Evaluation of composite responder outcomes of pain intensity and physical function in neuropathic pain clinical trials: an ACTTION individual patient data analysis

Towards precision medicine in clinical trials for the treatment of urologic chronic pelvic pain syndrome: lessons from the MAPP Research Network

Randomized clinical trials have resulted in few approved therapies for the treatment of interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome, collectively referred to as urologic chronic pelvic pain syndrome. Heterogenous patient populations, mismatches of treatments to patient phenotypes, non-specific outcomes and use of standard study designs not leveraging phenotypic heterogeneity might have contributed to the inability of previous trials to demonstrate existing efficacy. The Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research Network has identified important phenotypic characteristics associated with differential symptom severity and treatment responsiveness. Based on Multidisciplinary Approach to the Study of Chronic Pelvic Pain findings and external research, empirically informed strategies were generated for defining patient populations, specifying treatments and selecting primary outcomes for future randomized clinical trials in urologic chronic pelvic pain syndrome. Explicitly specifying the scope of eligibility criteria across heterogeneous patient subgroups defined by pain widespreadness, the presence of Hunner lesions, the presence of pain with bladder filling or relieved by voiding, the extent of chronic overlapping pain conditions, and pelvic floor tenderness is needed. Therapies should be selected based on the mechanism of action and relevance to the mechanism of pain and dominant symptomology that the patient experiences. Evidence suggests that pain and urinary symptoms should be evaluated separately. Promising trial designs for identifying effective therapies in this heterogeneous patient population include sequential multiple assignment randomized trials and adaptive designs.

Sensitized-points acupuncture versus routine integrative acupuncture for chronic low back pain: A randomized-controlled feasibility study

BACKGROUND

Chronic low back pain (cLBP) is a global health complaint. Acupuncture is an effective therapy for cLBP; however, evidence for an optimal acupuncture practice scheme is limited.

OBJECTIVE

This study aimed to determine the feasibility of conducting a randomized controlled trial (RCT) to assess the effectiveness of two acupuncture regimes (sensitized-points acupuncture and routine integrative acupuncture package) for cLBP.

METHODS

This was a two-arm, assessor-blind, randomized-controlled feasibility study. Thirty adult participants with cLBP were randomly assigned into two groups. Each group received 8 sessions of either sensitized-points acupuncture or routine integrative acupuncture package, respectively. Treatments were conducted twice per week. Outcomes were assessed at baseline (week 0), on a weekly basis for four weeks (week 1, 2, 3, 4), and follow-up (week 12). Student's t-tests, Mann-Whitney U tests, Fisher's exact tests, descriptive analyses, and power analyses were used for statistics.

RESULTS

Participants were recruited over 10 weeks with a recruitment rate of 12 participants per month. The treatment plan in both groups was well accepted and tolerated. Besides, the study was characterized by low adverse event rates (8.0% in Group A, 11.7% in Group B), high completion of the outcome measures (97.8% in Group A, 94.3% in Group B), and high participant retention rate (100% in Group A, 93.8% in Group B). Furthermore, preliminary analyses showed that both regimes of acupuncture were potentially efficacious and safe.

CONCLUSIONS

Conducting a fully powered RCT to evaluate efficacy and safety of two acupuncture regimes in the management of cLBP is feasible.

Real-world evidence of durable multi-dimensional improvement after 60-day peripheral nerve stimulation treatment used for shoulder pain

Aim: This real-world analysis aims to quantify improvements in multiple health domains in patients who received 60-day peripheral nerve stimulation (PNS) for shoulder pain.Materials & methods: Patients reported percent pain relief and Patient Global Impression of Change in quality of life, physical function and sleep at the end of treatment (EOT), 3 months, and 6 months.Results: Of 768 patients, 80.7% were responders in at least one domain at EOT. In a subset who were followed up, a cumulative 75% continued to respond in at least one domain through 6 months (85% [n = 140/165] at 3 months and 88% [n = 53/60] at 6 months).Conclusion: 60-day PNS used for shoulder pain produced multi-dimensional improvements across health domains at EOT and through 6 months.

ECAP-controlled closed-loop versus open-loop SCS for the treatment of chronic pain: 36-month results of the EVOKE blinded randomized clinical trial

INTRODUCTION

The evidence for spinal cord stimulation (SCS) has been criticized for the absence of blinded, parallel randomized controlled trials (RCTs) and limited evaluations of the long-term effects of SCS in RCTs. The aim of this study was to determine whether evoked compound action potential (ECAP)-controlled, closed-loop SCS (CL-SCS) is associated with better outcomes when compared with fixed-output, open-loop SCS (OL-SCS) 36 months following implant.

METHODS

The EVOKE study was a multicenter, participant-blinded, investigator-blinded, and outcome assessor-blinded, randomized, controlled, parallel-arm clinical trial that compared ECAP-controlled CL-SCS with fixed-output OL-SCS. Participants with chronic, intractable back and leg pain refractory to conservative therapy were enrolled between January 2017 and February 2018, with follow-up through 36 months. The primary outcome was a reduction of at least 50% in overall back and leg pain. Holistic treatment response, a composite outcome including pain intensity, physical and emotional functioning, sleep, and health-related quality of life, and objective neural activation was also assessed.

RESULTS

At 36 months, more CL-SCS than OL-SCS participants reported ≥50% reduction (CL-SCS=77.6%, OL-SCS=49.3%; difference: 28.4%, 95% CI 12.8% to 43.9%, p<0.001) and ≥80% reduction (CL-SCS=49.3%, OL-SCS=31.3%; difference: 17.9, 95% CI 1.6% to 34.2%, p=0.032) in overall back and leg pain intensity. Clinically meaningful improvements from baseline were observed at 36 months in both CL-SCS and OL-SCS groups in all other patient-reported outcomes with greater levels of improvement with CL-SCS. A greater proportion of patients with CL-SCS were holistic treatment responders at 36-month follow-up (44.8% vs 28.4%), with a greater cumulative responder score for CL-SCS patients. Greater neural activation and accuracy were observed with CL-SCS. There were no differences between CL-SCS and OL-SCS groups in adverse events. No explants due to loss of efficacy were observed in the CL-SCS group.

