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.

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.

Evaluating the stability of opioid efficacy over 12 months in patients with chronic noncancer pain who initially demonstrate benefit from extended release oxycodone or hydrocodone: harmonization of Food and Drug Administration patient-level drug safety study data

ABSTRACT

Opioids relieve acute pain, but there is little evidence to support the stability of the benefit over long-term treatment of chronic noncancer pain. Previous systematic reviews consider only group level published data which did not provide adequate detail. Our goal was to use patient-level data to explore the stability of pain, opioid dose, and either physical function or pain interference in patients treated for 12 months with abuse deterrent formulations of oxycodone and hydrocodone. All available studies in the Food and Drug Administration Document Archiving, Reporting, and Regulatory Tracking System were included. Patient-level demographics, baseline data, exposure, and outcomes were harmonized. Individual patient slopes were calculated from a linear model of pain, physical function, and pain interference to determine response over time. Opioid dose was summarized by change between baseline and the final month of observation. Patients with stable or less pain, stable or lower opioid dose, and stable or better physical function (where available) met our prespecified criteria for maintaining long-term benefit from chronic opioids. Of the complete data set of 3192 patients, 1422 (44.5%) maintained their pain level and opioid dose. In a secondary analysis of 985 patients with a measured physical function, 338 (34.3%) maintained their physical function in addition to pain and opioid dose. Of 2040 patients with pain interference measured, 788 (38.6%) met criteria in addition. In a carefully controlled environment, about one-third of patients successfully titrated on opioids to treat chronic noncancer pain demonstrated continued benefit for up to 12 months.

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.

Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations

Interpreting randomized clinical trials (RCTs) is crucial to making decisions regarding the use of analgesic treatments in clinical practice. In this article, we report on an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus meeting organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks, the purpose of which was to recommend approaches that facilitate interpretation of analgesic RCTs. We review issues to consider when drawing conclusions from RCTs, as well as common methods for reporting RCT results and the limitations of each method. These issues include the type of trial, study design, statistical analysis methods, magnitude of the estimated beneficial and harmful effects and associated precision, availability of alternative treatments and their benefit-risk profile, clinical importance of the change from baseline both within and between groups, presentation of the outcome data, and the limitations of the approaches used.

A Real-World Study Using Claims Data to Evaluate Possible Failure of Opioid Treatment Regimens Among Patients with Hip and/or Knee Osteoarthritis in the US

Background

Although opioids may be used in the management of pain in patients with osteoarthritis (OA), there is a dearth of real-world data characterizing opioid regimen failure in these patients.

Objective

Using claims data, this study explored measures that may be potentially indicative of opioid treatment failure and the association of such potential failure with health care resource utilization (HRU) and costs.

Patients and Methods

Using a national employer-sponsored insurance claims database covering the years 2011–2016, this retrospective longitudinal study identified adults with hip/knee osteoarthritis who filled ≥1 opioid prescription (index event) and had continuous health plan enrollment 6 months pre- and ≥12 months post-index. Index opioid regimen intensity was defined in the 3-month post-index period by frequency, average daily dose, and duration of action. Possible index opioid regimen failure was defined as an increase in opioid regimen intensity, addition of a non-opioid pain medication, joint surgery, or opioid-abuse-related events. One-year follow-up HRU and costs were compared between those with possible treatment failure and those without.

Results

Among 271,512 OA patients (61.5% knee; 11.1% hip; 27.4% both), 34.9% met the definition of possible index opioid regimen failure within a year: increased regimen intensity (16.1%), joint surgery (14.0%), addition of non-opioid pain medication (11.4%), and opioid-abuse-related events (1.9%). Rates of possible failure generally increased with higher index regimen intensity. Compared with those who did not fail, those who potentially failed their index treatment regimen had significantly higher HRU (P<0.001), and all-cause ($36,699 vs $15,114) and osteoarthritis-related costs ($17,298 vs $1,967) (both P<0.0001).

Conclusion

Among OA patients treated with opioids, approximately one-third may fail their index opioid regimen within a year and incur significantly higher HRU and costs than those without. Further research is needed to validate these findings with clinical outcomes.

Short-acting and Long-acting Opioids Utilization among Women Diagnosed with Endometriosis in the United States: A Population-based Claims Study

STUDY OBJECTIVE

To determine the prevalence and pattern of opioid use in endometriosis and the characteristics of patients prescribed an opioid using medical insurance claims data.

DESIGN

We performed a retrospective cohort analysis of data from the Truven MarketScan Commercial database for the period of January 1, 2011 to December 31, 2016.

SETTING

The Truven database includes inpatient, outpatient, and prescription claims covering more than 115 million unique individuals and over 36 million inpatient hospital discharges across multiple payer types and all 50 states.

PATIENTS

Women with endometriosis were defined as those with 1 inpatient or 2 outpatient codes for endometriosis.

INTERVENTIONS

No interventions were assigned. Women who filled an opioid prescription within 12 months of diagnosis were placed in the opioid cohort and women who did not fill an opioid prescription were placed in the nonopioid cohort.

MEASUREMENTS AND MAIN RESULTS

Baseline characteristics were evaluated 12 months preindex (date of the first diagnosis) and opioid use was assessed for 12 months after the index date. The dataset included 58 472 women with endometriosis. Of these, 61.7% filled an opioid prescription during the study period. More than 95% filled prescriptions for short-acting opioids (SAOs) only, 4.1% filled prescriptions for both SAOs and extended-release/long-acting opioids (LAOs), and 0.6% filled prescriptions for LAOs only. Patients who filled an opioid prescription had higher baseline comorbidities (especially gynecologic and chronic pain comorbidities) and endometriosis-related medication use compared with patients who did not fill an opioid prescription during the study period. Patients who filled both LAO and SAO prescriptions had the highest total days' supply of opioids, the proportion of days covered by prescriptions, and morphine equivalent daily dose. These patients also had the highest proportions of opioid switching and dose augmentation. Statistical trends in data were not substantially altered when analyses excluded patients with chronic pain comorbidities or surgical opioid prescriptions.

CONCLUSION

Although opioids are not a recommended treatment for endometriosis, more than half of our cohort filled an opioid prescription within 1 year after a first recorded diagnosis of endometriosis. Patients who filled an opioid prescription tended to use more endometriosis-related medications and have a higher comorbidity burden. Additional research is necessary to better understand the reasons and outcomes associated with opioid utilization in endometriosis and to determine if there is a more effective pain management treatment plan for patients taking opioids.

