Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations

Describing the minimally clinically important difference of a chemotherapy-induced peripheral neuropathy patient-reported outcome measure in young adults

Objective

The purpose of this secondary analysis was to characterize the reliability, validity, and minimally clinically important difference (MCID) of change scores over time of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-CIPN-20 item (QLQ-CIPN20) in young adults receiving paclitaxel or vincristine.

Methods

Fifty young adults receiving vincristine or paclitaxel for the treatment of cancer completed the QLQ-CIPN20 at three time points associated with increasing cumulative chemotherapy dose. The Subject Significance Questionnaire was completed at T3. The analyses were focused on the calculation of floor and ceiling effects, internal consistency reliability, longitudinal validity, construct validity, and the MCID using an anchor-based approach for the QLQ-CIPN20 sensory and motor subscales.

Results

By T3, 50% and 52% of participants reported QLQ-CIPN20 sensory and motor subscale scores at the floor, respectively. The internal consistency reliability of the sensory (α ​= ​0.83) and motor (α ​= ​0.89) subscales was strong. The Cohen's d from T1 to T3 for the QLQ-CIPN20 sensory (d ​= ​-0.57) and motor (d ​= ​-0.47) subscales were small to moderate. There were low to moderate correlations between QLQ-CIPN20 sensory (r ​= ​0.45) and motor (r ​= ​0.27) subscale scores and vincristine cumulative dose. The MCID for worsening QLQ-CIPN20 sensory and motor subscale scores was 14.37 and 9.57, respectively (P ​< ​0.01).

Conclusions

Study results provided preliminary evidence surrounding the MCID for worsening of QLQ-CIPN20 scores using an anchor based on young adults' perceived change in CIPN severity. Further research is needed to develop psychometrically sound CIPN patient-reported outcome measures to effectively evaluate the impact of CIPN interventions among young adults.

Patient-reported outcomes, postoperative pain and pain relief after day case surgery (POPPY): methodology for a prospective, multicentre observational study

BACKGROUND

In the UK, approximately 70% of surgical procedures are undertaken as day-cases. Little information exists about recovery from day-case surgery, yet international data highlights patients are at risk of developing significant longer-term health problems including chronic post-surgical pain and persistent postoperative opioid use. The Patient-reported Outcomes, Postoperative Pain and pain relief after daY case surgery (POPPY) study was a national prospective multicentre observational study, measuring short- and longer-term patient-reported outcomes, postoperative pain and pain relief after day-case surgery.

METHODS

This was a collaborative project led by resident anaesthetists under the Research and Audit Federation of Trainees umbrella. Adult day-case surgical patients were recruited on the day of surgery. Baseline data including patient characteristics; procedure details; pre-operative analgesic use; pre-existing pain; and quality of life scores were recorded. Patients were followed up through automated short message service messages. Short-term (postoperative days 1, 3 and 7) outcomes included: quality of recovery; pain severity; impact of pain on function; and analgesic use. Longer-term outcomes (postoperative day 97) included: quality of life; analgesic use; incidence of chronic post-surgical pain; and incidence persistent postoperative opioid use. Additional outcomes were completed by those patients with chronic post-surgical pain and persistent postoperative opioid use, with 30 patients recruited to a qualitative semi-structured interview study exploring postoperative expectations, recovery, postoperative pain and opioid use.

RESULTS

An embedded pilot study at four sites recruited 129 patients. Responses to the automated short message service were gained from 129 patients (100%) at day 1; 116 (89.9%) at day 3; 108 (83.7%) at day 7; and 77 (59.7%) at day 97 postoperatively. The pilot enabled refinement of the methods and processes before the national roll out.

CONCLUSION

This paper outlines the methods for the POPPY study, the largest UK multicentre prospective observational study considering short- and longer-term outcomes following day-case surgery.

Rationale and design of a large trial of perioperative ketamine for prevention of chronic post-surgical pain

BACKGROUND

Chronic post-surgical pain (CPSP) is recognised as one of the most common and debilitating complications of major surgery. Progression from acute to chronic pain after surgery involves sensitisation of central nervous system pathways with the N-methyl-D-aspartate (NMDA) receptor having a central role. Ketamine is a potent, non-selective NMDA antagonist commonly used for management of acute postoperative pain. Inconsistent but largely supportive evidence from small trials of a preventative effect of perioperative ketamine on CPSP risk suggests that a confirmative large trial is needed.

METHODS

The ROCKet (Reduction Of Chronic Post-surgical Pain with Ketamine) Trial is a multicentre, double-blind, placebo-controlled, individually randomised superiority trial conducted in 36 hospitals across Australia, New Zealand, and Hong Kong. The trial aims to recruit 4884 patients undergoing abdominal, thoracic, or major orthopaedic surgery. Eligible participants are randomised equally to perioperative intravenous ketamine or placebo for up to 72 h. Incidence of pain in the area of the index surgery is measured by structured telephone interview at 3 months (primary trial endpoint) and 12 months. Pain severity, nature, and associated psychological and quality of life indices are measured using the modified Brief Pain Inventory short form, Neuropathic Pain Questionnaire, Kessler K-10 Psychological Distress Scale, Pain Catastrophising Scale, EQ-5D-3L, and measures of healthcare utilisation and costs. The trial is being conducted by the Department of Critical Care, University of Melbourne, and the Australian and New Zealand College of Anaesthetists Clinical Trials Network. The trial is funded by the Australian National Health and Medical Research Council.

DISCUSSION

The ROCKet trial will clarify the effectiveness of ketamine in primary prevention of CPSP. In addition, it will provide high-quality, prospective data on the epidemiology of CPSP which will better inform further research into prevention and management of CPSP.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12617001619336) on the date of 12/11/2017.

Emotions in search of words: Does alexithymia predict treatment outcome in chronic musculoskeletal pain?

Chronic pain, with its complex and multidimensional nature, poses significant challenges in identifying effective long-term treatments. There is growing scientific interest in how psychopathological and personality dimensions may influence the maintenance and development of chronic pain. This longitudinal study aimed to investigate whether alexithymia can predict the improvement of pain severity following a treatment-as-usual programme for chronic musculoskeletal pain over and above psychological cofactors (emotional distress, catastrophizing, and self-efficacy). A consecutive sample of 129 patients with diagnosed chronic musculoskeletal pain referred to two tertiary care centres was recruited and treated for 16 weeks. Clinical pain, psychological distress, self-efficacy, catastrophizing, and alexithymia were assessed with validated self-report measures at the first medical visit (T0) and at 16-week follow-up (T1). Compared with non-responder patients (n = 72, 55.8%), those who responded (i.e., reduction of >30% in pain severity; n = 57, 44.2%) reported an overall improvement in psychological variables except alexithymia. Alexithymia showed relative stability between baseline and follow-up within the entire sample and remained a significant predictor of treatment outcome even when other predictive cofactors (i.e., pain interference, depressive symptoms, and catastrophizing) were considered simultaneously. Our results suggest that identifying patients with a co-occurrence between alexithymia, depressive symptoms, catastrophizing, and the stressful experience of chronic pain can be clinically relevant in pain prevention and intervention programs.

Identifying and Evaluating Biological Markers of Postherpetic Neuralgia: A Comprehensive Review

Postherpetic neuralgia (PHN) manifests as persistent chronic pain that emerges after a herpes zoster outbreak and greatly diminishes quality of life. Unfortunately, its treatment efficacy has remained elusive, with many therapeutic efforts yielding less than satisfactory results. The research to discern risk factors predicting the onset, trajectory, and prognosis of PHN has been extensive. However, these risk factors often present as nonspecific and diverse, indicating the need for more reliable, measurable, and objective detection methods. The exploration of potential biological markers, including hematological indices, pathological insights, and supportive tests, is increasing. This review highlights potential biomarkers that are instrumental for the diagnosis, management, and prognosis of PHN while also delving deeper into its genesis. Drawing from prior research, aspects such as immune responsiveness, neuronal injury, genetic makeup, cellular metabolism, and pain signal modulation have emerged as prospective biomarkers. The immune spectrum spans various cell subtypes, with an emphasis on T cells, interferons, interleukins, and other related cytokines. Studies on nerve injury are directed toward pain-related proteins and the density and health of epidermal nerve fibers. On the genetic and metabolic fronts, the focus lies in the detection of predisposition genes, atypical protein manifestations, and energy-processing dynamics, with a keen interest in vitamin metabolism. Tools such as functional magnetic resonance imaging, electromyography, and infrared imaging have come to the forefront in the pain signaling domain. This review compiles the evidence, potential clinical implications, and challenges associated with these promising biomarkers, paving the way for innovative strategies for predicting, diagnosing, and addressing PHN.

Effectiveness of a specific follow up program for the management of the mental components of post-intensive care syndrome and chronic pain after COVID-19: results from the PAIN-COVID randomized clinical trial

BACKGROUND

Critical COVID-19 survivors are at risk of developing Post-intensive Care Syndrome (PICS) and Chronic ICU-Related Pain (CIRP). We determined whether a specific care program improves the quality of life (QoL) of patients at risk of developing PICS and CIRP after COVID-19.

METHODS

The PAIN-COVID trial was a parallel-group, single-centre, single-blinded, randomized controlled trial. The intervention consisted of a follow up program, patient education on PICS and pain, and a psychological intervention based on Rehm's self-control model in patients with abnormal depression scores (≥8) in the Hospital Anxiety and Depression Scale (HADS) at the baseline visit. QoL was evaluated with the 5-level EQ 5D (EQ 5D 5 L), mood disorders with the HADS, post-traumatic stress disorder (PTSD) with the PCL-5 checklist, and pain with the Brief Pain Inventory short form, the Douleur Neuropathique 4 questionnaire, and the Pain Catastrophizing Scale. The primary outcome was to determine if the program was superior to standard-of-care on the EQ visual analogue scale (VAS) at 6 months after the baseline visit. The secondary outcomes were EQ VAS at 3 months, and EQ index, CIRP incidence and characteristics, and anxiety, depression, and PTSD at 3 and 6 months after baseline visits.

