions

More than 50% of the Danish arthritis patients reported clinically significant pain. More than 20% of the PDQ-completers had indication of neuropathic pain features, which was related to a high pain-level. PDQ-score was associated with DAS28-CRP and VAS pain but not with indicators of peripheral inflammation (CRP and SJC). Thus, pain classification by PDQ may assist in mechanism-based pain treatment.

Psychometric properties of the painDETECT questionnaire in rheumatoid arthritis, psoriatic arthritis and spondyloarthritis: Rasch analysis and test-retest reliability

Background

Pain is inherent in rheumatoid arthritis (RA), psoriatic arthritis (PsA) and spondyloarthritis (SpA) and traditionally considered to be of nociceptive origin. Emerging data suggest a potential role of augmented central pain mechanisms in subsets of patients, thus, valid instruments that can identify underlying pain mechanisms are needed. The painDETECT questionnaire (PDQ) was originally designed to differentiate between pain phenotypes. The objectives were to evaluate the psychometric properties of the PDQ in patients with inflammatory arthritis by applying Rasch analysis and to explore the reliability of pain classification by test-retest.

Methods

For the Rasch analysis 900 questionnaires from patients with RA, PsA and SpA (300 per diagnosis) were extracted from ‘the DANBIO painDETECT study’. The analysis was directed at the seven items assessing somatosensory symptoms and included: 1) the performance of the six-category Likert scale; 2) whether a unidimensional construct was defined; 3) the reliability and precision of estimates. Another group of 30 patients diagnosed with RA, PsA or SpA participated in a test-retest study. Intraclass Correlation Coefficients (ICC) and classification consistency were calculated.

Results

The Rasch analysis revealed: (1) Acceptable psychometric rating scale properties; the frequency distribution peaked in category 0 except for item 5, threshold calibration >10 observations per category, no disorder in the category measures for all items, scale category outfit Mnsq <2.0, small distances (<1.4 logits) between thresholds for category 1, 2 and 3 for all items. (2) The principal component analysis supported unidimensionality; the standardized residuals showed that 53.7% of total variance was explained by the measure and the magnitude of first contrast had an eigenvalue of 1.5, no misfitting items, clinical insignificant different item hierarchies across diagnoses (DIF < 0.5 logits). (3) A targeted item-person map, person and item separation indices of 1.88(reliability = 0.78), and 13.04 (reliability = 0.99). The test-retest revealed: ICC: RA 0.86(0.56–0.96), PsA 0.96(0.74–0.99), SpA 0.93(0.76–98), overall 0.94(0.84–0.98). Classification consistency was: RA 70%, PsA 80%, SpA 90%, overall 80%.

Conclusion

The results support that the PDQ can be used as a classification instrument and assist identification of underlying pain-mechanisms in patients suffering from inflammatory arthritis.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

Brain morphological alternation in chronic pain patients with neuropathic characteristics

Background

Neuropathic characteristics are highly involved in the development of chronic pain both physically and psychologically. However, little is known about the relationship between neuropathic characteristics and brain morphological alteration.

Objectives

The aim of this study is to investigate the mechanisms of chronic pain development by examining the above-mentioned relationships by voxel-based morphometry in patients with chronic pain.

Methods

First, we assessed neuropathic characteristics using the painDETECT Questionnaire in 12 chronic pain patients. Second, to assess the gray matter volume changes by voxel-based morphometry, we conducted magnetic resonance imaging of the brain. We applied multiregression analysis of these two assessment methods.

Results

There were significant positive correlations between painDETECT Questionnaire scores and the gray matter volume in the bilateral anterior cingulate cortex and right posterior cingulate cortex.

Conclusions

Our findings suggest that neuropathic characteristics strongly affect the brain regions related to modulation of pain in patients with chronic pain and, therefore, contribute to the severity of chronic pain.

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.

Pain mechanisms and ultrasonic inflammatory activity as prognostic factors in patients with psoriatic arthritis: protocol for a prospective, exploratory cohort study

INTRODUCTION

Persistent pain is a major concern for patients with psoriatic arthritis (PsA). Pain may be due to inflammatory activity or augmented central pain processing. Unawareness of the origin and mechanisms of pain can lead to misinterpretation of disease activity (by composite scores) and erroneous treatments. Ultrasonography (US) is a highly sensitive method to detect tissue inflammation. Evaluating pain mechanisms in relation to US measures may prove valuable in predicting response to treatment in PsA.

AIMS

To study the association and prognostic value of pain mechanisms, ultrasonic activity and clinical outcomes in patients with PsA who intensify antirheumatic treatment.

METHODS AND ANALYSES

100 participants >18 years of age with PsA who initiate or switch antirheumatic treatment (biologicals and/or conventional synthetic disease-modifying antirheumatic drugs (DMARDs)) will be prospectively recruited from outpatient clinics in Copenhagen. All data (demographics, clinical, imaging, blood samples and patient-reported outcomes) will be collected at baseline and after 4 months. Pain is assessed by the PainDETECT Questionnaire, Visual Analogue Scale for pain, Swollen to Tender Joint Count Ratio, Widespread Pain Index and tender point examination. The association between pain variables and clinical/US characteristics will be described by correlation analyses. The predictive value of pain measures and baseline US scores on treatment response will be analysed with regression models. Outcomes are composite and clinical, as well as patient reported.