Healthcare utilization and cost burden among women with endometriosis by opioid prescription status in the first year after diagnosis: a retrospective claims database analysis

Aims: Opioids do not represent standard therapy for endometriosis; however, women with endometriosis are frequently prescribed an opioid to manage related abdominal or pelvic pain. The aim of this study was to evaluate the impact of opioid use on endometriosis-related economic and healthcare burden in the United States.Materials and methods: We performed a retrospective, propensity-matched cohort analysis of the Truven MarketScan Commercial database from 1 January 2011 to 31 December 2016. Eligible women had at least 1 inpatient or 2 outpatient codes for endometriosis and 12 months of continuous enrollment before and after the index date (i.e. first recorded endometriosis diagnosis). The primary analysis examined healthcare costs and utilization for 12 months after the index date in women who filled at least 1 opioid prescription versus those who did not. The secondary analysis examined healthcare costs and utilization by the pattern of opioid use.Results: The primary analysis matched 43,516 women across 2 groups and the secondary analysis matched 13,230 women across 5 groups. In the primary analysis, total 12-month healthcare costs were significantly higher in the opioid group compared to the non-opioid group ($29,236.00 vs. $18,466.00, respectively; p < .001); the same pattern was observed for all healthcare utilization parameters. In the secondary analysis, higher morphine equivalent daily dose and proportion of days covered were associated with the highest healthcare costs and utilization compared to the non-opioid group.Limitations: Retrospective design and inability to confirm whether filled opioid prescriptions were actually taken.Conclusions: Filling an opioid prescription within 1 year after an endometriosis diagnosis was associated with significant excess healthcare burden. Patients prescribed an opioid may experience inadequate symptom management and benefit from the use of disease-specific, non-opioid therapies.

Improving Study Conduct and Data Quality in Clinical Trials of Chronic Pain Treatments: IMMPACT Recommendations

The estimated probability of progressing from phase 3 analgesic clinical trials to regulatory approval is approximately 57%, suggesting that a considerable number of treatments with phase 2 trial results deemed sufficiently successful to progress to phase 3 do not yield positive phase 3 results. Deficiencies in the quality of clinical trial conduct could account for some of this failure. An Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting was convened to identify potential areas for improvement in trial conduct in order to improve assay sensitivity (ie, ability of trials to detect a true treatment effect). We present recommendations based on presentations and discussions at the meeting, literature reviews, and iterative revisions of this article. The recommendations relate to the following areas: 1) study design (ie, to promote feasibility), 2) site selection and staff training, 3) participant selection and training, 4) treatment adherence, 5) data collection, and 6) data and study monitoring. Implementation of these recommendations may improve the quality of clinical trial data and thus the validity and assay sensitivity of clinical trials. Future research regarding the effects of these strategies will help identify the most efficient use of resources for conducting high quality clinical trials. PERSPECTIVE: Every effort should be made to optimize the quality of clinical trial data. This manuscript discusses considerations to improve conduct of pain clinical trials based on research in multiple medical fields and the expert consensus of pain researchers and stakeholders from academia, regulatory agencies, and industry.

Assessment of potentially abuse-related events in two phase 3 studies of NKTR-181, a novel opioid analgesic, using the MADDERS® system (Misuse, Abuse, and Diversion Drug Event Reporting System)

Objective: To prospectively evaluate the abuse potential of NKTR-181, a novel opioid analgesic, in two phase 3 clinical trials using a newly developed reporting system: the Misuse, Abuse, and Diversion Drug Event Reporting System (MADDERS®).Methods: SUMMIT-07 was an enriched enrollment randomized withdrawal study that examined the safety and efficacy of NKTR-181 across 12 weeks in opioid-naïve subjects with chronic low back pain. SUMMIT-LTS was a 52 week open-label study in opioid-naïve and experienced subjects with chronic low back pain or noncancer pain rolled over from SUMMIT-07 or enrolled de novo. System evaluations were triggered by adverse events of interest and drug accountability discrepancies signaling potentially abuse-related events. Each event was assigned a primary classification and supplementary classification(s) by investigators and by a blinded, independent committee of substance abuse experts (adjudicators). At the final study visit, investigators administered a survey to subjects to identify overlooked events of interest.Results: Seventy-nine (6.6%) of 1189 subjects were associated with 86 events in SUMMIT-07 and 51 (8.0%) of 638 subjects were associated with 59 events in SUMMIT-LTS. Most events were attributed to "Withdrawal" and, primarily in SUMMIT-07, "Therapeutic Error" (unintentional overuse) or "Misuse" (intentional overuse for a therapeutic purpose) of study medication. Adjudicators identified five possible "Abuse" events (three NKTR-181, two placebo) in SUMMIT-07 and four possible "Abuse" events (all NKTR-181) in SUMMIT-LTS.Conclusions: The MADDERS® system discerns potentially abuse-related events and identified low rates of withdrawal and a low risk of abuse potential, diversion or addiction associated with NKTR-181 in phase 3 trials.

Demonstrating Heterogeneity of Treatment Effects Among Patients: An Overlooked but Important Step Toward Precision Medicine

Although heterogeneity in the observed outcomes in clinical trials is often assumed to reflect a true heterogeneous response, it could actually be due to random variability. This retrospective analysis of four randomized, double-blind, placebo-controlled multiperiod (i.e., episode) crossover trials of fentanyl for breakthrough cancer pain illustrates the use of multiperiod crossover trials to examine heterogeneity of treatment response. A mixed-effects model, including fixed effects for treatment and episode and random effects for patient and treatment-by-patient interaction, was used to assess the heterogeneity in patients' responses to treatment during each episode. A significant treatment-by-patient interaction was found for three of four trials (P < 0.05), suggesting heterogeneity of the effect of fentanyl among different patients in each trial. Similar analyses in other therapeutic areas could identify conditions and therapies that should be investigated further for predictors of treatment response in efforts to maximize the efficiency of developing precision medicine strategies.

Trial designs for chemotherapy-induced peripheral neuropathy prevention: ACTTION recommendations

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and potentially dose-limiting side effect of neurotoxic chemotherapies. No therapies are available to prevent CIPN. The small number of positive randomized clinical trials (RCTs) evaluating preventive therapies for CIPN provide little guidance to inform the design of future trials. Moreover, the lack of consensus regarding major design features in this area poses challenges to development of new therapies. An Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities and Networks (ACTTION)-Consortium on Clinical Endpoints and Procedures for Peripheral Neuropathy Trials (CONCEPPT) meeting attended by neurologists, oncologists, pharmacists, clinical trialists, statisticians, and regulatory experts was convened to discuss design considerations and provide recommendations for CIPN prevention trials. This article outlines considerations related to design of RCTs that evaluate preventive therapies for CIPN including (1) selection of eligibility criteria (e.g., cancer types, chemotherapy types, inclusion of preexisting neuropathy); (2) selection of outcome measures and endpoints, including those that incorporate alterations in chemotherapy dosing, which may affect the rate of CIPN development and its severity; (3) potential effects of the investigational therapy on the efficacy of chemotherapy; and (4) sample size estimation. Our hope is that attention to the design considerations and recommendations outlined in this article will improve the quality and assay sensitivity of CIPN prevention trials and thereby accelerate the identification of efficacious therapies.