CONCLUSIONS

This program was not superior to standard care in improving QoL in critical COVID-19 survivors as measured by the EQ VAS. However, our data can help establish better strategies for the study and management of PICS and CIRP in this population.

TRIAL REGISTRATION

# NCT04394169, registered on 5/19/2020.

Management of acute postoperative pain: Conditions to guarantee the safety and effectiveness of analgesic treatments

The evidence on postoperative pain management is of low or insufficient quality. The SEDAR Acute Pain Working Group has prepared this guideline-document to apply the best available scientific evidence to clinical practice, individualizing it based on factors specific to the patient and the procedure, and encompassing different organizational options, attempting to individualize it based on specific factors of the patient and the procedure, and encompassing the different organizational options for pain control. The document updates concepts and minimum requirements necessary for optimal postoperative analgesia, a multidisciplinary approach and the management of Acute Postoperative Pain. Strategic lines and different management models are defined. A general perioperative action plan is established based on collaboration with the surgical departments involved, on the joint review of the evidence and on preparation of protocols by the procedure. Finally, a follow-up plan and a series of minimum indicators necessary for quality control of postoperative pain are presented.

Effect of use of NSAIDs or steroids during the acute phase of pain on the incidence of chronic pain: a systematic review and meta-analysis of randomised trials

BACKGROUND

This study is the first to summarize the evidence on how the use of anti-inflammatory drugs during acute pain has an impact on the development of chronic pain.

METHODS

Randomized controlled trials retrieved from nine databases included anti-inflammatory drugs (NSAIDs or steroids) versus non-anti-inflammatory drugs in patients with acute pain and reported the incidence of chronic pain. No specified date, age, sex, or language restrictions. Subgroup analyses were performed according to pain classification, follow-up time, and medication. The GRADE method was used to evaluate quality of evidence.

RESULTS

A total of 29 trials (5220 patients) were included. Steroids or NSAIDs did not reduce the incidence of chronic nociceptive pain. Steroid use in acute phase significantly reduced the incidence of chronic neuropathic pain. In subgroup analysis, benefits were observed for methylprednisolone and dexamethasone, with some adverse effects. Steroids or NSAIDs were statistically significant in reducing pain intensity over 1 year, but the effect size was too small, and whether the long-term effect is clinically relevant needs to be further studied.

CONCLUSION

Quality of the evidence was low to moderate. No drug can be recommended to prevent chronic nociceptive pain. Injections of steroids (methylprednisolone or dexamethasone) during the acute phase reduce the incidence of chronic neuropathic pain, but most included studies also used local anesthetics. The results are indirect and need to be interpreted with caution. The pooled data effect sizes for pain intensity were small, so the clinical relevance was unclear. Study registration PROSPERO (CRD42022367030).

Do baseline patient reported outcome measures predict changes in self-reported function, following a chronic pain rehabilitation programme?

Background

Interdisciplinary pain management programmes, based on cognitive-behavioural principles, aim to improve physical and psychological functioning and enhance self-management in people living with chronic pain. Currently there is insufficient evidence about whether psychological, biological or social factors are predictive of positive outcomes following pain rehabilitation. This study aims to evaluate predictors of change in Brief Pain Inventory - pain interference score (BPI) in a clinical data set to determine whether age, sex and baseline outcome measures are predictive of improvement in pain interference following pain rehabilitation.

Methods

A retrospective, pragmatic observational analysis of routinely collected clinical data in two pain rehabilitation programmes, Balanced Life Programme (BLP) and Get Back Active (GBA) was conducted. Standard regression and hierarchical regression analyses were used to identify predictors of change to assess temporal changes in BPI. Responder analysis was also conducted.

Results

Standard regression analyses of 208 (BLP) and 310 (GBA) patients showed that higher baseline BPI and better physical performance measures predicted better improvement in BPI across both programmes. Hierarchical regression showed that age and sex accounted for 2.7% (BLP) and 0.002% (GBA) of the variance in change in BPI. After controlling for age and sex, the other measures explained an additional 23% (BLP) and 19% (GBA) of the variance, p = < .001 where BPI and physical performance measures were consistently statistically significant predictors, p < .05. Responder analysis also showed that pain interference and physical performance were significantly associated with improvement (p = < .0005).

Conclusions

The combination of high self-reported pain interference and better physical performance measures may be a useful indicator of who would benefit from interdisciplinary rehabilitation. Further validation of the results is required.

The Effects of Anthroposophic Medicine in Chronic Pain Conditions: A Systematic Review

Background: The currently available evidence is unclear in regard to pain-related outcomes of patients with chronic pain conditions who undergo treatment with anthroposophic medicine (AM). Aim: To identify and synthesize the evidence in patients with chronic pain before and after AM therapy. Methods: The following databases and search interfaces were searched on October 21, 2021: Embase (via Embase.com), Medline (via PubMed), and the Cochrane Library. Additional references were identified via bibliographies of included studies. In at least one experimental arm that used anthroposophic therapy to treat chronic pain, AM treatments were required to be documented. Included studies reported on pain severity and physical and emotional functioning. Two authors independently assessed the studies for inclusion criteria, extracted the data, and conducted the quality evaluation of the included studies based on the critical appraisal tools provided by the Joanna Briggs Institute. Results: Seven studies (eight publications) were included in the review, of which were three randomized controlled trials (RCTs), two non-RCTs, and two pretest-post-test studies. A total number of 600 patients participated in the identified experimental studies, of whom all were adults. Three studies included patients with low back pain, one study each assessed patients with fibromyalgia, migraine, dysmenorrhea, and postpolio syndrome, respectively. The identified clinical studies reported considerable reductions in symptoms and effect sizes of pain outcomes after AM therapies being predominantly large, with no notable adverse effects. Conclusion: The findings of this systematic review of studies assessing AM therapies in patients with chronic pain problems revealed that there is a scarcity of evidence currently available, with unclear effects of AM treatments in reducing pain intensity and improving quality of life in the evaluated health conditions. Although most of the studies revealed a favorable benefit on one or more pain-related outcomes, the variability of the research did not allow for generalization across different studies, health conditions, and populations.

Protocol for a Parallel Group Randomized Clinical Trial Comparing a Culturally Adapted Cognitive Behavioral Telerehabilitation Intervention to Usual Physical Therapy for Latino Patients With Chronic Spine Pain

OBJECTIVE

Disparities exist in health care access, diagnosis, and treatment of chronic pain in Latino populations and other minority populations. Cognitive behavioral-based physical therapy (CBPT) interventions have been shown to be effective in predominantly non-Hispanic white populations with chronic spine pain. However, there is a need for culturally adapted CBPT interventions that focus on the conservative management of chronic spine pain. The primary purpose of the study described in this protocol is to test the efficacy of an adapted cognitive behavioral-based hybrid telerehabilitation intervention for Latino patients with chronic spine pain.

METHODS

A single-blind, 2-arm parallel group, superiority randomized clinical trial is planned to compare an adapted CBPT intervention to Usual Care physical therapy. Goal Oriented Activity for Latinos with chronic Spine pain (GOALS/Metas) is an 8-week hybrid telerehabilitation intervention that integrates guideline-based physical therapy and pain management interventions using cognitive behavioral approaches and has been adapted for Latino patients with chronic spine pain. Usual Care physical therapy will be administered based on institutional standards at the referring health center. Outcome measures will be evaluated preintervention and at 1-week, 3-months, and 6-months postintervention. The primary outcome is pain-related disability 1-week postintervention using the Brief Pain Inventory Pain Interference subscale. Secondary outcome measures include behavioral measures of functional activity, social participation, physical activity, and sleep. Determinants of treatment effect, including pain-related psychological measures, posture and movement, self-efficacy, treatment expectancy, and therapeutic alliance, will be included in the secondary moderation and mediation analyses.

IMPACT

This clinical trial will provide information on the extent to which an adapted CBPT hybrid telerehabilitation intervention is effective in reducing pain-related disability for Latino patients with chronic spine pain. This information will be useful for clinicians to integrate in their practice, given the growing population of Latino patients who experience disparities in health care management of chronic pain.

Non-invasive central nervous system assessment of a porcine model of neuropathic pain demonstrates increased latency of somatosensory-evoked potentials

BACKGROUND

The study of chronic pain and its treatments requires a robust animal model with objective and quantifiable metrics. Porcine neuropathic pain models have been assessed with peripheral pain recordings and behavioral responses, but thus far central nervous system electrophysiology has not been investigated. This work aimed to record non-invasive, somatosensory-evoked potentials (SEPs) via electroencephalography in order to quantitatively assess chronic neuropathic pain induced in a porcine model.

NEW METHOD

Peripheral neuritis trauma (PNT) was induced unilaterally in the common peroneal nerve of domestic farm pigs, with the contralateral leg serving as the control for each animal. SEPs were generated by stimulation of the peripheral nerves distal to the PNT and were recorded non-invasively using transcranial electroencephalography (EEG). The P30 wave of the SEP was analyzed for latency changes.

RESULTS

P30 SEPs were successfully recorded with non-invasive EEG. PNT resulted in significantly longer P30 SEP latencies (p < 0.01 [n = 8]) with a median latency increase of 14.3 [IQR 5.0 - 17.5] ms. Histological results confirmed perineural inflammatory response and nerve damage around the PNT nerves.

COMPARISON WITH EXISTING METHOD(S)

Control P30 SEPs were similar in latency and amplitude to those previously recorded invasively in healthy pigs. Non-invasive recordings have numerous advantages over invasive measures.