CONCLUSION

This long-term evaluation with objective measurement of SCS therapy demonstrated that ECAP-controlled CL-SCS resulted in sustained, durable pain relief and superior holistic treatment response through 36 months. Greater neural activation and increased accuracy of therapy delivery were observed with ECAP-controlled CL-SCS than OL-SCS.

TRIAL REGISTRATION NUMBER

NCT02924129.

Evaluating the balance of benefits and harms in chronic pain clinical trials: prioritizing individual participants over individual outcomes

BACKGROUND

Randomized clinical trials (RCTs) generally assess efficacy and safety separately, with the conclusion of whether a treatment is beneficial based solely on the efficacy endpoint. However, assessing and combining efficacy and safety domains, using a single composite outcome measure, can provide a more comprehensive assessment of the overall effect of a treatment. Furthermore, composite outcomes can incorporate information regarding the relationship between the individual outcomes. In fact, such outcomes have been suggested in the clinical trials literature for at least 15 years.

OBJECTIVES

To (1) identify whether recent primary publications of chronic pain RCTs from major pain journals included a composite outcome measure of benefits and harms and (2) discuss the potential benefits of such outcomes in various stages of treatment development, including as outcome measures in RCTs, and to support decisions of Data and Safety Monitoring Boards and ordering of treatments in the context of treatment guidelines.

EVIDENCE REVIEW

RCTs published in 6 major pain journals published between 2016 and 2021 that investigated interventions for chronic pain were reviewed.

FINDINGS

Of 73 RCTs identified, only 2 included a composite outcome measure of benefits and harms. Both of these articles compared 2 active treatments.

CONCLUSIONS

Composite outcomes of benefits and harms are underutilized in chronic pain RCTs. The advantages and challenges of using such outcomes are discussed.

Durable multimodal and holistic response for physiologic closed-loop spinal cord stimulation supported by objective evidence from the EVOKE double-blind randomized controlled trial

INTRODUCTION

Chronic pain patients may experience impairments in multiple health-related domains. The design and interpretation of clinical trials of chronic pain interventions, however, remains primarily focused on treatment effects on pain intensity. This study investigates a novel, multidimensional holistic treatment response to evoked compound action potential-controlled closed-loop versus open-loop spinal cord stimulation as well as the degree of neural activation that produced that treatment response.

METHODS

Outcome data for pain intensity, physical function, health-related quality of life, sleep quality and emotional function were derived from individual patient level data from the EVOKE multicenter, participant, investigator, and outcome assessor-blinded, parallel-arm randomized controlled trial with 24 month follow-up. Evaluation of holistic treatment response considered whether the baseline score was worse than normative values and whether minimal clinical important differences were reached in each of the domains that were impaired at baseline. A cumulative responder score was calculated to reflect the total minimal clinical important differences accumulated across all domains. Objective neurophysiological data, including spinal cord activation were measured.

RESULTS

Patients were randomized to closed-loop (n=67) or open-loop (n=67). A greater proportion of patients with closed-loop spinal cord stimulation (49.3% vs 26.9%) were holistic responders at 24-month follow-up, with at least one minimal clinical important difference in all impaired domains (absolute risk difference: 22.4%, 95% CI 6.4% to 38.4%, p=0.012). The cumulative responder score was significantly greater for closed-loop patients at all time points and resulted in the achievement of more than three additional minimal clinical important differences at 24-month follow-up (mean difference 3.4, 95% CI 1.3 to 5.5, p=0.002). Neural activation was three times more accurate in closed-loop spinal cord stimulation (p<0.001 at all time points).

CONCLUSION

The results of this study suggest that closed-loop spinal cord stimulation can provide sustained clinically meaningful improvements in multiple domains and provide holistic improvement in the long-term for patients with chronic refractory pain.

TRIAL REGISTRATION NUMBER

NCT02924129.

Evaluation of Analgesic Drug Therapy for Postoperative Pain Management in Cardiovascular Surgery

Background

Cardiovascular surgery is usually associated with higher degree of postoperative pain that influences a patient's physical recovery. Multiple clinical measures have been taken to avoid overuse of opioid agents for postoperative pain management, which led to the development of clinical pathways for analgesic drug treatment using a multimodal approach.

Objective

To evaluate the effectiveness and safety of a multimodal postoperative analgesic drug pathway (ADP) for pain management following cardiovascular surgery.

Methods

This retrospective, controlled, nonrandomized study evaluated a postoperative ADP in patients undergoing cardiovascular surgery in a tertiary general hospital in Qingdao, China. Effectiveness and safety outcomes were compared before and after the implementation of the ADP. Outcome indicators included postoperative pain scores, consumption of opioids in analgesic pumps, and incidence of adverse events.

Results

Patients who underwent cardiovascular surgery from September to November 2021 before the implementation of the ADP (n = 193) and from September to November 2022 after the implementation of the ADP (n = 218) were enrolled. Pain scores were reduced on day 1, 3, and 5 after surgery and the reduction was most significant in mild pain (P < .001). Opioids in analgesic pumps consumption was also significantly reduced and there was decreased incidence of adverse events such as nausea and vomiting (P = .026), respiratory inhibition (P = .027), and dizziness and headache (P = .028) in cardiovascular surgery patients after implementation of the ADP.

Conclusions

Improved effectiveness and safety were observed following the implementation of the ADP. Multimodal analgesic ADP methodology can be effectively used for postoperative pain management in patients undergoing cardiovascular surgery.

