Use of patient-reported global assessment measures in clinical trials of chronic pain treatments: ACTTION systematic review and considerations.

ABSTRACT: Establishing clinically meaningful changes in pain experiences remains important for clinical trials of chronic pain treatments. Regulatory guidance and pain measurement initiatives have recommended including patient-reported global assessment measures (eg, Patient-Global Impression of Change [PGIC]) to aid interpretation of within-patient differences in domain-specific clinical trial outcomes (eg, pain intensity). The objectives of this systematic review were to determine the frequency of global assessment measures inclusion, types of measures, domains assessed, number and types of response options, and how measures were analyzed. Of 4172 abstracts screened across 6 pain specialty journals, we reviewed 96 clinical trials of chronic pain treatments. Fifty-two (54.2%) studies included a global assessment measure. The PGIC was most common (n = 28; 53.8%), with relatively infrequent use of other measures. The majority of studies that used a global assessment measure (n = 31; 59.6%) assessed change or improvement in an unspecified domain. Others assessed overall condition severity (n = 9; 17.3%), satisfaction (n = 8; 15.4%), or overall health status/recovery (n = 5; 9.6%). The number, range, and type of response options were variable and frequently not reported. Response options and reference periods even differed within the PGIC. Global assessment measures were most commonly analyzed as continuous variables (n = 24; 46.2%) or as dichotomous variables with positive categories combined to calculate the proportion of participants with a positive response to treatment (n = 18; 34.6%). This review highlights the substantial work necessary to clarify measurement and use of patient global assessment in chronic pain trials and provides short- and long-term considerations for measure selection, reporting and analysis, and measure development.

Methods for pragmatic randomized clinical trials of pain therapies: IMMPACT statement.

ABSTRACT: Pragmatic, randomized, controlled trials hold the potential to directly inform clinical decision making and health policy regarding the treatment of people experiencing pain. Pragmatic trials are designed to replicate or are embedded within routine clinical care and are increasingly valued to bridge the gap between trial research and clinical practice, especially in multidimensional conditions, such as pain and in nonpharmacological intervention research. To maximize the potential of pragmatic trials in pain research, the careful consideration of each methodological decision is required. Trials aligned with routine practice pose several challenges, such as determining and enrolling appropriate study participants, deciding on the appropriate level of flexibility in treatment delivery, integrating information on concomitant treatments and adherence, and choosing comparator conditions and outcome measures. Ensuring data quality in real-world clinical settings is another challenging goal. Furthermore, current trials in the field would benefit from analysis methods that allow for a differentiated understanding of effects across patient subgroups and improved reporting of methods and context, which is required to assess the generalizability of findings. At the same time, a range of novel methodological approaches provide opportunities for enhanced efficiency and relevance of pragmatic trials to stakeholders and clinical decision making. In this study, best-practice considerations for these and other concerns in pragmatic trials of pain treatments are offered and a number of promising solutions discussed. The basis of these recommendations was an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) meeting organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks.

Pilot trial testing the effects of exercise on chemotherapy-induced peripheral neurotoxicity (CIPN) and the interoceptive brain system.