CONCLUSIONS

P30 SEP latency can serve as a quantifiable neurological measure that reflects central nervous system processing in a porcine model of chronic pain. Advancing the development of a porcine chronic pain model will facilitate the translation of experimental therapies into human clinical trials.

Perceived Effectiveness of Medical Cannabis Among Adults with Chronic Pain: Findings from Interview Data in a Three-Month Pilot Study

Objectives

Patient-reported outcomes are critical to evaluate the effectiveness of medical cannabis as an alternative treatment for chronic pain. This study examined the perceived effectiveness of medical cannabis for chronic pain management among middle-aged and older adults newly initiating medical cannabis.

Methods

Interview data from participants in a three-month pilot study were analyzed to assess the perceived effectiveness of medical cannabis on chronic pain and related outcomes. The interview was conducted after approximately one month of usage and responses were analyzed using the RADaR (Rigorous and Accelerated Data Reduction) technique.

Results

51 adults initiating medical cannabis for chronic pain were interviewed (24 women, 27 men, mean age 54.4, SD = 12.0), with the majority (n=41) identifying as Non-Hispanic White followed by Non-Hispanic Black (n=7), Multi-racial (2), Hispanic White (1). Most study participants (62.7%) reported MC being overall effective. Common benefits included reduced pain intensity, anxiety, and dependency on pain and psychiatric medications. Improvements in physical functioning, sleep quality, and mood were reported. Common challenges included difficulty finding a suitable product or dose, experiencing side effects such as 'undesired high', 'stomach issues', and a limited 'threshold of pain' treatable by the product.

Discussion

Findings suggest most participants perceived medical cannabis to be overall effective for chronic pain management. Participants reported improved physical and mental functioning and reduced use of pain and psychiatric medications. Future research systematically assessing side effects, dosage and mode of consumption is needed to further evaluate the outcomes among adults initiating medical cannabis.

Discordance of global assessment between the patients and physicians predicts 9-year pain-related outcomes in rheumatoid arthritis patients

Introduction

Perspectives regarding the disease state often differ between patients with rheumatoid arthritis (RA) and physicians. The aim of the present longitudinal cohort study was to investigate the impact of the discordance in global assessments between patients and physicians on 9-year pain-related outcomes in patients with rheumatoid arthritis.

Method

Sixty-eight consecutive outpatients with rheumatoid arthritis on their first visit to a tertiary center were included. Baseline measurements included demographic data, drugs used, disease activity, and a modified Health Assessment Questionnaire (mHAQ). Discordance in global assessment between patients and physicians at baseline was defined as 10 mm higher in the patient global assessment (PGA) than in the physician global assessment. A 9-year follow-up assessment included pain intensity, the European Quality of Life 5 Dimensions 3 Level (EQ-5D-3L) scale, Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale (HADS), Pain Disability Assessment Scale (PDAS), and Pain Self-Efficacy Questionnaire (PSEQ).

Results

The number of patients with discordance was 26 (38%) in 68 patients. Patients with a 10 mm higher PGA than the physician global assessment at baseline measurements had significantly worse pain intensity, PCS score, PSEQ score, and EQ-5D-3L score measurements at the 9-year follow-up than those with concordance. A higher mHAQ score and 10 mm higher PGA at baseline were significantly independently associated with the EQ-5D-3L scale score and pain intensity at the 9-year follow-up.

Conclusion

This longitudinal cohort study suggested that discordance in global assessment between patients and physicians modestly predicted worse 9-year pain-related outcomes in patients with rheumatoid arthritis.

Effectiveness of spinal manipulation and biopsychosocial self-management compared to medical care for low back pain: a randomized trial study protocol

BACKGROUND

Chronic low back pain (cLBP) is widespread, costly, and burdensome to patients and health systems. Little is known about non-pharmacological treatments for the secondary prevention of cLBP. There is some evidence that treatments addressing psychosocial factors in higher risk patients are more effective than usual care. However, most clinical trials on acute and subacute LBP have evaluated interventions irrespective of prognosis.

METHODS

We have designed a phase 3 randomized trial with a 2 × 2 factorial design. The study is also a Hybrid type 1 trial with focus on intervention effectiveness while simultaneously considering plausible implementation strategies. Adults (n = 1000) with acute/subacute LBP at moderate to high risk of chronicity based on the STarT Back screening tool will be randomized in to 1 of 4 interventions lasting up to 8 weeks: supported self-management (SSM), spinal manipulation therapy (SMT), both SSM and SMT, or medical care. The primary objective is to assess intervention effectiveness; the secondary objective is to assess barriers and facilitators impacting future implementation. Primary effectiveness outcome measures are: (1) average pain intensity over 12 months post-randomization (pain, numerical rating scale); (2) average low back disability over 12 months post-randomization (Roland-Morris Disability Questionnaire); (3) prevention of cLBP that is impactful at 10-12 months follow-up (LBP impact from the PROMIS-29 Profile v2.0). Secondary outcomes include: recovery, PROMIS-29 Profile v2.0 measures to assess pain interference, physical function, anxiety, depression, fatigue, sleep disturbance, and ability to participate in social roles and activities. Other patient-reported measures include LBP frequency, medication use, healthcare utilization, productivity loss, STarT Back screening tool status, patient satisfaction, prevention of chronicity, adverse events, and dissemination measures. Objective measures include the Quebec Task Force Classification, Timed Up & Go Test, the Sit to Stand Test, and the Sock Test assessed by clinicians blinded to the patients' intervention assignment.

DISCUSSION

By targeting those subjects at higher risk this trial aims to fill an important gap in the scientific literature regarding the effectiveness of promising non-pharmacological treatments compared to medical care for the management of patients with an acute episode of LBP and the prevention of progression to a severe chronic back problem.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03581123.

Effectiveness of Spinal Manipulation and Biopsychosocial Self-Management compared to Medical Care for Low Back Pain: A Randomized Trial Study Protocol

Background Chronic low back pain (cLBP) is widespread, costly, and burdensome to patients and health systems. Little is known about non-pharmacological treatments for the secondary prevention of cLBP. There is some evidence that treatments addressing psychosocial factors in higher risk patients are more effective than usual care. However, most clinical trials on acute and subacute LBP have evaluated interventions irrespective of prognosis. Methods We have designed a phase 3 randomized trial with a 2x2 factorial design. The study is also a Hybrid type 1 trial with focus on intervention effectiveness while simultaneously considering plausible implementation strategies. Adults (n = 1000) with acute/subacute LBP at moderate to high risk of chronicity based on the STarT Back screening tool will be randomized in to 1 of 4 interventions lasting up to 8 weeks: supported self-management (SSM), spinal manipulation therapy (SMT), both SSM and SMT, or medical care. The primary objective is to assess intervention effectiveness; the secondary objective is to assess barriers and facilitators impacting future implementation. Primary effectiveness outcome measures are: (1) average pain intensity over 12 months post-randomization (pain, numerical rating scale); (2) average low back disability over 12 months post-randomization (Roland-Morris Disability Questionnaire); (3) prevention of cLBP that is impactful at 10-12 months follow-up (LBP impact from the PROMIS-29 Profile v2.0). Secondary outcomes include: recovery, PROMIS-29 Profile v2.0 measures to assess pain interference, physical function, anxiety, depression, fatigue, sleep disturbance, and ability to participate in social roles and activities. Other patient-reported measures include LBP frequency, medication use, healthcare utilization, productivity loss, STarT Back screening tool status, patient satisfaction, prevention of chronicity, adverse events, and dissemination measures. Objective measures include the Quebec Task Force Classification, Timed Up & Go Test, the Sit to Stand Test, and the Sock Test assessed by clinicians blinded to the patients' intervention assignment. Discussion By targeting those subjects at higher risk this trial aims to fill an important gap in the scientific literature regarding the effectiveness of promising non-pharmacological treatments compared to medical care for the management of patients with an acute episode of LBP and the prevention of progression to a severe chronic back problem. Trial registration: ClinicalTrials.gov Identifier: NCT03581123.

WWOM VII: Effectiveness of systemic pharmacotherapeutic interventions in the management of BMS: A systematic review and meta-analysis

OBJECTIVES

To determine the effectiveness of systemic pharmacotherapeutic interventions compared to placebo in burning mouth syndrome (BMS) randomized controlled trials (RCTs) based on the core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT).

METHODS

A systematic literature review of RCTs, concerning systemic pharmacotherapeutic interventions for BMS, published from January 1994 through October 2019, and meta-analysis was performed.

RESULTS

Fourteen RCTs (n = 734 participants) were included. Of those, nine were eligible for the quantitative assessment due to the availability/homogeneity of data for at least one of the IMMPACT domains. Pain intensity was the only domain reported in all RCTs. Weighted mean changes in pain intensity, based on visual analogue scale (ΔVAS), were reported in three RCTs at 6 ± 2 weeks and only one RCT at 10+ weeks follow-ups. Quantitative assessment, based on ΔVAS, yielded very low evidence for the effectiveness of alpha-lipoic acid and clonazepam, low evidence for effectiveness of trazodone and melatonin, and moderate evidence for herbal compounds.

CONCLUSIONS

Based on the RCTs studied, variable levels of evidence exist that suggest that select pharmacological interventions are associated with improved symptoms. However, the underreporting of IMMPACT domains in BMS RCTs restricts the multidimensional assessment of systemic interventions outcomes. Standardized outcome measures need to be applied to future RCTs to improve understanding of intervention outcomes.