Treatment of Refractory Low Back Pain Using Passive Recharge Burst in Patients Without Options for Corrective Surgery: Findings and Results From the DISTINCT Study, a Prospective Randomized Multicenter Controlled Trial

OBJECTIVE

Spinal cord stimulation (SCS) is effective for relieving chronic intractable pain conditions. The Dorsal spInal cord STImulatioN vs mediCal management for the Treatment of low back pain study evaluates the effectiveness of SCS compared with conventional medical management (CMM) in the treatment of chronic low back pain in patients who had not undergone and were not candidates for lumbar spine surgery.

METHODS AND MATERIALS

Patients were randomized to passive recharge burst therapy (n = 162) or CMM (n = 107). They reported severe pain and disability for more than a decade and had failed a multitude of therapies. Common diagnoses included degenerative disc disease, spondylosis, stenosis, and scoliosis-yet not to a degree amenable to surgery. The six-month primary end point compared responder rates, defined by a 50% reduction in pain. Hierarchical analyses of seven secondary end points were performed in the following order: composite responder rate (numerical rating scale [NRS] or Oswestry Disability Index [ODI]), NRS, ODI, Pain Catastrophizing Scale responder rate, Patient Global Impression of Change (PGIC) responder rate, and Patient-Reported Outcome Measure Information System-29 in pain interference and physical function.

RESULTS

Intention-to-treat analysis showed a significant difference in pain responders on NRS between SCS (72.6%) and CMM (7.1%) arms (p < 0.0001). Of note, 85.2% of those who received six months of therapy responded on NRS compared with 6.2% of those with CMM (p < 0.0001). All secondary end points indicated the superiority of burst therapy over CMM. A composite measure on function or pain relief showed 91% of subjects with SCS improved, compared with 16% of subjects with CMM. A substantial improvement of 30 points was observed on ODI compared with a

CONCLUSIONS

This study found substantial improvement at six months in back pain, back pain-related disability, pain-related emotional suffering, PGIC, pain interference, and physical function in a population with severe, debilitating back pain for more than a decade. These improvements were reported in conjunction with reduced opioid use, injection, and ablation therapy.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT04479787.

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Key Words

• composite outcomes
• persistent spinal pain syndrome
• refractory chronic low back pain
• spinal cord stimulation

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MESH Headings

• Humans
• Low Back Pain/therapy
• Low Back Pain/psychology
• Treatment Outcome
• Prospective Studies
• Back Pain
• Spinal Cord Stimulation/methods
• Chronic Pain/diagnosis
• Chronic Pain/therapy

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Grants

• K08 CA228039 NCI NIH HHS

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Affiliation(s)

Timothy Deer The Spine and Nerve Center of the Virginias, Charleston, WV, USA
Christopher Gilligan Brigham & Women's Hospital, Boston, MA, USA
Steven Falowski Center for Interventional Pain & Spine, Lancaster, PA, USA
Mehul Desai International Spine, Pain & Performance Center, Washington, DC, USA
Julie Pilitsis Florida Atlantic University, FL, USA
Jessica Jameson Axis Spine Center, ID, USA
Susan Moeschler Mayo Clinic, Rochester, NY, USA
Robert Heros Spinal Diagnostics, OR, USA
Edward Tavel Clinical Trials of South Carolina, Charleston, SC, USA
Anne Christopher Saint Louis Pain Consultants, Chesterfield, MO, USA
Denis Patterson Nevada Advanced Pain Specialists, Reno, NV, USA
Sayed Wahezi Montefiore Medical Center-Waters Place, New York, NY, USA
Jacqueline Weisbein Napa Valley Orthopedic Medical Group, Napa, CA, USA
Ajay Antony The Orthopaedic Institute, FL, USA
Robert Funk Indiana Spine Group, IN, USA
Mohab Ibrahim Banner University Medical Center Tucson Campus, Tucson, AZ, USA
Chi Lim Carolina Orthopaedic & Neurosurgical Associates, SC, USA
Derron Wilson Goodman Campbell Brain & Spine, IN, USA
Michael Fishell Advanced Pain Care, NV, USA
Keith Scarfo Rhode Island Hospital, Providence, RI, USA
David Dickerson Northshore University HealthSystem, Chicago, IL, USA
Edward Braun Kansas University Medical Center, KS, USA
Patrick Buchanan Spanish Hills Interventional Pain Specialists, Camarillo, CA, USA
Robert M Levy Anesthesia Pain Care Consultants-Tamarac
Nathan Miller Coastal Pain & Spinal Diagnostics Medical Group, Carlsbad, CA, USA
Jonathan Duncan Burkhart Research Institute for Orthopaedics, San Antonio, TX, USA
Jijun Xu The Cleveland Clinic Foundation, OH, USA
Kenneth Candido Chicago Anesthesia Associates, SC, Chicago, IL, USA
Scott Kreiner Barrow Brain & Spine-Ahwatukee, Phoenix, AZ, USA
Marie E Fahey Abbott Labs, Austin, TX, USA
James Yue Connecticut Orthopaedics, CT, USA

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Back Pain Consortium (BACPAC): Protocol and Pilot Study Results for a Randomized Comparative-Effectiveness Trial of Antidepressants, Fear Avoidance Rehabilitation, or the Combination for Chronic Low Back Pain and Comorbid High Negative Affect

OBJECTIVE

Patients with chronic low back pain (CLBP) and comorbid depression or anxiety disorders are highly prevalent. Negative affect (NA) refers to a combination of negative thoughts, emotions, and behaviors. Patients with CLBP with high NA have greater pain, worse treatment outcomes, and greater prescription opioid misuse. We present the protocol for SYNNAPTIC (SYNergizing Negative Affect & Pain Treatment In Chronic pain).

DESIGN

A randomized comparative-effectiveness study of antidepressants, fear-avoidance rehabilitation, or their combination in 300 patients with CLBP with high NA. In the antidepressant- or rehabilitation-only arms, SYNNAPTIC includes an adaptive design of re-randomization after 4 months for nonresponders.