Purpose: Chemotherapy-induced peripheral neurotoxicity (CIPN) is a prevalent, dose-limiting, tough-to-treat toxicity involving numbness, tingling, and pain in the extremities with enigmatic pathophysiology. This randomized controlled pilot study explored the feasibility and preliminary efficacy of exercise during chemotherapy on CIPN and the role of the interoceptive brain system, which processes bodily sensations. Methods: Nineteen patients (65±11 years old, 52% women; cancer type: breast, gastrointestinal, multiple myeloma) starting neurotoxic chemotherapy were randomized to 12 weeks of exercise (home-based, individually tailored, moderate intensity, progressive walking and resistance training) or active control (nutrition education). At pre-, mid-, and post-intervention, we assessed CIPN symptoms (primary clinical outcome: CIPN-20), CIPN signs (tactile sensitivity using monofilaments), and physical function (leg strength). At pre- and post-intervention, we used task-free ("resting") fMRI to assess functional connectivity in the interoceptive brain system, involving the salience and default mode networks. Results: The study was feasible (74-89% complete data across measures) and acceptable (95% retention). We observed moderate/large beneficial effects of exercise on CIPN symptoms (CIPN-20, 0-100 scale: -7.9±5.7, effect size [ES]=-0.9 at mid-intervention; -4.8±7.3, -ES=0.5 at post-intervention), CIPN signs (ES=-1.0 and -0.1), and physical function (ES=0.4 and 0.3). Patients with worse CIPN after neurotoxic chemotherapy had lower functional connectivity within the default mode network (R2=40-60%) and higher functional connectivity within the salience network (R2=20-40%). Exercise tended to increase hypoconnectivity and decrease hyperconnectivity seen in CIPN (R2 = 12%). Conclusion: Exercise during neurotoxic chemotherapy is feasible and may attenuate CIPN symptoms and signs, perhaps via changes in interoceptive brain circuitry. Future work should test for replication with larger samples. ClinicalTrials.gov identifier NCT03021174.

Patient engagement in designing, conducting, and disseminating clinical pain research: IMMPACT recommended considerations.

ABSTRACT: In the traditional clinical research model, patients are typically involved only as participants. However, there has been a shift in recent years highlighting the value and contributions that patients bring as members of the research team, across the clinical research lifecycle. It is becoming increasingly evident that to develop research that is both meaningful to people who have the targeted condition and is feasible, there are important benefits of involving patients in the planning, conduct, and dissemination of research from its earliest stages. In fact, research funders and regulatory agencies are now explicitly encouraging, and sometimes requiring, that patients are engaged as partners in research. Although this approach has become commonplace in some fields of clinical research, it remains the exception in clinical pain research. As such, the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials convened a meeting with patient partners and international representatives from academia, patient advocacy groups, government regulatory agencies, research funding organizations, academic journals, and the biopharmaceutical industry to develop consensus recommendations for advancing patient engagement in all stages of clinical pain research in an effective and purposeful manner. This article summarizes the results of this meeting and offers considerations for meaningful and authentic engagement of patient partners in clinical pain research, including recommendations for representation, timing, continuous engagement, measurement, reporting, and research dissemination.

Wireless Transcutaneous Electrical Nerve Stimulation (TENS) for Chronic Chemotherapy-Induced Peripheral Neuropathy (CIPN): A Proof-of-Concept Randomized Clinical Trial.

Chemotherapy-induced peripheral neuropathy (CIPN) affects approximately 30 to 60% of people who receive neurotoxic chemotherapy. CIPN is associated with impaired quality of life and function and has few effective treatments. This 6-site, subject and assessor-blinded randomized clinical trial (RCT) was designed to assess 1) preliminary efficacy (ie, alpha pre-specified at .2) of a wearable, app-controlled, transcutaneous electrical nerve stimulation (TENS) device for chronic CIPN and 2) feasibility of conducting a confirmatory trial within the National Cancer Institute Community Oncology Research Program (NCORP) (NCT04367480). The primary outcome was the EORTC-CIPN20. The main secondary outcomes were individual symptoms assessed daily (via 0-10 numeric rating scales). The primary analysis was an analysis of covariance (outcome: EORTC-CIPN20, fixed effect: arm, covariates: baseline EORTC-CIPN20 and site). Secondary analyses used a similar analysis of covariance models (excluding site) for each symptom on subgroups of subjects with ≥4 out of 10 for that symptom at baseline. 142 eligible subjects were randomized and received a device; 130 (91%) completed the study. The difference between groups in the EORCT-CIPN20 at the endpoint (placebo-active) was 1.05 (95% Confidence Interval: -.56, 2.67; P = .199). The difference between groups for the individual symptoms was as follows: hot/burning pain: 1.37 (-.33, 3.08; P = .112), sharp/shooting pain: 1.21 (-.37, 2.79; P = .128), cramping: 1.35 (-.32, 3.02; P = .110), tingling: .23 (-.61, 1.08; P = .587), numbness: .27 (-.51, 1.05; P = .492). An RCT of an app-controlled TENS device for chronic CIPN with excellent retention is feasible in the NCORP. Preliminary efficacy evidence suggests that TENS is promising for pain and cramping from CIPN. A confirmatory RCT of TENS for painful CIPN is highly warranted. PERSPECTIVE: Daily, home-based TENS therapy demonstrates promising efficacy for painful CIPN symptoms in this proof-of-concept randomized clinical trial. Future confirmatory trial is warranted.