Neurostimulation for Chronic Low Back Pain during Pregnancy: Implications for Child and Mother Safety

Pain therapy for low back pain in pregnancy is a very topical issue. In fact, it is necessary to balance the patient's needs to control pain with the need to manage a pregnancy without negative effects on the fetus. We report a case of a 37-year-old woman with low back pain treated with neurostimulation before pregnancy. She described severe chronic low back pain unresponsive to pharmacologic treatments. We first implanted a subcutaneous stimulator into the patient, and then a definitive stimulator resulting in excellent pain control. The improvement in her quality of life allowed the woman to become pregnant. We decided to stop neurostimulation with the patient during pregnancy. The patient completed her pregnancy without complications and the baby was born healthy. During the pregnancy, the woman took only paracetamol when needed. However, this painful symptomatology, completely anecdotal, is not attributable solely to the previous spine problem but probably also to the changes occurring during pregnancy. At the end of pregnancy, the neurostimulator was reactivated without any discomfort for the patient, who is now pain free. This case report provides a first line of evidence of a possible treatment of low back pain in women intending to become pregnant, with risk-free management for both the patient and the child.

Pain patterns in chronic pancreatitis and chronic primary pain

BACKGROUND

Abdominal pain is the most distressing symptom of chronic pancreatitis (CP), and current treatments show limited benefit. Pain phenotypes may be more useful than diagnostic categories when planning treatments, and the presence or absence of constant pain in CP may be a useful prognostic indicator.

AIMS

This cross-sectional study examined dimensions of pain in CP, compared pain in CP with chronic primary pain (CPP), and assessed whether constant pain in CP is associated with poorer outcomes.

METHODS

Patients with CP (N = 91) and CPP (N = 127) completed the Comprehensive Pancreatitis Assessment Tool. Differences in clinical characteristics and pain dimensions were assessed between a) CP and CPP and b) CP patients with constant versus intermittent pain. Latent class regression analysis was performed (N = 192) to group participants based on pain dimensions and clinical characteristics.

RESULTS

Compared to CPP, CP patients had higher quality of life (p < 0.001), lower pain severity (p < 0.001), and were more likely to use strong opioids (p < 0.001). Within CP, constant pain was associated with a stronger response to pain triggers (p < 0.05), greater pain spread (p < 0.01), greater pain severity, more features of central sensitization, greater pain catastrophising, and lower quality of life compared to intermittent pain (all p values ≤ 0.001). Latent class regression analysis identified three groups, that mapped onto the following patient groups 1) combined CPP and CP-constant, 2) majority CPP, and 3) majority CP-intermittent.

CONCLUSIONS

Within CP, constant pain may represent a pain phenotype that corresponds with poorer outcomes. CP patients with constant pain show similarities to some patients with CPP, potentially indicating shared mechanisms.

Low Intensity Focused Ultrasound Increases Duration of Anti-Nociceptive Responses in Female Common Peroneal Nerve Injury Rats

OBJECTIVE

Chronic pain affects 7%-10% of Americans, occurs more frequently and severely in females, and available treatments have been shown to have less efficacy in female patients. Preclinical models addressing sex-specific treatment differences in the treatment of chronic pain have been limited. Here we examine the sex-specific effects of low intensity focused ultrasound (liFUS) in a modified sciatic nerve injury (SNI) model.

MATERIALS AND METHODS

A modified SNI performed by ligating the common peroneal nerve (CPN) was used to measure sensory, behavioral pain responses, and nerve conduction studies in female and male rats, following liFUS of the L5 dorsal root ganglion.

RESULTS

Using the same dose of liFUS in females and males of the same weight, CPN latency immediately after treatment was increased for 50 min in females compared to 25 min in males (p < 0.001). Improvements in mechanical pain thresholds after liFUS lasted significantly longer in females (seven days; p < 0.05) compared to males (three days; p < 0.05). In females, there was a significant improvement in depression-like behavior as a result of liFUS (N = 5; p < 0.01); however, because males never developed depression-like behavior there was no change after liFUS treatment.

CONCLUSIONS

Neuromodulation with liFUS has a greater effect in female rats on CPN latency, mechanical allodynia duration, and depression-like behavior. In order to customize neuromodulatory techniques for different patient phenotypes, it is essential to understand how they may alter sex-specific pathophysiologies.

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.

Quality of meta-analyses of non-opioid, pharmacological, perioperative interventions for chronic postsurgical pain: a systematic review

Background

In an attempt to aggregate observations from clinical trials, several meta-analyses have been published examining the effectiveness of systemic, non-opioid, pharmacological interventions to reduce the incidence of chronic postsurgical pain.

Objective

To inform the design and reporting of future studies, the purpose of our study was to examine the quality of these meta-analyses.

Evidence review

We conducted an electronic literature search in Embase, MEDLINE, and the Cochrane Database of Systematic Reviews. Published meta-analyses, from the years 2010 to 2020, examining the effect of perioperative, systemic, non-opioid pharmacological treatments on the incidence of chronic postsurgical pain in adult patients were identified. Data extraction focused on methodological details. Meta-analysis quality was assessed using the A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) critical appraisal tool.

Findings

Our search yielded 17 published studies conducting 58 meta-analyses for gabapentinoids (gabapentin and pregabalin), ketamine, lidocaine, non-steroidal anti-inflammatory drugs, and mexiletine. According to AMSTAR 2, 88.2% of studies (or 15/17) were low or critically low in quality. The most common critical element missing was an analysis of publication bias. Trends indicated an improvement in quality over time and association with journal impact factor.

Conclusions

With few individual trials adequately powered to detect treatment effects, meta-analyses play a crucial role in informing the perioperative management of chronic postsurgical pain. In light of this inherent value and despite a number of attempts, high-quality meta-analyses are still needed.

PROSPERO registration number

CRD42021230941.

Successful management of segmental zoster paresis on the upper arm with temporally burst spinal cord stimulation

Segmental zoster paresis (SZP) of the limbs is characterized by a focal, asymmetric neurogenic weakness that may occur in an extremity affected by herpes zoster (HZ). In this case report, we describe the case of a patient with SZP who presented with these problems and responded well to temporary spinal cord stimulation (SCS) and systematic rehabilitation. A 62-year-old female patient was referred for right upper limb pain, weakness, and insomnia due to pain. After completing the 14-day trial stimulation, the pain numerical rating scale of the patient in the right upper extremity decreased from 8/10 to 2/10. The Athens insomnia scale score decreased from 15/24 to 10/24. Furthermore, the grip strength of the right hands increased from 6.7 to 16.8 kg at discharge. We induced temporal SCS and rehabilitation of the right upper limb SZP and successfully reduced the pain. An in-depth understanding of the neurological complications secondary to HZ should be emphasized, with temporal SCS and rehabilitation expected to play a crucial role in the motor recovery of patients with SZP.

Pregabalin vs placebo to prevent chronic pain after whiplash injury in at-risk individuals: results of a feasibility study for a large randomised controlled trial

ABSTRACT

There are few effective treatments for acute whiplash-associated disorders (WADs). Early features of central sensitisation predict poor recovery. The effect of pregabalin on central sensitisation might prevent chronic pain after acute whiplash injury. This double blind, placebo-controlled randomised controlled trial examined feasibility and potential effectiveness of pregabalin compared with placebo for people with acute WAD. Twenty-four participants with acute WAD (<48 hours) and at risk of poor recovery (pain ≥5/10) were recruited from hospital emergency departments in Queensland, Australia, and randomly assigned by concealed allocation to either pregabalin (n = 10) or placebo (n = 14). Pregabalin was commenced at 75 mg bd, titrated to 300 mg bd for 4 weeks, and then weaned over 1 week. Participants were assessed at 5 weeks and 3, 6, and 12 months. Feasibility issues included recruitment difficulties and greater attrition in the placebo group. For the primary clinical outcome of neck pain intensity, attrition at 5 weeks was pregabalin: 10% and placebo: 36% and at 12 months was pregabalin: 10% and placebo: 43%. Pregabalin may be more effective than placebo for the primary clinical outcome of neck pain intensity at 3 months (mean difference: -4.0 [95% confidence interval -6.2 to -1.7]) on an 11-point Numerical Rating Scale. Effects were maintained at 6 months but not 12 months. There were no serious adverse events. Minor adverse events were more common in the pregabalin group. A definitive large randomised controlled trial of pregabalin for acute whiplash injury is warranted. Feasibility issues would need to be addressed with modifications to the protocol.

Wound Infusion of 0.35% Levobupivacaine Reduces Mechanical Secondary Hyperalgesia and Opioid Consumption After Cesarean Delivery. A Prospective, Randomized, Triple-Blind, Placebo-Controlled Trial

BACKGROUND

Some patients still report moderate-to-severe postoperative pain after cesarean delivery. Local anesthetic wound infusion improves acute pain and might act on peripheral and central sensitization mechanisms; however, no studies have proved this hypothesis. We evaluated the potential benefits of continuous wound infusion of levobupivacaine after cesarean delivery on secondary hyperalgesia (primary end point) and primary hyperalgesia, pain relief, persistent pain, and inflammatory and metabolic stress response.

METHODS

Healthy women scheduled for elective cesarean delivery participated in this prospective, randomized, triple-blind, placebo-controlled trial (NCT01458431). All patients received spinal anesthesia with 0.5% hyperbaric bupivacaine with fentanyl and a multiholed wound catheter placed under the fascia. Women were randomized to receive continuous wound infusion (0.35% levobupivacaine 7 mL/h for 48 hours; group L) or an equal volume of saline (group S). Secondary hyperalgesia to punctate mechanical stimuli was evaluated using dynamic tests, and primary hyperalgesia was evaluated using an electronic von Frey anesthesiometer; both were assessed at 24, 48, and 72 hours. The following variables were collected: intensity of postoperative parietal and visceral pain at rest and on movement rated on a visual analog scale >72 hours, time to first bolus of patient-controlled analgesia (PCA), cumulative dose of rescue morphine (PCA) and acetaminophen, ability to sleep and sleep quality, and patient satisfaction. Persistent postoperative pain was evaluated during a telephone interview at 1, 3, 6, and 12 months after surgery. C-reactive protein, acid glycoprotein, preprandial glucose, insulin, cortisol, prolactin, growth hormone, and interleukin-6 were measured before cesarean delivery and at 8, 24, and 48 hours. Adverse events and patient outcomes were recorded.