ETHICS AND DISSEMINATION

The study is approved by the ethics committee of the Capital Region of Denmark (H-15009080) and has been designed in cooperation with patient research partners. The study is registered at clinicaltrials.gov (number NCT02572700). Results will be disseminated through publication in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02572700, Pre-results.

Scratching the surface: the processing of pain from deep tissues

Although most pain research focuses on skin, muscles, joints and viscerae are major sources of pain. We discuss the mechanisms of deep pains arising from somatic and visceral structures and how this can lead to widespread manifestations and chronification. We include how both altered peripheral and central sensory neurotransmission lead to deep pain states and comment on key areas such as top-down modulation where little is known. It is vital that the clinical characterization of deep pain in patients is improved to allow for back translation to preclinical models so that the missing links can be ascertained. The contribution of deeper somatic and visceral tissues to various chronic pain syndromes is common but there is much we need to know.

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.

Pain Sensitisation in Women with Active Rheumatoid Arthritis: A Comparative Cross-Sectional Study

Objectives. In some rheumatoid arthritis (RA) patients, joint pain persists without signs of inflammation. This indicates that central pain sensitisation may play a role in the generation of chronic pain in a subgroup of RA. Our aim was to assess the degree of peripheral and central pain sensitisation in women with active RA compared to healthy controls (HC). Methods. 38 women with active RA (DAS28 > 2.6) and 38 female HC were included in, and completed, the study. Exclusion criteria were polyneuropathy, pregnancy, and no Danish language. Cuff Pressure Algometry measurements were carried out on the dominant lower leg. Pain threshold, pain tolerance, and pain sensitivity during tonic painful stimulation were recorded. Results. Women with active RA had significantly lower pain threshold (p < 0.01) and pain tolerance (p < 0.01) than HC. The mean temporal summation- (TS-) index in RA patients was 0.98 (SEM: 0.09) and 0.71 (SEM: 0.04) in HC (p < 0.01). Conclusion. Patients with active RA showed decreased pressure-pain threshold compared to HC. In addition, temporal summation of pressure-pain was increased, indicating central pain sensitization, at least in some patients. Defining this subgroup of patients may be of importance when considering treatment strategies.

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.

Can the painDETECT Questionnaire score and MRI help predict treatment outcome in rheumatoid arthritis: protocol for the Frederiksberg hospital's Rheumatoid Arthritis, pain assessment and Medical Evaluation (FRAME-cohort) study

INTRODUCTION

Pain in rheumatoid arthritis (RA) is traditionally considered to be of inflammatory origin. Despite better control of inflammation, some patients still report pain as a significant concern, even when being in clinical remission. This suggests that RA may prompt central sensitisation-one aspect of chronic pain. In contrast, other patients report good treatment response, although imaging shows signs of inflammation, which could indicate a possible enhancement of descending pain inhibitory mechanisms. When assessing disease activity in patients with central sensitisation, the commonly used disease activity scores (eg, DAS28-CRP (C reactive protein)) will yield constant high total scores due to high tender joint count and global health assessments, whereas MRI provides an isolated estimate of inflammation. The objective of this study is, in patients with RA initiating anti-inflammatory treatment, to explore the prognostic value of a screening questionnaire for central sensitisation, hand inflammation assessed by conventional MRI, and the interaction between them regarding treatment outcome evaluated by clinical status (DAS28-CRP). For the purpose of further exploratory analyses, dynamic contrast-enhanced MRI (DCE-MRI) is performed.

METHOD AND ANALYSIS

The painDETECT Questionnaire (PDQ), originally developed to screen for a neuropathic pain component, is applied to indicate the presence of central sensitisation. Adults diagnosed with RA are included when either (A) initiating disease-modifying antirheumatic drug treatment, or (B) initiating or switching to biological therapy. We anticipate that 100 patients will be enrolled, tested and reassessed after 4 months of treatment.

DATA COLLECTION INCLUDES

Clinical data, conventional MRI, DCE-MRI, blood samples and patient-reported outcomes.

ETHICS AND DISSEMINATION

This study aims at supporting rheumatologists to define strategies to reach optimal treatment outcomes in patients with RA based on chronic pain prognostics. The study has been approved by The Capital region of Denmark's Ethics Committee; identification number H-3-2013-049. The results will be published in international peer-reviewed journals.

The Relationship between Mechanical Hyperalgesia Assessed by Manual Tender Point Examination and Disease Severity in Patients with Chronic Widespread Pain: A Cross-Sectional Study

The clinical utility of tender point (TP) examination in patients reporting chronic widespread pain (CWP) is the subject of contemporary debate. The objective of this study was to assess the relationship between mechanical hyperalgesia assessed by manual TP examination and clinical disease severity. 271 women with CWP were recruited from a clinical setting. Data collection included patient-reported symptoms, health-related quality of life variables, and observation-based measures of functional ability, muscle strength, 6-minute walk, and pressure pain thresholds measured by cuff algometry. TP examination was conducted according to ACR-guidelines. Relationships between disease variables and TP count (TPC) were analyzed with logistic regression in a continuum model, allowing the TPC to depend on the included disease variables and two regression models carried out for a TPC threshold level, varying between 1 and 17. The threshold analyses indicated a TPC threshold at 8, above which a large number of disease variables became consistently significant explanatory factors, whereas none of the disease variables reached a significance level in the continuum model. These results support the premise that the presence of mechanical hyperalgesia influences symptomatology in CWP and that the severity of clinical expression is related to a threshold of TPs, rather than being part of a continuum.