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.

Covariate Adjustment in Chronic Pain Trials: An Oft-Missed Opportunity.

Self-reported pain intensity, frequently used as an outcome in randomized clinical trials (RCTs) of chronic pain, is often highly variable and could be associated with multiple baseline factors. Thus, the assay sensitivity of pain trials (ie, the ability of the trial to detect a true treatment effect) could be improved by including prespecified baseline factors in the primary statistical model. The objective of this focus article was to characterize the baseline factors included in statistical analyses of chronic pain RCTs. Seventy-three RCTs published between 2016 and 2021 that investigated interventions for chronic pain were included. The majority of trials identified a single primary analysis (72.6%; n = 53). Of these, 60.4% (n = 32) included one or more covariates in the primary statistical model, most commonly baseline value of the primary outcome, study site, sex, and age. Only one of the trials reported information regarding associations between covariates and outcomes (ie, information that could inform prioritization of covariates for prespecification in future analyses). These findings demonstrate inconsistent use of covariates in the statistical models in chronic pain clinical trials. Prespecified adjustments for baseline covariates that could increase precision and assay sensitivity should be considered in future clinical trials of chronic pain treatments. PERSPECTIVE: This review demonstrates inconsistent inclusion and potential underutilization of covariate adjustment in analyses of chronic pain RCTs. This article highlights areas for possible improvement in design and reporting related to covariate adjustment to improve efficiency in future RCTs.

Research objectives and general considerations for pragmatic clinical trials of pain treatments: IMMPACT statement.

ABSTRACT: Many questions regarding the clinical management of people experiencing pain and related health policy decision-making may best be answered by pragmatic controlled trials. To generate clinically relevant and widely applicable findings, such trials aim to reproduce elements of routine clinical care or are embedded within clinical workflows. In contrast with traditional efficacy trials, pragmatic trials are intended to address a broader set of external validity questions critical for stakeholders (clinicians, healthcare leaders, policymakers, insurers, and patients) in considering the adoption and use of evidence-based treatments in daily clinical care. This article summarizes methodological considerations for pragmatic trials, mainly concerning methods of fundamental importance to the internal validity of trials. The relationship between these methods and common pragmatic trials methods and goals is considered, recognizing that the resulting trial designs are highly dependent on the specific research question under investigation. The basis of this statement was an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) systematic review of methods and a consensus meeting. The meeting was organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership. The consensus process was informed by expert presentations, panel and consensus discussions, and a preparatory systematic review. In the context of pragmatic trials of pain treatments, we present fundamental considerations for the planning phase of pragmatic trials, including the specification of trial objectives, the selection of adequate designs, and methods to enhance internal validity while maintaining the ability to answer pragmatic research questions.

Cannabinoid Therapy: Attitudes and Experiences of People With Chronic Pain.