RESULTS

Seventy women were included. In group L, the area of secondary hyperalgesia was significantly reduced (43.4 [18.5-80] vs 68.4 [39.0-136] cm2 and 45.1 [0.9-89.8] vs 67.3 [31.3-175] cm2 at 24 and 48 hours, respectively; group:time interaction P value < .001), the mechanical pain threshold was significantly higher at 24 hours (633 [441-802] vs 417 [300-572] g.mm-2; P = .001), and morphine consumption was significantly lower at 24 hours (4 [2-11] vs 11[6-23]; P = .003) compared with group S. Levobupivacaine had no effect on persistent postoperative pain at 1, 3, 6, and 12 months. Plasma insulin levels in the immediate postoperative period and at 8, 24, and 48 hours were significantly lower in group L (P < .001). There were no significant differences in other biochemical parameters of inflammatory and endocrine-metabolic response.

CONCLUSIONS

Levobupivacaine wound infusion provides adequate analgesia and might be an effective antihyperalgesic adjunct.

Evaluating the association of TRPA1 gene polymorphisms with pain sensitivity: a protocol for an adaptive recall by genotype study

BACKGROUND

Pain is a complex polygenic trait whose common genetic underpinnings are relatively ill-defined due in part to challenges in measuring pain as a phenotype. Pain sensitivity can be quantified, but this is difficult to perform at the scale required for genome wide association studies (GWAS). Existing GWAS of pain have identified surprisingly few loci involved in nociceptor function which contrasts strongly with rare monogenic pain states. This suggests a lack of resolution with current techniques. We propose an adaptive methodology within a recall-by-genotype (RbG) framework using detailed phenotyping to screen minor alleles in a candidate 'nociceptor' gene in an attempt to estimate their genetic contribution to pain.

METHODS/DESIGN

Participants of the Avon Longitudinal Study of Parents and Children will be recalled on the basis of genotype at five common non-synonomous SNPs in the 'nociceptor' gene transient receptor potential ankylin 1 (TRPA1). Those homozygous for the common alleles at each of the five SNPs will represent a control group. Individuals homozygous for the minor alleles will then be recruited in a series of three sequential test groups. The outcome of a pre-planned early assessment (interim) of the current test group will determine whether to continue recruitment or switch to the next test group. Pain sensitivity will be assessed using quantitative sensory testing (QST) before and after topical application of 10% cinnamaldehyde (a TRPA1 agonist).

DISCUSSION

The design of this adaptive RbG study offers efficiency in the assessment of associations between genetic variation at TRPA1 and detailed pain phenotypes. The possibility to change the test group in response to preliminary data increases the likelihood to observe smaller effect sizes relative to a conventional multi-armed design, as well as reducing futile testing of participants where an effect is unlikely to be observed. This specific adaptive RbG design aims to uncover the influence of common TRPA1 variants on pain sensation but can be applied to any hypothesis-led genotype study where costly and time intensive investigation is required and / or where there is large uncertainty around the expected effect size.

TRIAL REGISTRATION

ISRCTN, ISRCTN16294731. Retrospectively registered 25th November 2021.

Chronic Pain Following Fracture-Related Surgery: Posttraumatic Rather Than Postsurgical Origin Promotes Chronification-A Prospective Observational Study With 1-Year Follow-up

BACKGROUND

Chronic posttraumatic/postsurgical pain (CPSP) is common after traumatic or surgical damage. Exposure to both trauma and surgery, with the potential for repeated bone and nerve damage, may increase the risk of CPSP after fracture-related surgery. But the (long-term) incidences of CPSP and neuropathic CPSP and the ensuing burdens are unknown. Therefore, the patients were prospectively assessed within 1 year, and the patient-specific characteristics were explored.

METHODS

Between 2017 and 2018, 127 patients (age: 52.9 ± 17.1 years, male: 55.1%) with traumatic fractures needing osteosynthesis (extremities: 91.3%) were assessed posttrauma (before surgery), postsurgery at days 1 to 5, 6 weeks, 3 and 12 months. The primary outcomes are as follows: incidence at 3 and 12 months of CPSP (defined as pain intensity on a numerical rating scale [NRS: 0-10] ≥3), secondary exploration: neuropathic CPSP (NRS ≥3 and Douleur Neuropathique 4 interview [DN4i] score ≥3 [Douleur Neuropathique interview: 0-7]); burden: quality of life (QoL, the EuroQOL five dimensions questionnaire [EQ-5D-3L] descriptive system); and inter alia, the number of analgesics (trial registration: DRKS00011601).

RESULTS

The incidence of CPSP was 57.1% (52/91, n/N) at 3 and 42.7% (35/82) at 12 months postsurgery, including neuropathic CPSP 7.7% (4/52) and 17.1% (6/35), respectively. Descriptively, posttraumatic higher pain intensity at rest (difference of 0.9 ± 1.8 NRS) and the need for more frequent analgesics (by 34.3%) were associated with CPSP a year after surgery compared to those without. As soon as week 6, these patients had developed descriptively a 15% more impaired QoL, with 25% more impairment after 1 year. The patients with CPSP presented with at least 1 neuropathic symptom 12 months later in 68.6% (24/35) of cases, mainly with an early posttraumatic occurrence (without fulfilling the definition of neuropathic CPSP).

CONCLUSIONS

After early fracture-related surgery, high incidences of CPSP (43%) were prospectively observed 1 year postsurgery, up to approximately 1 in 5 patients who had neuropathic CPSP. At the same time, CPSP was accompanied with an impacted QoL and analgesic dependence, both indicating clinical relevance. Moreover, the high incidence and the early posttraumatic occurrence of more intense pain suggest that the initial fracture-related trauma, rather than the surgical trauma, may predominantly trigger CPSP at Y1 (1 year). Therefore, these exploratory results set the direction of required future research. A future clinical hypothesis might be: treat first what hurts first.

Characteristics and influence on quality of life of new-onset pain in critical COVID-19 survivors

Background

Pain is a clinical feature of COVID‐19, however, data about persistent pain after hospital discharge, especially among ICU survivors is scarce. The aim of this study was to explore the incidence and characteristics of new‐onset pain and its impact on Health‐Related Quality of Life (HRQoL), and to quantify the presence of mood disorders in critically ill COVID‐19 survivors.

Methods

This is a preliminary report of PAIN‐COVID trial (NCT04394169) presenting a descriptive analysis in critically ill COVID‐19 survivors, following in person interview 1 month after hospital discharge. Pain was assessed using the Brief Pain Inventory, the Douleur Neuropathique 4 questionnaire and the Pain Catastrophizing Scale. HRQoL was evaluated with the EQ 5D/5L, and mood disorders with the Hospital Anxiety and Depression Scale (HADS).

Results

From 27 May to 19 July 2020, 203 patients were consecutively screened for eligibility, and 65 were included in this analysis. Of these, 50.8% patients reported new‐onset pain; 38.5% clinically significant pain (numerical rating score ≥3 for average pain intensity); 16.9% neuropathic pain; 4.6% pain catastrophizing thoughts, 44.6% pain in ≥2 body sites and 7.7% widespread pain. Patients with new‐onset pain had a worse EQ‐VAS and EQ index value (p < 0.001). Pain intensity was negatively correlated to both the former (Spearman ρ: −0.546, p < 0.001) and the latter (Spearman ρ: −0.387, p = 0.001). HADS anxiety and depression values equal or above eight were obtained in 10.8% and 7.7% of patients, respectively.

Conclusion

New‐onset pain in critically ill COVID‐19 survivors is frequent, and it is associated with a lower HRQoL.

Trial registration No.: NCT04394169. Registered 19 May 2020. https://clinicaltrials.gov/ct2/show/NCT04394169.

Significance

A substantial proportion of severe COVID‐19 survivors may develop clinically significant persistent pain, post‐intensive care syndrome and chronic ICU‐related pain. Given the number of infections worldwide and the unprecedented size of the population of critical illness survivors, providing information about the incidence of new‐onset pain, its characteristics, and its influence on the patients’ quality of life might help establish and improve pain management strategies.

Trigeminal neuropathic pain is alleviated by inhibition of Cav3.3 T-type calcium channels in mice

In this brief report, we demonstrate that the Cav3.3 T-type voltage-gated calcium channel subtype is involved in our FRICT-ION model of chronic trigeminal neuropathic pain. We first showed that the Cacna1i gene encoding Cav3.3 is significantly upregulated in whole trigeminal ganglia of FRICT-ION mice compared to controls at week 10 post-injury. We confirmed protein upregulation of Cav3.3 compared to controls using Western blot analysis of whole trigeminal ganglia tissues. Finally, we demonstrated that intraperitoneal injection of a selective TAT-based Cav3.3 blocking peptide in FRICT-ION mice significantly reduces Cav3.3 protein expression at the peak anti-allodynic effect (4 hrs post-injection) of the attenuated neuropathic pain behavior. We also suggest that blockade of Cav3.3 may be more effective in attenuating trigeminal neuropathic pain in female than male FRICT-ION mice. Therefore, blocking or attenuating Cav3.3 function may be an effective strategy for the treatment of trigeminal neuropathic pain.

Effects of Patient and Surgery Characteristics on Persistent Postoperative Pain: A Mediation Analysis

OBJECTIVE

Acute postoperative pain intensity is associated with persistent postsurgical pain (PPP) risk. However, it remains unclear whether acute postoperative pain intensity mediates the relationship between clinical factors and persistent pain.

MATERIALS AND METHODS

Participants from a mixed surgical population completed the Brief Pain Inventory and Pain Catastrophizing Scale before surgery, and the Brief Pain Inventory daily after surgery for 7 days and at 30 and 90 days after surgery. We considered mediation models using the mean of the worst pain intensities collected daily on each of postoperative days (PODs) 1 to 7 against outcomes of worst pain intensity at the surgical site endpoints reflecting PPP (POD 90) and subacute pain (POD 30).