SETTING

A multisite trial conducted in routine pain clinical treatment settings: pain clinics and physical and occupational therapy treatment centers.

METHODS

Inclusion criteria include CLBP with elevated depression and anxiety symptoms. Antidepressant and rehabilitation treatments follow validated and effective protocols for musculoskeletal pain in patients with high NA. Power and sample size are based on superior outcomes of combination therapy with these same treatments in a 71-subject 4-arm pilot randomized controlled trial.

CONCLUSIONS

SYNNAPTIC addresses the lack of evidence-based protocols for the treatment of the vulnerable subgroup of patients with CLBP and high NA. We hypothesize that combination therapy of antidepressants plus fear-avoidance rehabilitation will be more effective than each treatment alone.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT04747314.

Improving Power and Accuracy in Randomized Controlled Trials of Pain Treatments by Accounting for Concurrent Analgesic Use

The 0 to 10 numeric rating scale of pain intensity is a standard outcome in randomized controlled trials (RCTs) of pain treatments. For individuals taking analgesics, there may be a disparity between "observed" pain intensity (pain intensity with concurrent analgesic use) and pain intensity without concurrent analgesic use (what the numeric rating scale would be had analgesics not been taken). Using a contemporary causal inference framework, we compare analytic methods that can potentially account for concurrent analgesic use, first in statistical simulations, and second in analyses of real (non-simulated) data from an RCT of lumbar epidural steroid injections. The default analytic method was ignoring analgesic use, which is the most common approach in pain RCTs. Compared to ignoring analgesic use and other analytic methods, simulations showed that a quantitative pain and analgesia composite outcome based on adding 1.5 points to pain intensity for those who were taking an analgesic (the QPAC1.5) optimized power and minimized bias. Analyses of real RCT data supported the results of the simulations, showing greater power with analysis of the QPAC1.5 as compared to ignoring analgesic use and most other methods examined. We propose alternative methods that should be considered in the analysis of pain RCTs. PERSPECTIVE: This article presents the conceptual framework behind a new quantitative pain and analgesia composite outcome, the QPAC1.5, and the results of statistical simulations and analyses of trial data supporting improvements in power and bias using the QPAC1.5. Methods of this type should be considered in the analysis of pain RCTs.

Optimizing and Accelerating the Development of Precision Pain Treatments for Chronic Pain: IMMPACT Review and Recommendations

Large variability in the individual response to even the most-efficacious pain treatments is observed clinically, which has led to calls for a more personalized, tailored approach to treating patients with pain (ie, "precision pain medicine"). Precision pain medicine, currently an aspirational goal, would consist of empirically based algorithms that determine the optimal treatments, or treatment combinations, for specific patients (ie, targeting the right treatment, in the right dose, to the right patient, at the right time). Answering this question of "what works for whom" will certainly improve the clinical care of patients with pain. It may also support the success of novel drug development in pain, making it easier to identify novel treatments that work for certain patients and more accurately identify the magnitude of the treatment effect for those subgroups. Significant preliminary work has been done in this area, and analgesic trials are beginning to utilize precision pain medicine approaches such as stratified allocation on the basis of prespecified patient phenotypes using assessment methodologies such as quantitative sensory testing. Current major challenges within the field include: 1) identifying optimal measurement approaches to assessing patient characteristics that are most robustly and consistently predictive of inter-patient variation in specific analgesic treatment outcomes, 2) designing clinical trials that can identify treatment-by-phenotype interactions, and 3) selecting the most promising therapeutics to be tested in this way. This review surveys the current state of precision pain medicine, with a focus on drug treatments (which have been most-studied in a precision pain medicine context). It further presents a set of evidence-based recommendations for accelerating the application of precision pain methods in chronic pain research. PERSPECTIVE: Given the considerable variability in treatment outcomes for chronic pain, progress in precision pain treatment is critical for the field. An array of phenotypes and mechanisms contribute to chronic pain; this review summarizes current knowledge regarding which treatments are most effective for patients with specific biopsychosocial characteristics.

Wellness of patients with chronic pain is not only about pain intensity

OBJECTIVE

Attaining good outcomes in the management of chronic pain remains a clinical challenge. This study aimed to investigate the relationships between - and the contribution of - pain and related conditions to the wellness of these patients.

DESIGN

A secondary analysis of database of patients with chronic pain treated with medical cannabis (MC) to carry out a one-year prospective follow-up study was conducted. Questionnaires were completed before (T₀ ), six (T₆ ), and twelve (T₁₂ ) months after MC initiation. Data included patients' demographics and questionnaires related to three latent factors: pain intensity measures, related conditions (catastrophizing, sleep disturbance, anxiety, and depression), and wellness parameters (quality-of-life, disability, subjective-health-state). Weighted average of the observed variables (WOBs) were calculated for each latent factor. Longitudinal structural equation modeling (SEM) and mediation analyses were performed to identify predictors and interrelations between the WOBs, respectively.

RESULTS

Participants included 510 patients. All variables were significantly improved from T₀ to T₆ and T₁₂ . SEM revealed that related conditions, and to a lesser extent pain, predicted wellness at T₀ , T₆ , and T₁₂ (related conditions: β₀  = 0.55, p < 0.001; β₆  = 0.54, p < 0.001; and β₁₂  = 0.51, p < 0.001; pain: β₀  = 0.42, p < 0.001; β₆  = 0.18, p < 0.001; and β₁₂  = 0.25, p < 0.001). Mediation analyses demonstrated that the effect of WOB-related conditions was greater than WOB-pain on wellness.

CONCLUSION

Wellness of patients with chronic pain can be determined not only by pain itself but even more so by the severity of related conditions. Thus, considering a broad spectrum of pain measures and related conditions seems relevant for improving the wellness of patients with chronic pain.