OBJECTIVE: Clinical trials of cannabinoids for chronic pain have mixed and often inconclusive results. In contrast, many prospective observational studies show the analgesic effects of cannabinoids. This survey study aimed to examine the experiences/attitudes of individuals with chronic pain who are currently taking, have previously taken, or never taken cannabinoids for chronic pain to inform future research. METHODS: This study is based on a cross-sectional, web-based survey of individuals with self-reported chronic pain. Participants were invited to participate through an email that was distributed to the listservs of patient advocacy groups and foundations that engage individuals with chronic pain. RESULTS: Of the 969 respondents, 444 (46%) respondents reported currently taking, 213 (22%) previously taken, and 312 (32%) never taken cannabinoids for pain. Participants reported using cannabinoids to treat a wide variety of chronic pain conditions. Those currently taking cannabinoids (vs previously) more frequently reported: (1) large improvements from cannabinoids in all pain types, including particularly difficult-to-treat chronic overlapping pain conditions (eg, pelvic pain), (2) improvements in comorbid symptoms (eg, sleep), and (3) lower interference from side effects. Those currently taking cannabinoids reported more frequent and satisfactory communication with clinicians regarding cannabinoid use. Those never taken cannabinoids reported a lack of suggestion/approval of a clinician (40%), illegality (25%), and lack of FDA regulation (19%) as reasons for never trying cannabinoids. CONCLUSION: These findings underscore the importance of conducting high-quality clinical trials that include diverse pain populations and clinically relevant outcomes that if successful, could support FDA approval of cannabinoid products. Clinicians could then prescribe and monitor these treatments similarly to other chronic pain medications.

Expectations for Improvement: A Neglected but Potentially Important Covariate or Moderator for Chronic Pain Clinical Trials.

Variability in pain-related outcomes can hamper assay sensitivity of chronic pain clinical trials. Expectations of outcome in such trials may account for some of this variability, and thereby impede development of novel pain treatments. Measurement of participants' expectations prior to initiating study treatment (active or placebo) is infrequent, variable, and often unvalidated. Efforts to optimize and standardize measurement, analysis, and management of expectations are needed. In this Focus Article, we provide an overview of research findings on the relationship between baseline expectations and pain-related outcomes in clinical trials of pharmacological and nonpharmacological pain treatments. We highlight the potential benefit of adjusting for participants' expectations in clinical trial analyses and draw on findings from patient interviews to discuss critical issues related to measurement of expectations. We conclude with suggestions regarding future studies focused on better understanding the utility of incorporating these measures into clinical trial analyses. PERSPECTIVE: This focus article provides an overview of the relationship between participants' baseline expectations and pain-related outcomes in the setting of clinical trials of chronic pain treatments. Systematic research focused on the measurement of expectations and the impact of adjusting for expectations in clinical trial analyses may improve assay sensitivity.

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.

Exploring Patients' Understanding of Chemotherapy-Induced Peripheral Neuropathy.

Little quantitative evidence exists surrounding patients' level of understanding of chemotherapy-induced peripheral neuropathy (CIPN) symptoms (numbness, tingling, pain in the hands/feet) and consequences (e.g., negatively affect physical functioning or chemotherapy dosing) at the beginning of chemotherapy. The purpose of this cross-sectional, secondary analysis was to describe CIPN knowledge and education patterns among adults early in a course of neurotoxic chemotherapy for the treatment of cancer (< three infusions). Following consent, participants completed an electronic questionnaire about their perceptions of CIPN symptoms, incidence, and education. Participants (N = 92) were mainly female (76%), white (91%), and diagnosed with breast (46%) or gastrointestinal (40%) cancers. Most participants without CIPN (n = 48) did not expect to develop CIPN (45%) or were unaware of CIPN as a side-effect (30%). Furthermore, 71% of participants without CIPN (n = 31) estimated CIPN to occur in ≤ 30% of patients receiving neurotoxic chemotherapy. Overall, participants learned about CIPN from their doctor or nurse prior to beginning chemotherapy (90%). Clinicians delivered education about CIPN symptoms (75%), but less frequently delivered education about CIPN management (14%), or the impact of CIPN on the ability to continue chemotherapy (16%) or physical functioning (24%). Finally, participants reported that a discussion with their doctor/nurse would be the best way to learn about CIPN (92%). Results revealed that participants without CIPN were largely unaware of the adverse consequences or incidence of CIPN during treatment. Further research is needed to investigate optimal methods to promote patient-clinician communication about CIPN during chemotherapy to enhance patients' retention of CIPN information and activation in their care.