RESULTS

The analyzed cohort included 284 participants for the POD 90 outcome. For every unit increase of maximum acute postoperative pain intensity through PODs 1 to 7, there was a statistically significant increase of mean POD 90 pain intensity by 0.287 after controlling for confounding effects. The effects of female versus male sex (m=0.212, P=0.034), pancreatic/biliary versus colorectal surgery (m=0.459, P=0.012), thoracic cardiovascular versus colorectal surgery (m=0.31, P=0.038), every minute increase of anesthesia time (m=0.001, P=0.038), every unit increase of preoperative average pain score (m=0.012, P=0.015), and every unit increase of catastrophizing (m=0.044, P=0.042) on POD 90 pain intensity were mediated through acute PODs 1 to 7 postoperative pain intensity.

DISCUSSION

Our results suggest the mediating relationship of acute postoperative pain on PPP may be predicated on select patient and surgical factors.

Development of a common peroneal nerve injury model in domestic swine for the study of translational neuropathic pain treatments

OBJECTIVE

To date, muscular and bone pain have been studied in domestic swine models, but the only neuropathic pain model described in swine is a mixed neuritis model. Common peroneal nerve injury (CPNI) neuropathic pain models have been utilized in both mice and rats.

METHODS

The authors developed a swine surgical CPNI model of neuropathic pain. Behavioral outcomes were validated with von Frey filament testing, thermal sensitivity assessments, and social and motor scoring. Demyelination of the nerve was confirmed through standard histological assessment. The contralateral nerve served as the control.

RESULTS

CPNI induced mechanical and thermal allodynia (p < 0.001 [n = 10] and p < 0.05 [n = 4], respectively) and increased pain behavior, i.e., guarding of the painful leg (n = 12). Myelin protein zero (P0) staining revealed demyelination of the ligated nerve upstream of the ligation site.

CONCLUSIONS

In a neuropathic pain model in domestic swine, the authors demonstrated that CPNI induces demyelination of the common peroneal nerve, which the authors hypothesize is responsible for the resulting allodynic pain behavior. As the anatomical features of domestic swine resemble those of humans more closely than previously used rat and mouse models, utilizing this swine model, which is to the authors' knowledge the first of its kind, will aid in the translation of experimental treatments to clinical trials.

PROMIS Neuropathic and Nociceptive Pain Quality in Musculoskeletal Pain Presentations

OBJECTIVE

Musculoskeletal pain is a significant contributor to the global disease burden. Management of musculoskeletal pain where a neuropathic component is present can be challenging. This study evaluated the internal structure of the Patient-Reported Outcome Measures Information System (PROMIS) pain quality scales, explored the prevalence of neuropathic and nociceptive pain, and identified health demographics and behaviors related to musculoskeletal pain presentations.

METHODS

Patients presenting to the Victoria University Osteopathy Clinic (Melbourne, Vic., Australia) were invited to complete a health demographics and behaviors questionnaire, and the PROMIS Neuropathic (NeuroPQ) and Nociceptive (NociPQ) pain quality scales, before their initial consultation. Descriptive, inferential, and correlation statistics were used to evaluate the PROMIS scales, health demographics, and behaviors. Mokken scale analysis was used to evaluate the internal structure and dimensionality of the NeuroPQ and NociPQ scales.

RESULTS

Three hundred eighty-three (N=383) patients completed the measures. Mokken scaling suggested the PROMIS scales demonstrated acceptable internal structure and were unidimensional. Over 22% of patients demonstrated cutoff scores above 50, suggesting a substantive neuropathic pain component to their musculoskeletal presentation. Patients who reported cigarette smoking, not being born in Australia or not speaking English at home, demonstrated higher NeuroPQ scores. Females demonstrated significantly higher NociPQ scores than males. Pain intensity demonstrated small to medium correlations with NeuroPQ and NociPQ scores.

DISCUSSION

This study provides support for the use of the NeuroPQ and NociPQ scales in musculoskeletal pain patients. Associations with health demographics and behaviors were identified, and patients typically experienced a combination of neuropathic and nociceptive pain.

Web- and Mindfulness-Based Intervention to Prevent Chronic Pain After Cardiac Surgery: Protocol for a Pilot Randomized Controlled Trial

BACKGROUND

Cardiac surgery is a frequently performed procedure. However, pain after cardiac surgery may become chronic (lasting >3 months) in adults. Once discharged from the hospital, patients are at greater risk of developing chronic postsurgical pain (CPSP) and of prolonged opioid use, as they need to self-manage their pain. Psychological risk and protective factors such as pain-related catastrophic thoughts and pain acceptance determine their ability to cope and their use of opioids, which is crucial for self-management of pain. Studies on mindfulness-based cognitive therapy (MBCT) have multiplied their potential effects on pain acceptance and catastrophic thoughts. However, web-based MBCT for the prevention of CPSP has not yet been examined.

OBJECTIVE

The aim of this study is to pilot test a 4-week-long web-based MBCT intervention for adults following discharge from the hospital by assessing the acceptability or feasibility of the intervention and examining preliminary effects on pain intensity, pain interference with activities and opioid use, and pain acceptance and catastrophic thoughts in the 6 months following surgery.

METHODS

A double-blinded pilot randomized controlled trial will be used to assess a web-based MBCT intervention. Patients will be selected according to the following criteria: age ≥18 years; first-time elective cardiac surgery via a median sternotomy; worst pain in the past week score ≥4/10; ability to understand and complete questionnaires in English; and ability to use an electronic device such as a smartphone, computer, or tablet. After baseline measures, 32 participants will be randomized into two groups: one receiving both the brief, 4-week-long web-based MBCT intervention and usual care (experimental group) and the other receiving only one standardized, web-based educational session with weekly reminders and usual care (attention control group). Peer-reviewed competitive funding was received from Florida State University's Council on Research & Creativity in January 2021, as well as research ethics approval from Florida State University's institutional review board.

RESULTS

Recruitment began in June 2021. Unfortunately, because of the current COVID-19 pandemic, recruitment is not progressing as expected. Recruitment strategies are constantly monitored and updated according to latest data and restrictions surrounding the pandemic.

CONCLUSIONS

This research is significant because it targets the trajectory of CPSP, a leading cause of disability and opioid misuse. This is the first study to assess MBCT for the prevention of CPSP after cardiac surgery in the recovery phase. This approach is innovative because it promotes self-management of pain through the modulation of individual factors. If successful, the intervention could be expanded to numerous populations at risk of chronic pain.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/30951.

Regional anesthetics versus analgesia for stopping the persistent postsurgical pain: A meta-analysis

INTRODUCTION

Regional anesthesia might moderate the risk of persistent postsurgical pain, but its effect compared to systemic analgesia is still conflicting. This meta-analysis study was performed to assess the relationship between the efficiency of regional anesthesia versus systemic analgesia in reducing pain persisting longer than 3 months after surgery.

METHODS

Through a systematic literature search up to August 2020, 31 studies included 2975 subjects who underwent surgery at baseline and reported a total of 1471 subjects using regional anesthesia and 1319 subjects using conventional anesthesia were found recording relationships between efficiency of regional anesthesia versus systemic analgesia in reducing pain persisting longer than 3 months after surgery. Odds ratio (OR) with 95% confidence intervals (CIs) was calculated between regional anesthesia versus systemic analgesia in reducing pain persisting longer than 3 months after surgery using the dichotomous methods with a random or fixed-effect model.

RESULTS

Number of subjects reporting persistent pain 3 months postsurgery was significantly lower in regional anesthesia compared to systemic analgesia in thoracotomy (OR, 0.44; 95% CI, 0.29-0.65, P < .001); breast surgery (OR, 0.46; 95% CI, 0.29-0.72, P < .001); and cesarean section (OR, 0.44; 95% CI, 0.27-0.72, P < .001).

CONCLUSIONS

Regional anesthesia might have an independent relationship with lower pain persisting longer than 3 months after thoracotomy, breast surgery, and cesarean section. Further studies are required to validate these findings.

Rationale and study design of an early care, therapeutic education, and psychological intervention program for the management of post-intensive care syndrome and chronic pain after COVID-19 infection (PAIN-COVID): study protocol for a randomized controlled trial

BACKGROUND

Critically ill patients with COVID-19 are an especially susceptible population to develop post-intensive care syndrome (PICS) due to acute respiratory distress syndrome (ARDS). Patients can suffer acute severe pain and may have long-term mental, cognitive, and functional health deterioration after discharge. However, few controlled trials are evaluating interventions for the prevention and treatment of PICS. The study hypothesis is that a specific care program based on early therapeutic education and psychological intervention improves the quality of life of patients at risk of developing PICS and chronic pain after COVID-19. The primary objective is to determine whether the program is superior to standard-of-care on health-related quality of life at 6 months after hospital discharge. The secondary objectives are to determine whether the intervention is superior to standard-of-care on health-related quality of life, incidence of chronic pain and degree of functional limitation, incidence of anxiety, depression, and post-traumatic stress syndrome at 3 and 6 months after hospital discharge.

METHODS

The PAINCOVID trial is a unicentric randomized, controlled, patient-blinded superiority trial with two parallel groups. The primary endpoint is the health-related quality of life at 6 months after hospital discharge, and randomization will be performed with a 1:1 allocation ratio. This paper details the methodology and statistical analysis plan of the trial and was submitted before outcome data were available. The estimated sample size is 84 patients, 42 for each arm. Assuming a lost to follow-up rate of 20%, a sample size of 102 patients is necessary (51 for each arm).

