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.

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.

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.

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

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

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.

Evaluation of the Relative Intranasal Abuse Potential of a Hydrocodone Extended-Release Tablet Formulated with Abuse-Deterrence Technology in Nondependent, Recreational Opioid Users.

Objective: To assess the intranasal abuse potential of hydrocodone extended-release (ER) tablets developed with CIMA Abuse-Deterrence Technology compared with hydrocodone powder and hydrocodone bitartrate ER capsules (Zohydro ER, original formulation [HYD-OF]). Design: Single-dose, randomized, double-blind, quadruple-dummy, active- and placebo-controlled, crossover study. Setting: One US site. Subjects: Healthy, adult, nondependent, recreational opioid users. Methods: Subjects able to tolerate intranasal hydrocodone and discriminate hydrocodone from placebo were eligible for study enrollment. Eligible participants randomly received intranasal hydrocodone ER, intranasal hydrocodone powder, intranasal HYD-OF, intact oral hydrocodone ER, and placebo. Coprimary pharmacodynamic end points were a maximum effect on "at the moment" Drug Liking visual analog scale and Overall Drug Liking visual analog scale. Pharmacokinetics and safety were assessed. Results: Mean maximum effect for "at the moment" Drug Liking was significantly (P < 0.01) lower for intranasal hydrocodone ER (72.8) compared with hydrocodone powder (80.2) and HYD-OF (83.2). Similar results were observed for Overall Drug Liking maximum effect (68.5 vs 77.1 and 79.8, respectively; P < 0.01). Secondary end points, including balance of effects and positive, sedative, and other effects, were consistent with these results. Intranasal treatments showed significantly greater effects vs placebo, while intact oral hydrocodone ER was similar to placebo. For each treatment, plasma concentration-time profiles paralleled "at the moment" Drug Liking over time. Incidences of adverse events for intranasal treatments were 52% for hydrocodone ER, 53% for hydrocodone powder, and 61% for HYD-OF. Conclusions: The statistically significant differences between hydrocodone ER vs hydrocodone powder and HYD-OF for the primary drug liking end points indicate a lower intranasal abuse potential with hydrocodone ER in healthy, nondependent, recreational opioid users.

Effect of Food on the Pharmacokinetics of Single- and Multiple-Dose Hydrocodone Extended Release in Healthy Subjects.

BACKGROUND AND OBJECTIVES: Food intake can alter the pharmacokinetics of certain medications, including changes in their oral bioavailability, which is of particular concern for extended-release (ER) opioids because of the high drug loads. Two randomized, open-label studies assessed the effect of food on the pharmacokinetics of single and multiple doses of hydrocodone ER formulated with CIMA® Abuse-Deterrence Technology. METHODS: Healthy subjects in fed and fasted states received single 90-mg doses of hydrocodone ER (Studies 1 and 2) or multiple doses of hydrocodone ER (45 mg twice daily on days 2-3, 60 mg twice daily on days 4-5, 90 mg twice daily on days 6-10, and 90 mg once in the morning on day 11) (Study 2). Naltrexone was administered to minimize opioid-related adverse events. Pharmacokinetic parameters included maximum hydrocodone plasma concentration (C max) and area under the concentration-versus-time curve from time 0 to infinity (AUC0-∞) in Study 1 (day 1) and for one dosing interval at steady state (AUCτ,ss) in Study 2 (day 11). Before conducting the multiple-dose study, single-dose data were fitted with a population pharmacokinetic methodology. RESULTS: In total, 40 subjects were randomized to Study 1 and 43 subjects were randomized to Study 2. While overall exposure (AUC0-∞) was relatively similar (least squares mean ratio [90% CI]: 1.11 [1.06-1.16]), results indicated that the single-dose C max was 40% higher under fed versus fasted conditions (least squares mean ratio [90% CI]: 1.40 [1.31-1.51]; Study 1). Modeling of single-dose data predicted that the effect of food would be much less at steady state [predicted fed:fasted C max at steady state (C max,ss) and AUCτ,ss ratios of 1.18 and 1.09, respectively]. The multiple-dose study results validated these predicted ratios and indicated that the steady-state 90% CIs were within 0.80-1.25 for the fed:fasted C max,ss (1.14 [1.07-1.21]) and AUCτ,ss (1.11 [1.04-1.17]) parameters, indicating that clinically meaningful food effects at steady state are not expected. CONCLUSION: No evidence of an effect of food was found on the pharmacokinetics of hydrocodone ER after multiple days of twice-daily dosing.

Safety and Efficacy of a Topical Sodium Channel Inhibitor (TV-45070) in Patients With Postherpetic Neuralgia (PHN): A Randomized, Controlled, Proof-of-Concept, Crossover Study, With a Subgroup Analysis of the Nav1.7 R1150W Genotype.