Real-world evidence of sustained improvement following 60-day peripheral nerve stimulation treatment for pain: a cross-sectional follow-up survey

Objective: This study presents real-world data from a cross-sectional follow-up survey of patients who previously received 60-day peripheral nerve stimulation (PNS) treatment for pain. Materials & methods: A survey including validated pain and other related outcome measures was distributed to patients who previously underwent implantation of temporary PNS leads for 60-day PNS treatment. Results: Among survey respondents who were at least 3 months from the start of treatment, most reported sustained clinically significant improvements in pain and/or quality of life, with the length of follow-up at the time of survey completion ranging from 3 to 30 months. Conclusion: These real-world data support recent prospective studies indicating that 60-day percutaneous PNS provides significant and sustained relief across a wide range of pain conditions.

Baseline- and treatment-associated pain in the X:BOT comparative effectiveness study of extended-release naltrexone versus buprenorphine-naloxone for OUD

Chronic pain is highly prevalent among patients with opioid use disorder (OUD). However, little is known about how pharmacological treatments for OUD, for example, extended-release naltrexone (XR-NTX) and buprenorphine-naloxone (BUP-NX), affect pain. To begin addressing this question, we performed a secondary analysis of pain data on a large prospective 24-week, open-label, randomized-controlled comparative effectiveness trial of XR-NTX versus BUP-NX (X:BOT trial). Participants' pain status was measured by the EuroQol (EQ-5D). Based on their responses to the pain question at baseline, participants were dichotomized into "Pain" versus "No Pain" categories. Participant's pain status was evaluated every 4 weeks. A mixed effects longitudinal logistic regression model was fitted to examine the differential effect of XR-NTX versus BUP-NX on pain, modelling pain at all available follow-up assessments, adjusted for age, sex, and baseline pain. A total of 474 individuals who were successfully inducted onto their assigned medications were included in this analysis. Among participants endorsing pain at baseline, substantial reductions in pain were observed over the course of the study in both treatment groups. Howecver reduction in pain was slightly greater in the group treated with XR-NTX than the one treated with BUP-NX (OR = 1.60 [95% CI: 1.07-2.40], P = 0.023). Future research using instruments and design specifically focused on pain could extend the present observations and evaluate their clinical significance.

Clinical Characteristics, Treatment Effectiveness, and Predictors of Response to Pharmacotherapeutic Interventions Among Patients with Herpetic-Related Neuralgia: A Retrospective Analysis

BACKGROUND

The treatment for herpetic-related neuralgia focuses on symptom control by use of antiviral drugs, anticonvulsants, and tricyclic antidepressants. We aimed to explore the clinical characteristics associated with medication responsiveness, and to build a classifier for identification of patients who have risk of inadequate pain management.

METHODS

We recruited herpetic-related neuralgia patients during a 3-year period. Patients were stratified into a medication-resistant pain (MRP) group when the pain decrease in the visual analogue scale (VAS) is < 3 points, and otherwise a medication-sensitive pain (MSP) group. Multivariate logistic regression was performed to determine the factors associated with MRP. We fitted four machine learning (ML) models, namely logistic regression, random forest, supporting vector machines (SVM), and naïve Bayes with clinical characteristics gathered at admission to identify patients with MRP.

RESULTS

A total of 213 patients were recruited, and 132 (61.97%) patients were diagnosed with MRP. Subacute herpes zoster (HZ) (vs. acute, OR 8.95, 95% CI 3.15-29.48, p = 0.0001), severe lesion (vs. mild lesion, OR 3.84, 95% CI 1.44-10.81, p = 0.0084), depressed mood (unit increase OR 1.10, 95% CI 1.00-1.20, p = 0.0447), and hypertension (hypertension, vs. no hypertension, OR 0.36, 95% CI 0.14-0.87, p = 0.0266) were significantly associated with MRP. Among four ML models, SVM had the highest accuracy (0.917) and receiver operating characteristic-area under the curve (0.918) to discriminate MRP from MSP. Phase of disease is the most important feature when fitting ML models.

CONCLUSIONS

Clinical characteristics collected before treatment could be adopted to identify patients with MRP.

Research approaches for evaluating opioid sparing in clinical trials of acute and chronic pain treatments: Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials recommendations

ABSTRACT

Randomized clinical trials have demonstrated the efficacy of opioid analgesics for the treatment of acute and chronic pain conditions, and for some patients, these medications may be the only effective treatment available. Unfortunately, opioid analgesics are also associated with major risks (eg, opioid use disorder) and adverse outcomes (eg, respiratory depression and falls). The risks and adverse outcomes associated with opioid analgesics have prompted efforts to reduce their use in the treatment of both acute and chronic pain. This article presents Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus recommendations for the design of opioid-sparing clinical trials. The recommendations presented in this article are based on the following definition of an opioid-sparing intervention: any intervention that (1) prevents the initiation of treatment with opioid analgesics, (2) decreases the duration of such treatment, (3) reduces the total dosages of opioids that are prescribed for or used by patients, or (4) reduces opioid-related adverse outcomes (without increasing opioid dosages), all without causing an unacceptable increase in pain. These recommendations are based on the results of a background review, presentations and discussions at an IMMPACT consensus meeting, and iterative drafts of this article modified to accommodate input from the co-authors. We discuss opioid sparing definitions, study objectives, outcome measures, the assessment of opioid-related adverse events, incorporation of adequate pain control in trial design, interpretation of research findings, and future research priorities to inform opioid-sparing trial methods. The considerations and recommendations presented in this article are meant to help guide the design, conduct, analysis, and interpretation of future trials.