Identifying participants' preferences for modifiable chemotherapy-induced peripheral neuropathy prevention clinical trial factors: an adaptive choice-based conjoint analysis.

PURPOSE: There are no recommended treatments for chemotherapy-induced peripheral neuropathy (CIPN) prevention. Recruitment to CIPN prevention clinical trials is challenging because it is difficult to enroll patients between the time of cancer diagnosis and the initiation of neurotoxic chemotherapy. The purpose of this exploratory-sequential mixed-methods study was to determine patients' preferences that could affect the choice to participate in CIPN prevention clinical trials. METHODS: First, twenty cognitive interviews were conducted with adults who completed less than three neurotoxic chemotherapy infusions to clarify clinical trial attributes and levels thought to be important to patients when deciding whether to enroll in CIPN prevention trials (i.e., type of treatment, clinical tests, reimbursement, survey delivery; length of visits, timing of follow-up, when to begin treatment). Second, another eighty-eight patients completed an adaptive choice-based conjoint analysis survey that incorporated the finalized attributes and levels. Each level was assigned a part-worth utility score using Hierarchical Bayes Estimation. The relative importance of each attribute was calculated. RESULTS: The attributes with the highest relative importance values were type of treatment (27.1%) and length of study visits (20.2%). The preferred levels included non-medicine treatment (53.49%), beginning treatment after experiencing CIPN (60.47%), email surveys (63.95%), assessments that include surveys and clinical exams (39.53%), under 30-min visits (44.19%), $50/week reimbursement (39.53%), and 1-month post-chemotherapy follow-up visits (32.56%). CONCLUSIONS: Patients' preferences for participation may be included in the design of future CIPN prevention clinical trials to potentially bolster study enrollment.

Initial Content Validation and Roadmap for a New Patient-Reported Outcome Measure of Pain Intensity.

Measures of pain intensity (eg, numeric rating scales [NRS]) are widely used in clinical research and practice. While these measures have evidence for validity and reliability, poor standardization of instructions, and response options limits precision of pain assessment, allows for inconsistency in interpretation, and presents a challenge for comparison and aggregation of study results. Despite these pitfalls, the 0 to 10 NRS remains the most commonly used primary outcome measure in clinical trials of pain treatments and is the core measure recommended by regulatory agencies. The purpose of this study was to describe the first phase in the development of a pain intensity measure that is easily interpretable, psychometrically sound, and that adheres to FDA qualification processes. The Analgesic, Anesthetic, and Addiction Clinical Trial, Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership conducted concept elicitation interviews (N = 44; 22 with acute pain; 22 with chronic pain) to understand the patient perspective on rating pain intensity and to identify actionable suggestions for improved clarity and meaningfulness of instructions, recall periods, and response options. This article summarizes interview findings, describes how patient input and FDA feedback informed preliminary candidate measures, and provides an overview of the FDA qualification process. PERSPECTIVE: Concept elicitation interviews informed the development of content-valid candidate measures of acute and chronic pain intensity for planned use in clinical trials of pain treatments, and comprise the initial stage in FDA clinical outcome assessment qualification. Measures will subsequently be evaluated through cognitive interviews and a series of psychometric studies.

Evaluation of the psychometric properties of patient-reported and clinician-reported outcome measures of chemotherapy-induced peripheral neuropathy: a COSMIN systematic review protocol.