DISCUSSION

This is the first randomized clinical trial assessing the effectiveness of an early care therapeutic education, and psychological intervention program for the management of PICS and chronic pain after COVID-19. The intervention will serve as proof of the need to implement early care programs at an early stage, having an incalculable impact given the current scenario of the pandemic.

TRIAL REGISTRATION

This study is being conducted in accordance with the tenets of the Helsinki Declaration and has been approved by the authors' institutional review board Comité Ético de Investigación Clínica del Hospital Clínic de Barcelona (approval number: HCB/2020/0549) and was registered on May 9, 2020, at clinicaltrials.gov ( NCT04394169 ).

Do quality of life, anxiety, depression and acceptance improve after interdisciplinary pain rehabilitation? A multicentre matched control study of acceptance and commitment therapy-based versus cognitive-behavioural therapy-based programmes

OBJECTIVE

Interdisciplinary pain rehabilitation (IPR) usually employs a cognitive-behavioural therapeutic (CBT) approach. However, there is growing support for chronic pain treatments based on acceptance and commitment therapy (ACT). Most studies of ACT and CBT for chronic pain have evaluated their effects after psychological interventions, not after IPR. We compared the results of an ACT-based IPR programme with two CBT-based IPR programmes.

METHODS

We used a retrospective multicentre pretest-posttest design with matched patient groups at three centres. Data were collected from the Swedish Quality Registry for Pain Rehabilitation before and after IPR participation. Participants completed the EQ-5D health-related quality of life questionnaire, the Chronic Pain Acceptance Questionnaire, (CPAQ) and the Hospital Anxiety and Depression Scale (HADS). Analyses were performed to compare the effects of the different interventions.

RESULTS

Neither EQ-5D nor HADS depression scores were affected by the psychological approach used. The score changes on both CPAQ subscales (activity engagement and pain willingness) indicated significant improvements between admission and discharge at all centres.

CONCLUSIONS

These findings indicate the effectiveness of using psychological approaches to manage chronic pain. Both CBT and ACT had a beneficial effect on most of the assessed health-related parameters.

Pharmacotherapy for the Prevention of Chronic Pain after Surgery in Adults: An Updated Systematic Review and Meta-analysis

BACKGROUND

Chronic postsurgical pain can severely impair patient health and quality of life. This systematic review update evaluated the effectiveness of systemic drugs to prevent chronic postsurgical pain.

METHODS

The authors included double-blind, placebo-controlled, randomized controlled trials including adults that evaluated perioperative systemic drugs. Studies that evaluated same drug(s) administered similarly were pooled. The primary outcome was the proportion reporting any pain at 3 or more months postsurgery.

RESULTS

The authors identified 70 new studies and 40 from 2013. Most evaluated ketamine, pregabalin, gabapentin, IV lidocaine, nonsteroidal anti-inflammatory drugs, and corticosteroids. Some meta-analyses showed statistically significant-but of unclear clinical relevance-reductions in chronic postsurgical pain prevalence after treatment with pregabalin, IV lidocaine, and nonsteroidal anti-inflammatory drugs. Meta-analyses with more than three studies and more than 500 participants showed no effect of ketamine on prevalence of any pain at 6 months when administered for 24 h or less (risk ratio, 0.62 [95% CI, 0.36 to 1.07]; prevalence, 0 to 88% ketamine; 0 to 94% placebo) or more than 24 h (risk ratio, 0.91 [95% CI, 0.74 to 1.12]; 6 to 71% ketamine; 5 to 78% placebo), no effect of pregabalin on prevalence of any pain at 3 months (risk ratio, 0.88 [95% CI, 0.70 to 1.10]; 4 to 88% pregabalin; 3 to 80% placebo) or 6 months (risk ratio, 0.78 [95% CI, 0.47 to 1.28]; 6 to 68% pregabalin; 4 to 69% placebo) when administered more than 24 h, and an effect of pregabalin on prevalence of moderate/severe pain at 3 months when administered more than 24 h (risk ratio, 0.47 [95% CI, 0.33 to 0.68]; 0 to 20% pregabalin; 4 to 34% placebo). However, the results should be interpreted with caution given small study sizes, variable surgical types, dosages, timing and method of outcome measurements in relation to the acute pain trajectory in question, and preoperative pain status.

CONCLUSIONS

Despite agreement that chronic postsurgical pain is an important topic, extremely little progress has been made since 2013, likely due to study designs being insufficient to address the complexities of this multifactorial problem.

EDITOR’S PERSPECTIVE

Effects of behavioural exercise therapy on the effectiveness of multidisciplinary rehabilitation for chronic non-specific low back pain: a randomised controlled trial

BACKGROUND

The long-term effects of behavioural medical rehabilitation (BMR), as a type of multidisciplinary rehabilitation, in the treatment of chronic non-specific low back pain (CLBP) have been shown. However, the specific effects of behavioural exercise therapy (BET) compared to standard exercise therapy (SET) within BMR are not well understood. The aim of the study was to assess the effectiveness of BMR + BET compared to BMR + SET in individuals with CLBP in a two-armed, pre-registered, multicentre, parallel, randomised controlled trial (RCT).

METHODS

A total of 351 adults with CLBP in two rehabilitation centres were online randomised based on an 'urn randomisation' algorithm to either BMR + SET (n = 175) or BMR + BET (n = 176). Participants in both study groups were non-blinded and received BMR, consisting of an multidisciplinary admission, a psychosocial assessment, multidisciplinary case management, psychological treatment, health education and social counselling. The intervention group (BMR + BET) received a manualised, biopsychosocial BET within BMR. The aim of BET was to develop self-management strategies in coping with CLBP. The control group (BMR + SET) received biomedical SET within BMR with the aim to improve mainly physical fitness. Therapists in both study groups were not blinded. The BMR lasted on average 27 days, and both exercise programmes had a mean duration of 26 h. The primary outcome was functional ability at 12 months. Secondary outcomes were e.g. pain, avoidance-endurance, pain management and physical activity. The analysis was by intention-to-treat, blinded to the study group, and used a linear mixed model.

RESULTS

There were no between-group differences observed in function at the end of the BMR (mean difference, 0.08; 95% CI - 2.82 to 2.99; p = 0.955), at 6 months (mean difference, - 1.80; 95% CI; - 5.57 to 1.97; p = 0.349) and at 12 months (mean difference, - 1.33; 95% CI - 5.57 to 2.92; p = 0.540). Both study groups improved in the primary outcome and most secondary outcomes at 12 months with small to medium effect sizes.

CONCLUSION

BMR + BET was not more effective in improving function and other secondary outcomes in individuals with CLBP compared to BMR + SET.

TRIAL REGISTRATION

Current controlled trials NCT01666639 , 16/08/2012.

Effect of Local Anesthetics on Postoperative Pain in Patients Undergoing Gynecologic Laparoscopy: A Systematic Review and Meta-analysis of Randomized Trials

OBJECTIVE

Pain remains a common complication after gynecologic laparoscopy. Use of local anesthesia may be beneficial in reducing postoperative pain. We performed a systematic review and meta-analysis to assess whether local anesthetic decreases postoperative pain after laparoscopic gynecologic procedures.

DATA SOURCES

We searched Cumulative Index to Nursing and Allied Health Literature, Embase, and Medline from inception to November 2020 using Medical Subject Headings and free text combinations.

METHODS OF TRIAL SELECTION

We included randomized controlled trials of patients undergoing gynecologic laparoscopy receiving port site subcutaneous, subfascial, or intraperitoneal local anesthetic compared with placebo or no intervention. We included 20 trials (1861 participants) with size varying between 28 and 164 participants.

TABULATIONS, INTEGRATION, AND RESULTS

Meta-analysis was performed with RevMan 5.3 (Cochrane Collaboration, London, United Kingdom), with standard mean differences (SMDs) and random-effects model. Port site infiltration reduces postoperative pain at 4 hours (SMD -0.25; 95% confidence interval [CI], -0.44 to -0.06; 4 trials; 545 participants) and 6 hours (SMD -0.44; 95% CI, -0.82 to -0.06; 4 trials; 455 participants) after surgery. The administration of intraperitoneal local anesthetics reduces pain at 6 hours (-1.42; 95% CI, -3.22 to -0.30; 4 trials; 277 participants) after surgery.

CONCLUSIONS

The use of port site and intraperitoneal local anesthetic decreases immediate postoperative pain in patients undergoing gynecologic laparoscopy, although its impact on analgesia requirements is unclear. Routine usage of local anesthetics should be considered for people undergoing gynecologic laparoscopy.

Weather sensitivity associated with quality of life in patients with fibromyalgia

Background

Fibromyalgia is characterized by chronic widespread pain, and more than half of patients with fibromyalgia report that weather-related variables aggravate their symptoms. However, the differences in actual symptoms have not been measured between those with and without weather sensitivity. The present study aimed to investigate whether weather sensitivity associated with the minimal clinically important difference values of quality of life in patients with fibromyalgia, between those with and without weather sensitivity.

Methods

Sixty-four consecutive outpatients with fibromyalgia on their first visit to our tertiary center were included. Weather sensitivity was measured using self-perceived symptoms. Pain intensity was measured using the 0–10 Numerical Rating Scale (NRS). Quality of life was measured using the Euro Quality of life-5 Dimensions-3 level (EQ-5D-3L) scale. The variables were subjected to univariable and multivariable analysis using the EQ-5D-3L scale.

Results

The mean age of the patients was 50 years. Forty-eight patients (75%) were women. The mean EQ-5D-3L score was 0.55. Thirty-seven patients (58%) reported weather sensitivity. In univariable analysis, the welfare recipient, weather sensitivity, and NRS values were associated with EQ-5D-3L scale scores. In multivariable analysis, NRS value and weather sensitivity were independently associated with EQ-5D-3L scale scores. The NRS and EQ-5D-3L scale scores were significantly worse in those with weather sensitivity than those without weather sensitivity. The difference in NRS values was less than 1.5 points between groups. The differences in EQ-5D-3L scale scores were 0.16 points between groups.