A Novel Multi-Dimensional Clinical Response Index Dedicated to Improving Global Assessment of Pain in Patients with Persistent Spinal Pain Syndrome after Spinal Surgery, Based on a Real-Life Prospective Multicentric Study (PREDIBACK) and Machine Learning Techniques

The multidimensionality of chronic pain forces us to look beyond isolated assessment such as pain intensity, which does not consider multiple key parameters, particularly in post-operative Persistent Spinal Pain Syndrome (PSPS-T2) patients. Our ambition was to produce a novel Multi-dimensional Clinical Response Index (MCRI), including not only pain intensity but also functional capacity, anxiety-depression, quality of life and quantitative pain mapping, the objective being to achieve instantaneous assessment using machine learning techniques. Two hundred PSPS-T2 patients were enrolled in the real-life observational prospective PREDIBACK study with 12-month follow-up and received various treatments. From a multitude of questionnaires/scores, specific items were combined, as exploratory factor analyses helped to create a single composite MCRI; using pairwise correlations between measurements, it appeared to more accurately represent all pain dimensions than any previous classical score. It represented the best compromise among all existing indexes, showing the highest sensitivity/specificity related to Patient Global Impression of Change (PGIC). Novel composite indexes could help to refine pain assessment by informing the physician's perception of patient condition on the basis of objective and holistic metrics, and also by providing new insights regarding therapy efficacy/patient outcome assessments, before ultimately being adapted to other pathologies.

An implantable restorative-neurostimulator for refractory mechanical chronic low back pain: a randomized sham-controlled clinical trial

ABSTRACT

Chronic low back pain can be caused by impaired control and degeneration of the multifidus muscles and consequent functional instability of the lumbar spine. Available treatment options have limited effectiveness and prognosis is unfavorable. We conducted an international randomized, double-blind, sham-controlled trial at 26 multidisciplinary centers to determine safety and efficacy of an implantable, restorative neurostimulator designed to restore multifidus neuromuscular control and facilitate relief of symptoms (clinicaltrials.gov identifier: NCT02577354). Two hundred four eligible participants with refractory mechanical (musculoskeletal) chronic LBP and a positive prone instability test indicating impaired multifidus control were implanted and randomized to therapeutic (N = 102) or low-level sham (N = 102) stimulation of the medial branch of the dorsal ramus nerve (multifidus nerve supply) for 30 minutes twice daily. The primary endpoint was the comparison of responder proportions (≥30% relief on the LBP visual analogue scale without analgesics increase) at 120 days. After the primary endpoint assessment, participants in the sham-control group switched to therapeutic stimulation and the combined cohort was assessed through 1 year for long-term outcomes and adverse events. The primary endpoint was inconclusive in terms of treatment superiority (57.1% vs 46.6%; difference: 10.4%; 95% confidence interval, -3.3% to 24.1%, P = 0.138). Prespecified secondary outcomes and analyses were consistent with a modest but clinically meaningful treatment benefit at 120 days. Improvements from baseline, which continued to accrue in all outcome measures after conclusion of the double-blind phase, were clinically important at 1 year. The incidence of serious procedure- or device-related adverse events (3.9%) compared favorably with other neuromodulation therapies for chronic pain.

Hierarchical clustering by patient-reported pain distribution alone identifies distinct chronic pain subgroups differing by pain intensity, quality, and clinical outcomes

Background

In clinical practice, the bodily distribution of chronic pain is often used in conjunction with other signs and symptoms to support a diagnosis or treatment plan. For example, the diagnosis of fibromyalgia involves tallying the areas of pain that a patient reports using a drawn body map. It remains unclear whether patterns of pain distribution independently inform aspects of the pain experience and influence patient outcomes. The objective of the current study was to evaluate the clinical relevance of patterns of pain distribution using an algorithmic approach agnostic to diagnosis or patient-reported facets of the pain experience.

Methods and findings

A large cohort of patients (N = 21,658) completed pain body maps and a multi-dimensional pain assessment. Using hierarchical clustering of patients by body map selection alone, nine distinct subgroups emerged with different patterns of body region selection. Clinician review of cluster body maps recapitulated some clinically-relevant patterns of pain distribution, such as low back pain with radiation below the knee and widespread pain, as well as some unique patterns. Demographic and medical characteristics, pain intensity, pain impact, and neuropathic pain quality all varied significantly across cluster subgroups. Multivariate modeling demonstrated that cluster membership independently predicted pain intensity and neuropathic pain quality. In a subset of patients who completed 3-month follow-up questionnaires (N = 7,138), cluster membership independently predicted the likelihood of improvement in pain, physical function, and a positive overall impression of change related to multidisciplinary pain care.

Conclusions

This study reports a novel method of grouping patients by pain distribution using an algorithmic approach. Pain distribution subgroup was significantly associated with differences in pain intensity, impact, and clinically relevant outcomes. In the future, algorithmic clustering by pain distribution may be an important facet in chronic pain biosignatures developed for the personalization of pain management.

Internet Cognitive-Behavioral Therapy for Painful Chronic Pancreatitis: A Pilot Feasibility Randomized Controlled Trial

INTRODUCTION

Severe abdominal pain is a cardinal symptom of chronic pancreatitis (CP) associated with a high economic and societal burden. In other chronic pain conditions, cognitive-behavioral therapy (CBT) has demonstrated efficacy in improving patient outcomes (e.g., pain-related disability and depression). However, CBT has not yet been evaluated in adult patients with painful CP. We aimed to (i) evaluate the feasibility and acceptability of an adapted Internet CBT program for CP and (ii) generate pilot data regarding the effects of treatment on patient pain outcomes.

METHODS

Thirty adults (mean age = 49.8 years, SD = 12.5; 80% women) with suspected or definite CP were randomized to Internet CBT (Pancreatitis Pain Course) versus control. The Pancreatitis Pain Course has 5 CBT lessons (e.g., thought challenging, relaxation, and activity pacing) delivered over 8 weeks. Pain interference, pain intensity, and quality of life were assessed at pretreatment, posttreatment, and the 3-month follow-up. Qualitative interviews were conducted at posttreatment with a subset of participants.