Accurate pain reporting training diminishes the placebo response: Results from a randomised, double-blind, crossover trial

Analgesic trials frequently fail to demonstrate efficacy of drugs known to be efficacious. Poor pain reporting accuracy is a possible source for this low essay-sensitivity. We report the effects of Accurate-Pain-Reporting-Training (APRT) on the placebo response in a trial of Pregabalin for painful-diabetic-neuropathy. The study was a two-stage randomized, double-blind trial: In Stage-1 (Training) subjects were randomized to APRT or No-Training. The APRT participants received feedback on the accuracy of their pain reports in response to mechanical stimuli, measured by R-square score. In Stage-2 (Evaluation) all subjects entered a placebo-controlled, cross-over trial. Primary (24-h average pain intensity) and secondary (current, 24-h worst, and 24-h walking pain intensity) outcome measures were reported. Fifty-one participants completed the study. APRT patients (n = 28) demonstrated significant (p = 0.036) increases in R-square scores. The APRT group demonstrated significantly (p = 0.018) lower placebo response (0.29 ± 1.21 vs. 1.48 ± 2.21, mean difference ± SD = -1.19±1.73). No relationships were found between the R-square scores and changes in pain intensity in the treatment arm. In summary, our training successfully increased pain reporting accuracy and resulted in a diminished placebo response. Theoretical and practical implications are discussed.

Effects of a Single Intra-Articular Injection of a Microsphere Formulation of Triamcinolone Acetonide on Knee Osteoarthritis Pain: A Double-Blinded, Randomized, Placebo-Controlled, Multinational Study

BACKGROUND

Intra-articular corticosteroids relieve osteoarthritis pain, but rapid systemic absorption limits efficacy. FX006, a novel, microsphere-based, extended-release triamcinolone acetonide (TA) formulation, prolongs TA joint residence and reduces systemic exposure compared with standard TA crystalline suspension (TAcs). We assessed symptomatic benefits and safety of FX006 compared with saline-solution placebo and TAcs.

METHODS

In this Phase-3, multicenter, double-blinded, 24-week study, adults ≥40 years of age with knee osteoarthritis (Kellgren-Lawrence grade 2 or 3) and average-daily-pain (ADP)-intensity scores of ≥5 and ≤9 (0 to 10 numeric rating scale) were centrally randomized (1:1:1) to a single intra-articular injection of FX006 (32 mg), saline-solution placebo, or TAcs (40 mg). The primary end point was change from baseline to week 12 in weekly mean ADP-intensity scores for FX006 compared with saline-solution placebo. Secondary end points were area-under-effect (AUE) curves of the change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with saline-solution placebo, AUE curves of the change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with TAcs, change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with TAcs, and AUE curves of the change in weekly mean ADP-intensity scores from baseline to week 24 for FX006 compared with saline-solution placebo. Exploratory end points included week-12 changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Injury and Osteoarthritis Outcome Score Quality of Life (KOOS-QOL) subscale scores for FX006 compared with saline-solution placebo and TAcs. Adverse events were elicited at each inpatient visit.

RESULTS

The primary end point was met. Among 484 treated patients (n = 161 for FX006, n = 162 for saline-solution placebo, and n = 161 for TAcs), FX006 provided significant week-12 improvement in ADP intensity compared with that observed for saline-solution placebo (least-squares mean change from baseline: -3.12 versus -2.14; p < 0.0001) indicating ∼50% improvement. FX006 afforded improvements over saline-solution placebo for all secondary and exploratory end points (p < 0.05). Improvements in osteoarthritis pain were not significant for FX006 compared with TAcs using the ADP-based secondary measures. Exploratory analyses of WOMAC-A, B, and C and KOOS-QOL subscales favored FX006 (p ≤ 0.05). Adverse events were generally mild, occurring at similar frequencies across treatments.

CONCLUSIONS

FX006 provided significant, clinically meaningful pain reduction compared with saline-solution placebo at week 12 (primary end point).

LEVEL OF EVIDENCE

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

The Potential Role of Sensory Testing, Skin Biopsy, and Functional Brain Imaging as Biomarkers in Chronic Pain Clinical Trials: IMMPACT Considerations

Valid and reliable biomarkers can play an important role in clinical trials as indicators of biological or pathogenic processes or as a signal of treatment response. Currently, there are no biomarkers for pain qualified by the U.S. Food and Drug Administration or the European Medicines Agency for use in clinical trials. This article summarizes an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting in which 3 potential biomarkers were discussed for use in the development of analgesic treatments: 1) sensory testing, 2) skin punch biopsy, and 3) brain imaging. The empirical evidence supporting the use of these tests is described within the context of the 4 categories of biomarkers: 1) diagnostic, 2) prognostic, 3) predictive, and 4) pharmacodynamic. Although sensory testing, skin punch biopsy, and brain imaging are promising tools for pain in clinical trials, additional evidence is needed to further support and standardize these tests for use as biomarkers in pain clinical trials.

PERSPECTIVE

The applicability of sensory testing, skin biopsy, and brain imaging as diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for use in analgesic treatment trials is considered. Evidence in support of their use and outlining problems is presented, as well as a call for further standardization and demonstrations of validity and reliability.

Development and preliminary validation of the focused analgesia selection test to identify accurate pain reporters

Clinical trials of analgesics have been plagued with poor assay sensitivity due, in part, to variability in subjects' pain reporting. Herein, we develop and evaluate the focused analgesia selection test (FAST), a method to measure patients' pain reporting skills. Subjects with osteoarthritis of the hip, knee, and/or ankle with pain intensity of ≥3/10 on a 0-10 numerical rating scale were enrolled. Subjects underwent the FAST procedure, which consists of recording subjects' pain reports in response to repeated administration of thermal noxious stimuli of various intensities applied on the arm with the Medoc^® Thermal Sensory Analyzer II. Subjects also rated non-noxious stimuli consisting of visual contrast rating. After performing an exercise task, subjects also rated clinical pain and were asked to report whether their pain had increased, decreased, or stayed the same. Overall, 88 subjects were enrolled, and 83 were included in the analyses. FAST's outcomes including the R², intraclass correlation coefficient (ICC), and coefficient of variation (CoV) indicated that subjects' pain reporting skills were widely distributed. Higher FAST ICC significantly predicted greater changes in clinical pain following exercise (p=0.017), whereas the visual contrast test did not predict postexercise pain. FAST is the first method that measures subjects' pain reporting skills. Using FAST to enrich clinical trials with "good" pain reporters (with high FAST ICC) could increase assay sensitivity. Further evaluation of FAST is ongoing.