Conclusions

Weather sensitivity was significantly associated with quality of life in patients with fibromyalgia. There was an association with weather sensitivity and the minimal clinically important difference values of quality of life in patients with fibromyalgia. The presence of weather sensitivity could have a key role in the quality of life in patients with fibromyalgia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-021-00185-4.

The Effect of Psychological Interventions on the Prevention of Chronic Pain in Adults: A Systematic Review and Meta-analysis

OBJECTIVE

Up to 50% of patients develop high-impact chronic pain after an acute care experience and many psychological variables have been identified in this process. We conducted a systematic review and meta-analysis of randomized controlled trials to assess the effect of psychological interventions within 3 months after pain onset.

METHODS

We searched databases for articles published from databases inceptions until July 2019. We used standardized mean differences with 95% confidence intervals to assess treatment effect.

RESULTS

In all, 18 trials were found eligible; 11 of which were included in the meta-analyses. Trials were mainly performed in back pain patients in the middle to late adulthood. Regarding pain intensity, the effect of psychological interventions compared with standard treatments was nonsignificant at 3, 6, and 12 months. We found a moderate significant effect size in favor of psychological interventions compared with standard treatments with regard to disability at 12 months and a small significant effect with regard to coping with pain at 3 months when compared with information alone. Most of meta-analysis findings were associated with a low level of evidence.

DISCUSSION

This systematic review and meta-analysis showed no significant effect of psychological interventions on pain intensity. A positive and significant trend related to these interventions was shown on disability and coping with pain, when compared with standard treatment and information, respectively. However, these findings must be interpreted with caution considering the limited sample of trials. More rigorous randomized controlled trials performed in patients with a high-risk psychological profile are required to elucidate the efficacy of psychological interventions in preventing chronic pain.

Effects of resveratrol in the signaling of neuropathic pain involving P2X3 in the dorsal root ganglion of rats

Neuropathic pain is a major public health problem because it has a considerable impact on life quality of patients. Neuropathic pain caused by a lesion or disease of the somatosensory nervous system, which causes unpleasant and abnormal sensation (dysesthesia), an increased response to painful stimuli (hyperalgesia), and pain in response to a stimulus that does not normally provoke pain (allodynia). P2X receptors from dorsal root ganglion (DRG) play a crucial role in facilitating pain transmission at peripheral and spinal sites. Resveratrol (Res) has neuroprotective effects and improves the pathological and behavioral outcomes of various types of nerve injury. The present study examined the effects of Res on neuropathic pain. Neuropathic pain animal model was created by partial sciatic nerve ligation (pSNL) surgery. We found that consecutive intraperitoneal administration of Res for 21 days reduced the mechanical and thermal nociceptive responses induced by pSNL in a dose-dependent manner. Moreover, Res administration reversed P2X3 expression and phosphorylation of ERK in DRG neurons after peripheral nerve injury. Our results suggested that Res may ameliorate neuropathic pain by suppressing P2X3 up-regulation and ERK phosphorylation in DRG of neuropathic pain rats. Therefore, we concluded that Res has a significant analgesic effect on alleviating neuropathic pain, and thus may serve as a therapeutic approach for neuropathic pain.

A pilot multicentre randomised controlled trial of lidocaine infusion in women undergoing breast cancer surgery

Chronic postoperative pain is common after breast cancer surgery. Peri-operative lidocaine infusion may prevent the development of chronic postoperative pain, but a large-scale trial is required to test this hypothesis. It is unclear whether a pragmatic, multicentre trial design that is consistent with expert guidance, addresses the limitations of previous studies, and overcomes existing translational barriers is safe, effective and feasible. We conducted a double-blind, randomised controlled pilot study in 150 patients undergoing breast cancer surgery across three hospitals in Western Australia. Patients received lidocaine, or equivalent volumes of saline, as an intravenous bolus (1.5 mg.kg^-1 ) and infusion (2 mg.kg^-1 .h^-1 ) intra-operatively, and a subcutaneous infusion (1.33 mg.kg^-1 .h^-1 ) postoperatively for up to 12 h on a standard surgical ward, with novel safety monitoring tools in place. The co-primary outcomes were: in-hospital safety events; serum levels of lidocaine during intravenous and subcutaneous infusion; and annualised enrolment rates per site with long-term data capture. In-hospital safety events were rare, and similar in the placebo and lidocaine arms (3% vs. 1%). Median (IQR [range]) serum lidocaine levels during intravenous (2.16 (1.74-2.83 [1.12-6.06]) µg.ml^-1 , n = 41) and subcutaneous (1.52 (1.28-1.83 [0.64-2.85]) µg.ml^-1 , n = 48) infusion were comparable with previous trials reporting improved pain outcomes. Annualised enrolment approximated 50 patients per site per year, with high levels of protocol adherence and ≥ 99% capture of outcomes at 3 and 6 months. The adjusted odds ratio (95%CI) for postoperative pain at 6 months in the lidocaine arm was 0.790 (0.370-1.684). We conclude that this trial, as designed, is safe, effective and feasible in patients undergoing breast cancer surgery, and a larger-scale trial is planned.

Should we prescribe anticonvulsants for acute herpes zoster neuralgia and to prevent postherpetic neuralgia?: A protocol for meta-analysis and benefit-risk assessment

BACKGROUND

Herpes zoster-associated pain [i.e., acute herpes zoster neuralgia (AHN) and postherpetic neuralgia (PHN)] has the potential to cause significant patients' burden and heath resource expenditure. PHN is refractory to the existing treatments, and the consensus is preventing the transition of AHN to PHN is better than treating PHN. Anticonvulsants (e.g., gabapentin, pregabalin) have been recommended as one of the first-line therapies for PHN. In practice, anticonvulsants have also decreased the severity and duration of AHN and reduced the incidence of PHN. Nevertheless, its clinical application to AHN is hampered by inadequate evidence for its efficacy and safety. We performed this protocol for a systematic review to explore the efficacy and safety of anticonvulsants for AHN. Besides, a benefit-risk assessment of anticonvulsants for AHN would be performed to estimate the extent to which these drugs could relieve symptoms and whether the benefits outweigh harms.

METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) was used to prepare our protocol and the results will be reported according to the PRISMA. We will search the China National Knowledge Infrastructure (CNKI), Chinese VIP Information (VIP), Cochrane Library, Embase, and PubMed databases, from inception to August 2019. Furthermore, Clinicaltrials (http://www.clinicaltrials.com) and Chinese Clinical Trial Registry (http://www.chictr.org.cn/abouten.aspx) will also be searched for relevant studies. Selection of eligible articles and data extraction will be independently performed by reviewers. We will record the characteristic information, pain outcomes, incidence of PHN and adverse effects. Data synthesis and other statistical analyses will be conducted using Review Manager Software 5.3 and STATA13.0. Furthermore, risk of bias assessment, meta-regression and subgroup analyses, publication bias assessment, grading of evidence will be performed for included studies.

ETHICS AND DISSEMINATION

As this systematic review will be performed based on published data, no ethical approval is needed. The findings will be submitted in peer-reviewed journals for publication.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019133449.

[Prevention of chronic pain in the German healthcare system : Current state and perspective]

The current healthcare provision in Germany is established, in particular, for the diagnostics and treatment of chronic pain conditions; however, the current aim is to initiate the diagnostic and therapeutic approaches oriented towards the biopsychosocial pain model in the early stages of pain, i.e. before the onset of chronification, for patients with pain and a risk of chronification in order to actively avoid chronification processes. In this context, multiple risk factors play an important role for the diagnostic and therapeutic approaches as well as for the interdisciplinary multimodal pain therapy developed for this purpose. The Global Year of the International Association for the Study of Pain (IASP) 2020 addressed the prevention of (chronic) pain, a welcome opportunity to provide a short review of the evidence for and clinical experiences with timely diagnostic and therapeutic options and to summarize the current framework conditions and scientific recommendations for Germany. At the end of this article the implications for future research are summarized, particularly for the treatment of patients with pain and risk of chronification.

Essential statistical principles of clinical trials of pain treatments

This article presents an overview of fundamental statistical principles of clinical trials of pain treatments. Statistical considerations relevant to phase 2 proof of concept and phase 3 confirmatory randomized trials investigating efficacy and safety are discussed, including (1) research design; (2) endpoints and analyses; (3) sample size determination and statistical power; (4) missing data and trial estimands; (5) data monitoring and interim analyses; and (6) interpretation of results. Although clinical trials of pharmacologic treatments are emphasized, the key issues raised by these trials are also directly applicable to clinical trials of other types of treatments, including biologics, devices, nonpharmacologic therapies (eg, physical therapy and cognitive-behavior therapy), and complementary and integrative health interventions.

The ACTTION Guide to Clinical Trials of Pain Treatments, part II: mitigating bias, maximizing value

Summaries of the articles included in part II of the ACTTION Guide to Clinical Trials of Pain Treatments are followed by brief overviews of methodologic considerations involving precision pain medicine, pragmatic clinical trials, real world evidence, and patient engagement in clinical trials.

Transition from acute to chronic pain: where cells, systems and society meet

Current treatments for chronic pain are often ineffective. At the same as searching for novel therapeutics, there is growing interest in preventing acute pain becoming chronic. While the field is still in its infancy, its knowledge base is increasingly expanding. Certainly, biomedical factors, for example, the type of tissue damage, are important but they are often not modifiable. Psychosocial risk factors (e.g., thoughts and beliefs about pain, mood, social support, workplace problems) are modifiable. There is an increasing body of research that cognitive behavioral therapy can prevent transition. Internet-based delivery of cognitive behavioral therapy improves access. Clinicians need to be aware that they may inadvertently promote pain chronification in their patients by what they say and do.