RESULTS

Eighty percent of participants rated the program as highly acceptable; 64.3% completed all 5 lessons. Qualitative data revealed positive perceptions of program features, relevancy, and skills. Patients randomized to Internet CBT demonstrated moderate to large effects in reducing pain intensity and pain interference from baseline to 3 months. The proportion of treatment responders (>30% improvement) was significantly greater in the Internet-CBT group than in the control group (50% vs 13%, Fisher exact t test P = 0.04).

DISCUSSION

In this first trial of CBT pain self-management in CP, feasibility, acceptability, and preliminary efficacy for reducing pain and disability were demonstrated. Future definitive trials of CBT are needed.

Clinical outcome assessment in clinical trials of chronic pain treatments

Clinical outcome assessments (COAs) measure outcomes that are meaningful to patients in clinical trials and are critical for determining whether a treatment is effective. The objectives of this study are to (1) describe the different types of COAs and provide an overview of key considerations for evaluating COAs, (2) review COAs and other outcome measures for chronic pain treatments that are recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) or other expert groups, and (3) review advances in understanding pain-related COAs that are relevant to clinical trials. The authors reviewed relevant articles, chapters, and guidance documents from the European Medicines Agency and U.S. Food and Drug Administration. Since the original core set of outcome measures were recommended by IMMPACT 14 years ago, several new advancements and publications relevant to the measurement or interpretation of COAs for chronic pain trials have emerged, presenting new research opportunities. Despite progress in the quality of measurement of several outcome domains for clinical trials of chronic pain, there remain some measurement challenges that require further methodological investigation.

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.

Evaluation of an effectiveness and safety of the electroacupuncture in the management of intractable neuropathic pain: A prospective, open-labeled, randomized, cross-over clinical trial

BACKGROUND

There is no sufficient evidence on the effectiveness of acupuncture for neuropathic pain. This protocol describes a study that aims to evaluate the effectiveness and safety of electroacupuncture combined with conventional medicine for patients with intractable neuropathic pain, when compared with conventional medicine alone.

METHODS/DESIGN

This study is a prospective, open-labeled, randomized, cross-over clinical trial. A total of 40 patients with neuropathic pain who had a numeric rating scale (NRS) score of over 4 despite receiving conventional treatment for more than 3 months will be enrolled. Participants will receive conventional treatment for neuropathic pain (treatment C) or treatment C combined with 12 additional sessions of electroacupuncture treatment (treatment A) for 6 weeks. Participants will be randomly assigned to 1 of the 2 sequence groups (AC and CA group) with a 1:1 allocation. The differences of responder in the composite efficacy outcomes, which consist of the NRS, Brief Pain Inventory-Short Form (BPI-SF) pain subscale, and global assessment at 6 weeks after randomization will be examined as the primary outcome. Secondary outcomes include differences in the NRS, the Short-Form McGill Pain Questionnaire, BPI-SF, Fatigue Severity Scale, Hospital Anxiety and Depression Scale, Medical Outcomes Study Sleep Scale, global assessment, EQ-5D, and incremental cost-effective ratio at 6 and 15 weeks after randomization. Adverse events, vital signs, and physical examinations will be recorded to evaluate safety.

DISCUSSION

The study protocol for this trial will provide up-to-date evidence on the effectiveness and safety of electroacupuncture for patients with intractable neuropathic pain. The results will be disseminated through a peer-reviewed journal and conference presentations.

TRIAL REGISTRATION

Clinical Research Information Service, ID: KCT0003615. Registered on March 12, 2019. https://cris.nih.go.kr/cris/search/search_result_st01_kren.jsp?seq=13410& ltype=&rtype=.

Minimum important change values for pain and disability: which is the best to identify a meaningful response in patients with chronic nonspecific low back pain?

PURPOSE

To examine the association between different minimum important change (MIC) values for pain and disability and a successful response in global perception of improvement in patients with chronic nonspecific low back pain (CNLBP).

METHODS

A prospective cohort study was conducted. At baseline, all participants completed a sociodemographic and clinical questionnaire, the Numeric Pain Rating Scale and the Quebec Back Pain Disability Scale (QBPDS). After a physiotherapy program, the Global Perceived Effect Scale (GPES) was completed together with pain and disability measures. The association of the different literature MIC values for pain and disability with a successful response on the GPES was analyzed using logistic regression models. The discrimination power, sensitivity, specificity and predictive values were computed.

RESULTS

A total of 183 patients with CNLBP participated in this study. A reduction of 30% on the QBPDS (OR = 7.8; area under the curve = 0.73; sensitivity = 0.72; specificity = 0.76) most accurately identified patients who perceived a global improvement on the GPES. Composite criteria using both pain and disability MIC values presented high odds ratios and specificity values, but failed to identify patients who perceived a meaningful improvement.

CONCLUSION

A 30% reduction on the QBPDS is recommended to identify patients with CNLBP who achieve a clinical improvement with physiotherapy treatment.

Operative Intervention Does Not Change Pain Perception in Patients With Diabetic Foot Ulcers

Researchers investigated pain perception in patients with diabetic foot ulcers (DFUs) by analyzing pre- and postoperative physical function (PF), pain interference (PI), and depression domains of the Patient-Reported Outcome Measurement Information System (PROMIS). They hypothesized that 1) because of painful diabetic peripheral neuropathy (DPN), a majority of patients with DFUs would have high PROMIS PI scores unchanged by operative intervention, and 2) the initially assessed PI, PF, and depression levels would be correlated with final outcomes. Seventy-five percent of patients with DFUs reported pain, most likely because of painful DPN. Those who reported high PI and low PF were likely to report depression. PF, PI, and depression levels were unchanged after operative intervention or healing of DFUs.