Insights and issues from FDA Advisory Committee meetings on abuse-deterrent opioids

It is the current policy of the US Food and Drug Administration (FDA) to convene expert Advisory Committees to provide input on key regulatory decisions regarding opioid products, including approval and labeling of opioid abuse-deterrent formulations (ADFs). Advisory Committee meetings on ADF opioids consider whether the laboratory and clinical data submitted by the sponsor are sufficient to support marketing approval and labeling of the product with properties expected to deter abuse by specific routes of abuse (ie, oral, intranasal, intravenous). The FDA has typically followed the approval and labeling recommendations for ADFs reviewed by its Advisory Committees, highlighting the importance of these meetings in the regulatory approval process. This review describes common issues considered by Advisory Committees for ADF opioids as well as insights on how to prepare for these meetings based on recent relevant experience and regulatory decisions.

Development and feasibility of the misuse, abuse, and diversion drug event reporting system (MADDERS®)

BACKGROUND AND OBJECTIVES

Inappropriate use of analgesic drugs has become increasingly pervasive over the past decade. Currently, drug abuse potential is primarily assessed post-marketing; no validated tools are available to assess this potential in phase II and III clinical trials. This paper describes the development and feasibility testing of a Misuse, Abuse, and Diversion Drug Event Reporting System (MADDERS), which aims to identify potentially abuse-related events and classify them according to a recently developed classification scheme, allowing the quantification of these events in clinical trials.

METHODS

The system was initially conceived and designed with input from experts and patients, followed by field-testing to assess its feasibility and content validity in both completed and ongoing clinical trials.

RESULTS

The results suggest that MADDERS is a feasible system with initial validity. It showed higher rates of the triggering events in subjects taking medications with known abuse potential than in patients taking medications without abuse potential. Additionally, experts agreed on the classification of most abuse-related events in MADDERS.

DISCUSSION AND CONCLUSIONS

MADDERS is a new systematic approach to collect information on potentially abuse-related events in clinical trials and classify them. The system has demonstrated feasibility for implementation. Additional research is ongoing to further evaluate its validity.

SCIENTIFIC SIGNIFICANCE

Currently, there are no validated tools to assess drug abuse potential during clinical trials. Because of its ease of implementation, its systematic approach, and its preliminary validation results, MADDERS could provide such a tool for clinical trials. (Am J Addict 2016;25:641-651).

Root cause analysis of prescription opioid overdoses

Overdoses (ODs) of prescription opioids (RxOs) have become a major public health issue in the United States.

OBJECTIVE

To determine the root causes of accidental prescription opioid overdoses (RxO-OD).

DESIGN/SETTING/PARTICIPANTS/INTERVENTION

The authors conducted a root cause analysis using the Antecedent Target-Measurement method, interviewing three types of key informants: survivors of RxO-ODs, family members, and clinical experts.

RESULTS

Ten survivors, five family members, and three experts were interviewed. Proximal causes of RxO-ODs described by survivors and family members were recent RxO dose escalation (n = 9), polysubstance use (n = 5), and polypharmacy use (n = 3). Proximal causes were elicited by the following six antecedent causes: wanting to feel good/high (n = 9), perceived tolerance to RxO (n = 6), didn't know/believe it was dangerous (n = 5), wanting to reduce psychosocial pain (n = 5), wanting to reduce physical pain (n = 4), and wanting to avoid discomfort due to withdrawal symptoms (n = 4). RxOs involved in the OD were either prescribed by a doctor (n = 7), purchased from a dealer (n = 6), given/purchased from family/friends (n = 3), or stolen from family (n = 1). Psychosocial stressors (n = 9), chronic recurrent depression (n = 3), and chronic substance abuse/addiction (n = 4) were also distal and proximal causes of OD. Experts cited similar causes but added prescriberrelated causes (eg, inadequate training) and healthcare system and culture.

CONCLUSIONS

Patients at risk for OD can be identified and ODs potentially prevented. Opportunities for intervention include routine screening of patients using RxOs for psychosocial distress and coping, flagging of high-risk patients, care pathways for high-risk patients, clinician and patient training on OD prevention, and developing abuse-deterrent formulations of RxOs.

Instruments to Identify Prescription Medication Misuse, Abuse, and Related Events in Clinical Trials: An ACTTION Systematic Review

Measurement of inappropriate medication use events (eg, abuse or misuse) in clinical trials is important in characterizing a medication's abuse potential. However, no gold standard assessment of inappropriate use events in clinical trials has been identified. In this systematic review, we examine the measurement properties (ie, content validity, cross-sectional reliability and construct validity, longitudinal construct validity, ability to detect change, and responder definitions) of instruments assessing inappropriate use of opioid and nonopioid prescription medications to identify any that meet U.S. and European regulatory agencies' rigorous standards for outcome measures in clinical trials. Sixteen published instruments were identified, most of which were not designed for the selected concept of interest and context of use. For this reason, many instruments were found to lack adequate content validity (or documentation of content validity) to evaluate current inappropriate medication use events; for example, evaluating inappropriate use across the life span rather than current use, including items that did not directly assess inappropriate use (eg, questions about anger), or failing to capture information pertinent to inappropriate use events (eg, intention and route of administration). In addition, the psychometric data across all instruments were generally limited in scope. A further limitation is the heterogeneous, nonstandardized use of inappropriate medication use terminology. These observations suggest that available instruments are not well suited for assessing current inappropriate medication use within the specific context of clinical trials. Further effort is needed to develop reliable and valid instruments to measure current inappropriate medication use events in clinical trials.

PERSPECTIVE

This systematic review evaluates the measurement properties of inappropriate medication use (eg, abuse or misuse) instruments to determine whether any meet regulatory standards for clinical trial outcome measures to assess abuse potential.