INTRODUCTION: Chemotherapy-induced peripheral neuropathy (CIPN) is a poorly understood side effect of many antineoplastic agents. Patients may experience sensory, motor and autonomic symptoms, negatively impacting quality of life. A gold-standard assessment methodology has yet to be determined, limiting efforts to identify effective agents to prevent or treat CIPN. METHODS AND ANALYSIS: This is a protocol of a systematic review of psychometric analyses of CIPN Clinician Reported Outcome Measures (ClinROM) and Patient-Reported Outcome Measures (PROM) among adults receiving, or who had previously received chemotherapy for cancer. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) quality ratings will be compared across studies and across ClinROMs and PROMs. Studies reporting psychometric proprieties of CIPN ClinROMs and/or PROMs among adults aged ≥18 years will be eligible for inclusion, with no restriction on language or year of publication. MEDLINE, Embase, CINAHL and APA PsycINFO databases will be searched from inception to 31 December 2021. Study characteristics, measurement properties of the ClinROMs and/or PROMs and the CIPN definitions will be extracted. The Synthesis Without Meta-analysis guideline will be used to guide data synthesis. The COSMIN Risk of Bias checklist will be used by two independent raters to assess methodological quality. Subgroup analyses by age, chemotherapy type, and study timing in relation to the delivery of chemotherapy will be carried out where data are available. An adapted version of Outcome Measures in Rheumatology filter 2.1 will be used to provide a best-evidence synthesis of CIPN ClinROMs and PROMs and to recommend a CIPN assessment tool for clinical and research settings. ETHICS AND DISSEMINATION: Ethical approval is not necessary to be obtained for this systematic review protocol. Results will be disseminated to clinicians and policy-makers by publication in a peer-reviewed journal and by presenting at relevant conferences. PROSPERO REGISTRATION NUMBER: CRD42021278168.

Predicting Treatment Response with Sensory Phenotyping in Post-Traumatic Neuropathic Pain.

OBJECTIVE: Currently available treatments for neuropathic pain are only modestly efficacious when assessed in randomized clinical trials and work for only some patients in the clinic. Induced-pain or gain-of-function phenotypes have been shown to predict response to analgesics (vs placebos) in patients with neuropathic pain. However, the predictive value of these phenotypes has never been studied in post-traumatic neuropathic pain. METHODS: Mixed-effects models for repeated measures were used to evaluate the efficacy of pregabalin vs placebo in subgroups with induced-pain phenotypes (i.e., hyperalgesia or allodynia) in data from a recent, multinational randomized clinical trial (N = 539) that identified phenotypic subgroups through the use of a structured clinical exam. RESULTS: The difference in mean pain score between the active and placebo groups (i.e., delta) after 15 weeks of treatment for the subgroup with hyperalgesia was -0.76 (P = 0.001), compared with 0.19 (P = 0.47) for the subgroup that did not have hyperalgesia. The treatment-by-phenotype interaction, which tests whether subgroups have statistically different treatment responses, was significant (P = 0.0067). The delta for the subgroup with allodynia was -0.31 (P = 0.22), compared with -0.30 (P = 0.22) for the subgroup that did not have allodynia (treatment-by-phenotype interaction P = 0.98). CONCLUSIONS: These data suggest that hyperalgesia, but not allodynia, predicts response to pregabalin in patients with chronic post-traumatic neuropathic pain. This study extends the growing data supporting the utility of induced-pain phenotypes to predict response to analgesics in post-traumatic neuropathic pain. Sensory phenotyping in large, multisite trials through the use of a structured clinical exam has the potential to accelerate the development of new analgesics and improve the generalizability of clinical trial results.

Partnering with patients in clinical trials of pain treatments: a narrative review.

ABSTRACT: The interest and the rationale for meaningful engagement of patients as partners in clinical trials of pain treatments has been increasing. No specific guidance on patient engagement for pain research studies currently exists; thus, the goal of this narrative review was to provide a historical perspective and a current evaluation of the literature on engaging patients as partners in clinical studies in general and in pain-related studies more specifically. We described how regulatory and funding agencies have developed approaches to incorporate input from patients and patient partners in their decision-making processes. We provided an overview on key practices of patient recruitment and engagement as partners in clinical research and highlighted the perceived benefits and challenges of such partnerships. We summarized factors that can facilitate or hinder meaningful patient engagement in clinical trials of pain treatments and outlined gaps that future research should address to optimize patient-centered clinical research.

Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations.

ABSTRACT: Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.