Topical Review: Enhancing Understanding of the Clinical Meaningfulness of Outcomes to Assess Treatment Benefit from Psychological Therapies for Children with Chronic Pain

OBJECTIVE

Despite the availability of measures for assessing physical, psychological, and health impact in children with chronic pain, there are not established guidelines for interpretation of children's pain outcomes following psychological treatment. The purpose of this topical review is to discuss clinical significance as a neglected area of consideration in pediatric chronic pain assessment and to make recommendations on how the field can move toward benchmarking on core outcome domains.

METHOD

We review definitions of clinical significance and examples of several methodologies that have been used in other populations or are emerging in pediatric chronic pain including anchor-based methods, distribution-based methods, or multimethod approaches.

RESULTS

Few measures across pediatric chronic pain outcome domains have established clinical significance of scores to interpret meaningful change following treatment limiting the interpretability of findings from clinical trials. In the context of clinical practice, several efforts to examine clinical significance to improve the translation of evidence-based measurement into standard clinical decision-making exist.

CONCLUSIONS

Recommendations are provided to encourage additional validation efforts of outcome measures in pediatric chronic pain and to encourage authors to report clinical significance in clinical trials of psychological interventions for pediatric chronic pain.

Opioid system modulation with buprenorphine/samidorphan combination for major depressive disorder: two randomized controlled studies

The endogenous opioid system is thought to play an important role in the regulation of mood. Buprenorphine/samidorphan (BUP/SAM) combination is an investigational opioid system modulator for adjunctive treatment of major depressive disorder (MDD). To confirm results from early studies, we report the efficacy and safety of BUP/SAM as adjunctive treatment in patients with MDD and an inadequate response to antidepressant therapy (ADT) in FORWARD-4 and FORWARD-5: two phase 3, randomized, double-blind, placebo-controlled studies that utilized the same sequential parallel-comparison design. Efficacy was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS). FORWARD-5 achieved the primary endpoint and demonstrated that adjunctive BUP/SAM 2 mg/2 mg was superior to placebo (average difference change from baseline to week 3 through end of treatment [EOT] in MADRS-6 and -10 versus placebo: -1.5, P = 0.018; -1.9, P = 0.026, respectively). FORWARD-4 did not achieve the primary endpoint (change from baseline in MADRS-10 at week 5 versus placebo: -1.8, P = 0.109), although separate analyses showed significant treatment differences at other timepoints using traditional, regulatory-accepted endpoints such as reduction in MADRS-10 at EOT. The pooled analysis of the two studies demonstrated consistently greater reduction in MADRS-10 scores from baseline for BUP/SAM 2 mg/2 mg versus placebo at multiple timepoints including EOT and average change from baseline to week 3 through EOT (-1.8, P = 0.010; -1.8, P = 0.004, respectively). The overall effect size (Hedges' g) in the pooled analyses for MADRS-10 change from baseline to EOT was 0.22. Overall, BUP/SAM was generally well tolerated, with most adverse events (AEs) being mild or moderate in severity. The most common AEs, occurring in ≥5% of patients in the BUP/SAM 2 mg/2 mg treatment group, which was more frequently than the placebo group, included nausea, constipation, dizziness, vomiting, somnolence, fatigue, and sedation. There was minimal evidence of abuse, and no evidence of dependence or opioid withdrawal by AEs or objective measures. This report describes adjunctive BUP/SAM 2 mg/2 mg combination, a therapy with a novel opioidergic mechanism of action, as a potential new treatment option for patients with MDD who have an inadequate response to currently available ADT.

A national center for persistent severe pain after groin hernia repair: Five-year prospective data

Severe persistent pain after groin hernia repair impairs quality-of-life. Prospective, consecutive cohort study including patients with pain-related impairment of physical and social life. Relevant surgical records were obtained, and examinations were by standardized clinical and neurophysiological tests. Patients demonstrating pain sensitivity to pressure algometry in the operated groin underwent re-surgery, while patients with neuropathic pain received pharmacotherapy. Questionnaires at baseline (Q0) and at the 5-year time point (Q5Y) were used in outcome analyses of pain intensity (numeric rating scale [NRS] 0-10) and pain-related effect on the activity-of-daily-living (Activities Assessment Scale [AAS]). Data are mean (95% CI).Analyses were made in 172/204 (84%) eligible patients. In 54/172 (31%) patients re-surgery (meshectomy/selective neurectomy) was performed, while the remaining 118/172 (69%) patients received pharmacotherapy. In the re-surgery group, activity-related, and average NRS-scores at Q0 were 6.6 (5.6-7.9) and 5.9 (5.6-5.9), respectively. Correspondingly, NRS-scores at Q5Y was 4.1 (3.3-5.1) and 3.1 (2.3-4.0; Q0 vs. Q5Y: P < .0005), respectively. Although both groups experienced a significant improvement in AAS-scores comparing Q0 vs. Q5Y (re-surgery group: 28% (4-43%; P < .0001); pharmacotherapy group: 5% (0-11%; P = .005)) the improvement was significantly larger in the re-surgery group (P = .02).This 5-year cohort study in patients with severe persistent pain after groin hernia repair signals that selection to re-surgery or pharmacotherapy, based on examination of pain sensitivity, is associated with significant improvement in outcome. Analyzing composite endpoints, combining pain and physical function, are novel in exploring interventional effects.ClinicalTrials.gov Identifier NCT03713047.

Composite Pain Biomarker Signatures for Objective Assessment and Effective Treatment

Pain is a subjective sensory experience that can, mostly, be reported but cannot be directly measured or quantified. Nevertheless, a suite of biomarkers related to mechanisms, neural activity, and susceptibility offer the possibility-especially when used in combination-to produce objective pain-related indicators with the specificity and sensitivity required for diagnosis and for evaluation of risk of developing pain and of analgesic efficacy. Such composite biomarkers will also provide improved understanding of pain pathophysiology.