Determining the clinical importance of treatment benefits for interventions for painful orthopedic conditions

The overarching goals of treatments for orthopedic conditions are generally to improve or restore function and alleviate pain. Results of clinical trials are generally used to determine whether a treatment is efficacious; however, a statistically significant improvement may not actually be clinically important, i.e., meaningful to the patient. To determine whether an intervention has produced clinically important benefits requires a two-step process: first, determining the magnitude of change considered clinically important for a particular measure in the relevant population and, second, applying this yardstick to a patient's data to determine whether s/he has benefited from treatment. Several metrics have been devised to quantify clinically important differences, including the minimum clinically important difference (MCID) and clinically important difference (CID). Herein, we review the methods to generate the MCID and other metrics and their use and interpretation in clinical trials and practice. We particularly highlight the many pitfalls associated with the generation and utilization of these metrics that can impair their correct use. These pitfalls include the fact that different pain measures yield different MCIDs, that efficacy in clinical trials is impacted by various factors (population characteristics, trial design), that the MCID value is impacted by the method used to calculate it (anchor, distribution), by the type of anchor chosen and by the definition (threshold) of improvement. The MCID is also dependent on the population characteristics such as disease type and severity, sex, age, etc. For appropriate use, the MCID should be applied to changes in individual subjects, not to group changes. The MCID and CID are useful tools to define general guidelines to determine whether a treatment produces clinically meaningful effects. However, the many pitfalls associated with these metrics require a detailed understanding of the methods to calculate them and their context of use. Orthopedic surgeons that will use these metrics need to carefully understand them and be aware of their pitfalls.

Validation of the Short-form McGill Pain Questionnaire-2 (SF-MPQ-2) in acute low back pain

The Short-form McGill Pain Questionnaire (SF-MPQ-2) assesses the major symptoms of both neuropathic and nonneuropathic pain and can be used in studies of epidemiology, natural history, pathophysiologic mechanisms, and treatment response. Previous research has demonstrated its reliability, validity, and responsiveness in diverse samples of patients with chronic pain. However, the SF-MPQ-2 has not been evaluated for use in patients with acute pain. Data were examined from a double-blind, randomized clinical trial of immediate-release tapentadol versus immediate-release oxycodone in patients with acute low back and associated radicular leg pain (N = 666). Analyses of internal consistency, convergent validity, and confirmatory factor structure were conducted using baseline data, and analyses of responsiveness were conducted using baseline and endpoint data. The SF-MPQ-2 total score and its 4 subscale scores (continuous pain, intermittent pain, predominantly neuropathic pain, and affective descriptors) generally showed good psychometric properties and 1) were internally consistent, 2) displayed good convergent validity, 3) fit the a priori factor structure, and 4) were highly responsive to analgesic treatment. These data extend previous evidence of the reliability, validity, and responsiveness of the SF-MPQ-2 in patients with chronic pain to those with acute low back and associated radicular leg pain.

PERSPECTIVE

Considered together with the results of other recent studies, the data suggest that the SF-MPQ-2 can provide a valid, responsive, and efficient assessment of both neuropathic and nonneuropathic pain qualities for clinical trials and other clinical research examining patients with various acute and chronic pain conditions.

Reporting of sample size calculations in analgesic clinical trials: ACTTION systematic review

Sample size calculations determine the number of participants required to have sufficiently high power to detect a given treatment effect. In this review, we examined the reporting quality of sample size calculations in 172 publications of double-blind randomized controlled trials of noninvasive pharmacologic or interventional (ie, invasive) pain treatments published in European Journal of Pain, Journal of Pain, and Pain from January 2006 through June 2013. Sixty-five percent of publications reported a sample size calculation but only 38% provided all elements required to replicate the calculated sample size. In publications reporting at least 1 element, 54% provided a justification for the treatment effect used to calculate sample size, and 24% of studies with continuous outcome variables justified the variability estimate. Publications of clinical pain condition trials reported a sample size calculation more frequently than experimental pain model trials (77% vs 33%, P < .001) but did not differ in the frequency of reporting all required elements. No significant differences in reporting of any or all elements were detected between publications of trials with industry and nonindustry sponsorship. Twenty-eight percent included a discrepancy between the reported number of planned and randomized participants. This study suggests that sample size calculation reporting in analgesic trial publications is usually incomplete. Investigators should provide detailed accounts of sample size calculations in publications of clinical trials of pain treatments, which is necessary for reporting transparency and communication of pre-trial design decisions.

PERSPECTIVE

In this systematic review of analgesic clinical trials, sample size calculations and the required elements (eg, treatment effect to be detected; power level) were incompletely reported. A lack of transparency regarding sample size calculations may raise questions about the appropriateness of the calculated sample size.

Research designs for proof-of-concept chronic pain clinical trials: IMMPACT recommendations

Proof-of-concept (POC) clinical trials play an important role in developing novel treatments and determining whether existing treatments may be efficacious in broader populations of patients. The goal of most POC trials is to determine whether a treatment is likely to be efficacious for a given indication and thus whether it is worth investing the financial resources and participant exposure necessary for a confirmatory trial of that intervention. A challenge in designing POC trials is obtaining sufficient information to make this important go/no-go decision in a cost-effective manner. An IMMPACT consensus meeting was convened to discuss design considerations for POC trials in analgesia, with a focus on maximizing power with limited resources and participants. We present general design aspects to consider including patient population, active comparators and placebos, study power, pharmacokinetic-pharmacodynamic relationships, and minimization of missing data. Efficiency of single-dose studies for treatments with rapid onset is discussed. The trade-off between parallel-group and crossover designs with respect to overall sample sizes, trial duration, and applicability is summarized. The advantages and disadvantages of more recent trial designs, including N-of-1 designs, enriched designs, adaptive designs, and sequential parallel comparison designs, are summarized, and recommendations for consideration are provided. More attention to identifying efficient yet powerful designs for POC clinical trials of chronic pain treatments may increase the percentage of truly efficacious pain treatments that are advanced to confirmatory trials while decreasing the percentage of ineffective treatments that continue to be evaluated rather than abandoned.

Abuse liability measures for use in analgesic clinical trials in patients with pain: IMMPACT recommendations

Assessing and mitigating the abuse liability (AL) of analgesics is an urgent clinical and societal problem. Analgesics have traditionally been assessed in randomized clinical trials (RCTs) designed to demonstrate analgesic efficacy relative to placebo or an active comparator. In these trials, rigorous, prospectively designed assessment for AL is generally not performed. The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) convened a consensus meeting to review the available evidence and discuss methods for improving the assessment of the AL of analgesics in clinical trials in patients with pain. Recommendations for improved assessment include: (1) performing trials that include individuals with diverse risks of abuse; (2) improving the assessment of AL in clinical trials (eg, training study personnel in the principles of abuse and addiction behaviors, designing the trial to assess AL outcomes as primary or secondary outcome measures depending on the trial objectives); (3) performing standardized assessment of outcomes, including targeted observations by study personnel and using structured adverse events query forms that ask all subjects specifically for certain symptoms (such as euphoria and craving); and (4) collecting detailed information about events of potential concern (eg, unexpected urine drug testing results, loss of study medication, and dropping out of the trial). The authors also propose a research agenda for improving the assessment of AL in future trials.

Effect of variability in the 7-day baseline pain diary on the assay sensitivity of neuropathic pain randomized clinical trials: an ACTTION study

The degree of variability in the patient baseline 7-day diary of pain ratings has been hypothesized to have a potential effect on the assay sensitivity of randomized clinical trials of pain therapies. To address this issue, we obtained clinical trial data from the Food and Drug Administration (FDA) through the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership, and harmonized patient level data from 12 clinical trials (4 gabapentin and 8 pregabalin) in postherpetic neuralgia (PHN) and painful diabetic peripheral neuropathy (DPN). Models were developed using exploratory logistic regression to examine the interaction between available baseline factors and treatment (placebo vs active medication) in predicting patient response to therapy (ie, >30% improvement). Our analysis demonstrated an increased likelihood of response in the placebo-treated group for patients with a higher standard deviation in the baseline 7-day diary without affecting the likelihood of a response in the active medication-treated group, confirming our hypothesis. In addition, there was a small but significant age-by-treatment interaction in the PHN model, and small weight-by-treatment interaction in the DPN model. The patient's sex, baseline pain level, and the study protocol had an effect only on the likelihood of response overall. Our results suggest the possibility that, at least in some disease processes, excluding patients with a highly variable baseline 7-day diary has the potential to improve the assay sensitivity of these analgesic clinical trials, although reductions of external validity must be considered when increasing the homogeneity of the investigated sample.

Assessment of pain and activity using an electronic pain diary and actigraphy device in a randomized, placebo-controlled crossover trial of celecoxib in osteoarthritis of the knee

OBJECTIVE

The primary goal was to determine whether a composite measure of pain and activity is a more responsive assessment of analgesic effect than pain alone or activity alone in patients with osteoarthritis (OA) of the knee.

DESIGN

We conducted a randomized, double-blind, placebo-controlled, 2-period, crossover study of celecoxib vs. placebo in subjects with chronic pain due to knee OA. Patients with knee OA and baseline pain intensity score ≥4 on a 0-10 numerical rating scale (NRS) before each period were randomized. Pain endpoints included in-clinic pain score (24-hour and 1-week recall), daily paper diary pain score, current pain on an electronic pain diary (each on NRS), and WOMAC pain subscale. Activity measures included WOMAC function subscale and actigraphy using a device. Three composite pain-activity measures were prespecified.

RESULTS

Sixty-three patients were randomized and 47 completed the study. The WOMAC pain subscale was the most responsive of all five pain measures. Pain-activity composites resulted in a statistically significant difference between celecoxib and placebo but were not more responsive than pain measures alone. However, a composite responder defined as having 20% improvement in pain or 10% improvement in activity yielded much larger differences between celecoxib and placebo than with pain scores alone. Actigraphy was more responsive than the WOMAC function scale, possibly due to lower placebo responsiveness.

CONCLUSION

We have identified composite pain-activity measures that are similarly or more responsive than pain-alone measures in patients with OA. Further research is warranted to determine the optimal method for computing these composites.

Reporting of primary analyses and multiplicity adjustment in recent analgesic clinical trials: ACTTION systematic review and recommendations

Performing multiple analyses in clinical trials can inflate the probability of a type I error, or the chance of falsely concluding a significant effect of the treatment. Strategies to minimize type I error probability include prespecification of primary analyses and statistical adjustment for multiple comparisons, when applicable. The objective of this study was to assess the quality of primary analysis reporting and frequency of multiplicity adjustment in 3 major pain journals (ie, European Journal of Pain, Journal of Pain, and PAIN®). A total of 161 randomized controlled trials investigating noninvasive pharmacological treatments or interventional treatments for pain, published between 2006 and 2012, were included. Only 52% of trials identified a primary analysis, and only 10% of trials reported prespecification of that analysis. Among the 33 articles that identified a primary analysis with multiple testing, 15 (45%) adjusted for multiplicity; of those 15, only 2 (13%) reported prespecification of the adjustment methodology. Trials in clinical pain conditions and industry-sponsored trials identified a primary analysis more often than trials in experimental pain models and non-industry-sponsored trials, respectively. The results of this systematic review demonstrate deficiencies in the reporting and possibly the execution of primary analyses in published analgesic trials. These deficiencies can be rectified by changes in, or better enforcement of, journal policies pertaining to requirements for the reporting of analyses of clinical trial data.

Classification and definition of misuse, abuse, and related events in clinical trials: ACTTION systematic review and recommendations

As the nontherapeutic use of prescription medications escalates, serious associated consequences have also increased. This makes it essential to estimate misuse, abuse, and related events (MAREs) in the development and postmarketing adverse event surveillance and monitoring of prescription drugs accurately. However, classifications and definitions to describe prescription drug MAREs differ depending on the purpose of the classification system, may apply to single events or ongoing patterns of inappropriate use, and are not standardized or systematically employed, thereby complicating the ability to assess MARE occurrence adequately. In a systematic review of existing prescription drug MARE terminology and definitions from consensus efforts, review articles, and major institutions and agencies, MARE terms were often defined inconsistently or idiosyncratically, or had definitions that overlapped with other MARE terms. The Analgesic, Anesthetic, and Addiction Clinical Trials, Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership convened an expert panel to develop mutually exclusive and exhaustive consensus classifications and definitions of MAREs occurring in clinical trials of analgesic medications to increase accuracy and consistency in characterizing their occurrence and prevalence in clinical trials. The proposed ACTTION classifications and definitions are designed as a first step in a system to adjudicate MAREs that occur in analgesic clinical trials and postmarketing adverse event surveillance and monitoring, which can be used in conjunction with other methods of assessing a treatment's abuse potential.

Assay sensitivity and study features in neuropathic pain trials: an ACTTION meta-analysis

OBJECTIVE

Our objective was to identify patient, study, and site factors associated with assay sensitivity in placebo-controlled neuropathic pain trials.

METHODS

We examined the associations between study characteristics and standardized effect size (SES) in a database of 200 publicly available randomized clinical trials of pharmacologic treatments for neuropathic pain.

RESULTS

There was considerable heterogeneity in the SESs among the examined trials. Univariate meta-regression analyses indicated that larger SESs were significantly associated with trials that had 1) greater minimum baseline pain inclusion criteria, 2) greater mean subject age, 3) a larger percentage of Caucasian subjects, and 4) a smaller total number of subjects. In a multiple meta-regression analysis, the associations between SES and minimum baseline pain inclusion criterion and age remained significant.

CONCLUSIONS

Our analyses have examined potentially modifiable correlates of study SES and shown that a minimum pain inclusion criterion of 40 or above on a 0 to 100 scale is associated with a larger SES. These data provide a foundation for investigating strategies to improve assay sensitivity and thereby decrease the likelihood of falsely negative outcomes in clinical trials of efficacious treatments for neuropathic pain.

Adverse event assessment, analysis, and reporting in recent published analgesic clinical trials: ACTTION systematic review and recommendations

The development of valid and informative treatment risk-benefit profiles requires consistent and thorough information about adverse event (AE) assessment and participants' AEs during randomized controlled trials (RCTs). Despite a 2004 extension of the Consolidated Standards of Reporting Trials (CONSORT) statement recommending the specific AE information that investigators should report, there is little evidence that analgesic RCTs adequately adhere to these recommendations. This systematic review builds on prior recommendations by describing a comprehensive checklist for AE reporting developed to capture clinically important AE information. Using this checklist, we coded AE assessment methods and reporting in all 80 double-blind RCTs of noninvasive pharmacologic treatments published in the European Journal of Pain, Journal of Pain, and PAIN® from 2006 to 2011. Across all trials, reports of AEs were frequently incomplete, inconsistent across trials, and, in some cases, missing. For example, >40% of trials failed to report any information on serious adverse events. Trials of participants with acute or chronic pain conditions and industry-sponsored trials typically provided more and better-quality AE data than trials involving pain-free volunteers or trials that were not industry sponsored. The results of this review suggest that improved AE reporting is needed in analgesic RCTs. We developed an ACTTION (Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks) AE reporting checklist that is intended to assist investigators in thoroughly and consistently capturing and reporting these critically important data in publications.

Prescription opioid abuse: challenges and opportunities for payers

OBJECTIVES

Prescription opioid abuse and addiction are serious problems with growing societal and medical costs, resulting in billions of dollars of excess costs to private and governmental health insurers annually. Although difficult to accurately assess, prescription opioid abuse also leads to increased insurance costs in the form of property and liability claims, and costs to state and local governments for judicial, emergency, and social services. This manuscript's objective is to provide payers with strategies to control these costs, while supporting safe use of prescription opioid medications for patients with chronic pain.

METHOD

A Tufts Health Care Institute Program on Opioid Risk Management meeting was convened in June 2010 with private and public payer representatives, public health and law enforcement officials, pain specialists, and other stakeholders to present research and develop recommendations on solutions that payers might implement to combat this problem.

RESULTS

While protecting access to prescription opioids for patients with pain, private and public payers can implement strategies to mitigate financial risks associated with opioid abuse, using internal strategies such as formulary controls, claims data surveillance, and claims matching; and external policies and procedures that support and educate physicians on reducing opioid risks among patients with chronic pain.

CONCLUSIONS

Reimbursement policies, incentives, and health technology systems that encourage physicians to use universal precautions, to consult prescription monitoring program (PMP) data, and to implement Screening, Brief Intervention, and Referral to Treatment protocols have a high potential to reduce insurer risks while addressing a serious public health problem.

Core outcome measures for opioid abuse liability laboratory assessment studies in humans: IMMPACT recommendations

A critical component in development of opioid analgesics is assessment of their abuse liability (AL). Standardization of approaches and measures used in assessing AL have the potential to facilitate comparisons across studies, research laboratories, and drugs. The goal of this report is to provide consensus recommendations regarding core outcome measures for assessing the abuse potential of opioid medications in humans in a controlled laboratory setting. Although many of the recommended measures are appropriate for assessing the AL of medications from other drug classes, the focus here is on opioid medications because they present unique risks from both physiological (e.g., respiratory depression, physical dependence) and public health (e.g., individuals in pain) perspectives. A brief historical perspective on AL testing is provided, and those measures that can be considered primary and secondary outcomes and possible additional outcomes in AL assessment are then discussed. These outcome measures include the following: subjective effects (some of which comprise the primary outcome measures, including drug liking; physiological responses; drug self-administration behavior; and cognitive and psychomotor performance. Before presenting recommendations for standardized approaches and measures to be used in AL assessments, the appropriateness of using these measures in clinical trials with patients in pain is discussed.

Research design considerations for clinical studies of abuse-deterrent opioid analgesics: IMMPACT recommendations

Opioids are essential to the management of pain in many patients, but they also are associated with potential risks for abuse, overdose, and diversion. A number of efforts have been devoted to the development of abuse-deterrent formulations of opioids to reduce these risks. This article summarizes a consensus meeting that was organized to propose recommendations for the types of clinical studies that can be used to assess the abuse deterrence of different opioid formulations. Because of the many types of individuals who may be exposed to opioids, an opioid formulation will need to be studied in several populations using various study designs to determine its abuse-deterrent capabilities. It is recommended that the research conducted to evaluate abuse deterrence should include studies assessing: (1) abuse liability, (2) the likelihood that opioid abusers will find methods to circumvent the deterrent properties of the formulation, (3) measures of misuse and abuse in randomized clinical trials involving pain patients with both low risk and high risk of abuse, and (4) postmarketing epidemiological studies.

The measurement of symptoms and side effects in clinical trials of chronic pain

Clinical trials in chronic pain have used various methods to assess the effect of medications. In addition to measuring symptom relief, researchers must also address adverse events (AEs) associated with the medication to evaluate overall therapeutic results. This paper reviews methods of measuring symptoms and AEs, including passive capture, scripted prompting, prospective assessments of side effects of interest, and prospective comprehensive symptom checklists. Methods of measuring therapeutic results have advantages and disadvantages. Although passive AE capture (unscripted, open-ended questions about symptoms) is not constrained by preconceptions of potential AEs, it sometimes fails to capture clinically significant AEs. Scripted prompting (prespecified, scripted, open-ended questions about symptoms) is likely to address the latter problem but preclude consistency across trials. Prospective assessments (prespecified symptom inventories) can offer greater sensitivity and consistency in detecting side effects of specific treatments. Comprehensive symptom distress inventories can be more sensitive measures of overall treatment benefit, which may be important when efficacy, passive AE capture, and comprehensive quality of life (QOL) batteries fail to differentiate between treatments. In cancer populations these inventories have been statistically correlated with survival and other important clinical outcomes, even after controlling for disease status, global QOL, psychological state, and performance status. Other important considerations are patient perceptions of the importance of symptoms, the correlations between QOL and symptom distress, and the usefulness of global ratings, in which patients integrate any perceived benefits of the medication with tolerability and other factors, such as convenience and cost.

Considerations for improving assay sensitivity in chronic pain clinical trials: IMMPACT recommendations

A number of pharmacologic treatments examined in recent randomized clinical trials (RCTs) have failed to show statistically significant superiority to placebo in conditions in which their efficacy had previously been demonstrated. Assuming the validity of previous evidence of efficacy and the comparability of the patients and outcome measures in these studies, such results may be a consequence of limitations in the ability of these RCTs to demonstrate the benefits of efficacious analgesic treatments vs placebo ("assay sensitivity"). Efforts to improve the assay sensitivity of analgesic trials could reduce the rate of falsely negative trials of efficacious medications and improve the efficiency of analgesic drug development. Therefore, an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting was convened in which the assay sensitivity of chronic pain trials was reviewed and discussed. On the basis of this meeting and subsequent discussions, the authors recommend consideration of a number of patient, study design, study site, and outcome measurement factors that have the potential to affect the assay sensitivity of RCTs of chronic pain treatments. Increased attention to and research on methodological aspects of clinical trials and their relationships with assay sensitivity have the potential to provide the foundation for an evidence-based approach to the design of analgesic clinical trials and expedite the identification of analgesic treatments with improved efficacy and safety.

Determining the clinically important difference in visual analog scale scores in abuse liability studies evaluating novel opioid formulations

PURPOSE

This study determined how the magnitude of change in positive subjective responses predicts clinical outcome in a treatment setting. Specifically, we attempted to define what constitutes a clinically important difference (CID) in subjective responses.

METHODS

A 100-mm visual analog scale (VAS) measured subjective ratings of drug "high," calculated via an anchor-based method with published data from participants receiving sustained-release naltrexone (NTX) and heroin in a laboratory setting. The data were then compared to clinical outcomes in a treatment trial with sustained-release naltrexone. A distribution-based method subsequently analyzed data from participants who received ALO-01 (extended-release morphine with sequestered NTX) to predict its abuse liability.

RESULTS

Differences in ratings of drug high of approximately 10 mm on a 100-mm line were clinically significant. By extrapolation, CIDs were also found between crushed or intact ALO-01 and immediate-release morphine sulfate (IRMS). No CIDs were found between intact and crushed ALO-01.

CONCLUSIONS

From laboratory and treatment trial data involving naltrexone, calculation of CIDs in subjective ratings of high is possible. Consequently, crushing/swallowing or injecting ALO-01 produces clinically significantly less drug high than oral or intravenous morphine alone, suggesting that ALO-01 has lower abuse liability by those routes than morphine formulations.

Outcome measures in placebo-controlled trials of osteoarthritis: responsiveness to treatment effects in the REPORT database

INTRODUCTION

Treatment response in randomized clinical trials (RCT) of osteoarthritis (OA) has been assessed by multiple primary and secondary outcomes, including pain, function, patient and clinician global measures of status and response to treatment, and various composite and responder measures. Identifying outcome measures with greater responsiveness to treatment is important to increase the assay sensitivity of RCTs.

OBJECTIVE

To assess and compare the responsiveness of different outcome measures used in placebo-controlled RCTs of OA.

SEARCH STRATEGY

The Resource for Evaluating Procedures and Outcomes of Randomized Trials database includes placebo-controlled clinical trials of pharmacologic treatments (oral, topical, or transdermal) for OA identified from a systematic literature search of RCTs published or publicly available before August 5, 2009, which was conducted using PubMed, the Cochrane collaboration, publicly-available websites, and reference lists of retrieved publications.

DATA COLLECTION AND ANALYSIS

Data collected included: (1) pain assessed with single-item ratings and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale; (2) patient and clinician global measures of status, improvement, and treatment response; (3) function assessed by the WOMAC function subscale; (4) stiffness assessed by the WOMAC stiffness subscale; and (5) the WOMAC and Lequesne Algofunctional Index composite outcomes. Measures were grouped according to the total number of response categories (i.e., <10 categories or ≥10 categories). The treatment effect (difference in mean change from baseline between the placebo and active therapy arms) and standardized effect size (SES) were estimated for each measure in a meta-analysis using a random effects model.

RESULTS

There were 125 RCTs with data to compute the treatment effect for at least one measure; the majority evaluated non-steroidal anti-inflammatory drugs (NSAIDs), followed by opioids, glucosamine and/or chondroitin, and acetaminophen. In general, the patient-reported pain outcome measures had comparable responsiveness to treatment as shown by the estimates of treatment effects and SES. Treatment effects and SESs were generally higher for patient-reported global measures compared with clinician-rated global measures but generally similar for the WOMAC and Lequesne composite measures.

CONCLUSIONS

Comparing different outcome measures using meta-analysis and selecting those that have the greatest ability to identify efficacious treatments may increase the efficiency of clinical trials of treatments for OA. Improvements in the quality of the reporting of clinical trial results are needed to facilitate meta-analyses to evaluate the responsiveness of outcome measures and to also address other issues related to assay sensitivity.

Prescribing recommendations for the treatment of acute pain in dentistry

Effective acute pain management is an essential but sometimes challenging component of dental practice. Numerous studies have examined the efficacy of various analgesic agents in dental postoperative models. This article combines an evaluation of the available evidence with current prescribing patterns to provide dental practitioners prescribing recommendations for acute pain, based on the anticipated severity of post-procedural pain. An important consideration when prescribing analgesics is to determine for whom opioid analgesics are necessary and appropriate, and if so, the dose and quantity that should be prescribed. This is partly because of the prevalence of substance and alcohol abuse that can be expected to be encountered within the dental patient population, and because substance abusers in the community frequently obtain prescription drugs from friends and family for misuse.

Volume of prescription opioids used nonmedically in the United States

ABSTRACT To understand the magnitude of prescription opioid abuse in the United States, it is critical to determine how many dosage units of prescription opioids are ingested nonmedically per year. Using several public and private databases, the authors estimated that in 2002-2003, among the 10.89 million individuals projected to have used prescription opioids nonmedically, a minimum of 430.61 million doses were used nonmedically per year (assuming only one dose consumed per nonmedical use per day per individual). This represented about 1/25 of all prescription opioid doses dispensed. This estimate provides a perspective on the magnitude of prescription opioids abuse and should help policy makers enact policies that reduce prescription opioid abuse and diversion without preventing legitimate access to opioid therapy.

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

There has been an increase in the number of chronic pain clinical trials in which the treatments being evaluated did not differ significantly from placebo in the primary efficacy analyses despite previous research suggesting that efficacy could be expected. These findings could reflect a true lack of efficacy or methodological and other aspects of these trials that compromise the demonstration of efficacy. There is substantial variability among chronic pain clinical trials with respect to important research design considerations, and identifying and addressing any methodological weaknesses would enhance the likelihood of demonstrating the analgesic effects of new interventions. An IMMPACT consensus meeting was therefore convened to identify the critical research design considerations for confirmatory chronic pain trials and to make recommendations for their conduct. We present recommendations for the major components of confirmatory chronic pain clinical trials, including participant selection, trial phases and duration, treatment groups and dosing regimens, and types of trials. Increased attention to and research on the methodological aspects of confirmatory chronic pain clinical trials has the potential to enhance their assay sensitivity and ultimately provide more meaningful evaluations of treatments for chronic pain.