OBJECTIVE: The objective was to evaluate the safety and efficacy of TV-45070 ointment, as a treatment for postherpetic neuralgia, and to explore the response in patients with the Nav1.7 R1150W gain-of-function polymorphism. MATERIALS AND METHODS: This was a randomized, placebo-controlled, 2-period, 2-treatment crossover trial. Patients with postherpetic neuralgia with moderate or greater pain received TV-45070 and placebo ointments, each applied twice daily for 3 weeks. The primary efficacy measure was the difference in change in mean daily pain score from baseline compared with the last week of placebo and active treatment. Secondary endpoints included responder rate analyses and a further exploratory analysis of response in carriers of the Nav1.7 R1150W polymorphism was conducted. RESULTS: Seventy patients were enrolled and 54 completed the study. TV-45070 was safe and well tolerated. No statistical difference was observed between treatments for the primary endpoint. However, the proportion of patients with ≥50% reduction in mean pain scores at week 3 was greater on TV-45070 than on placebo (26.8% vs. 10.7%, P=0.0039). Similarly, a greater proportion of patients on TV-45070 had a ≥30% reduction in mean pain scores at week 3 (39.3% on TV-45070 vs. 23.2% on placebo, P=0.0784). Of note, 63% of patients with the R1150W polymorphism versus 35% of wild-type carriers had a ≥30% reduction in mean pain score on TV-45070 at week 3 (no inferential analysis performed). CONCLUSIONS: The 50% responder analysis suggests a subpopulation may exist with a more marked analgesic response to TV-45070.The trend toward a larger proportion of responders within Nav1.7 R1150W carriers warrants further investigation.

Evaluation of Quality of Life, Functioning, Disability, and Work/School Productivity Following Treatment with an Extended-Release Hydrocodone Tablet Formulated with Abuse-Deterrence Technology: A 12-month Open-label Study in Patients with Chronic Pain.

BACKGROUND: This phase 3 study evaluated quality of life, functioning, and productivity after treatment with extended-release (ER) hydrocodone formulated with CIMA® Abuse-Deterrence Technology platform. METHODS: Patients with chronic pain were rolled over from a 12-week placebo-controlled hydrocodone ER study or were newly enrolled. Hydrocodone ER doses were titrated (15 to 90 mg every 12 hours) to an analgesic dose, and patients received up to 52 weeks of open-label treatment. Assessments included Clinician Assessment of Patient Function (CAPF), Patient Assessment of Function (PAF), Brief Pain Inventory-Short Form (BPI-SF), 36-item Short-Form Health Survey (SF-36), Sheehan Disability Scale (SDS), and World Health Organization Health and Work Performance Questionnaire-Short Form (HPQ-SF). RESULTS: Of 330 enrolled patients, 291 composed the full analysis population. By week 4, ≥ 50% of patients showed improvement from baseline in all 5 CAPF domains (general activities, walking, work/daily living, relationships, and enjoyment of life) and 6 of 7 PAF domains (work attendance, work performance, walking, exercise, socializing, and enjoying life). Mean decreases from baseline of 2 to 3 points were noted for BPI-SF pain interference questions from week 4 through endpoint. Mean improvements from baseline to endpoint in SF-36 subscales ranged from 3.3 to 22.3, and SDS scores improved from moderate (4.8 to 5.1) to mild (2.5 to 2.8) disruptions in work/school, social life, and family life. At endpoint, mean HPQ-SF absolute absenteeism scores decreased from 13.6 to 10.0 hours lost/month and absolute presenteeism scores improved from 67.0 to 77.1. CONCLUSIONS: Patients receiving hydrocodone ER showed early numeric improvements in functioning that continued throughout this 12-month study.

Participant Preferences for Pharmacologic Chronic Pain Treatment Trial Characteristics: An ACTTION Adaptive Choice-Based Conjoint Study.

Barriers to clinical trial recruitment can delay study completion, potentially resulting in increased costs and an unrepresentative sample. In the current study of 150 participants with chronic pain, we used a computerized adaptive choice-based conjoint survey that included 8 characteristics that may affect enrollment in pharmacologic pain treatment trials (ie, treatment allocation, frequency of pain ratings, treatment administration method, current medications, number of study visits, availability of evening and weekend visits, invasiveness of laboratory procedures, payment). These data were analyzed using Sawtooth Software ver. 8.4.8 (Sawtooth Software, Inc, Orem, UT), which identifies the characteristics that dominate participants' decisions across multiple sets of potential trials. Three characteristics had the largest relative importance in participants' trial preferences: 1) invasiveness of required laboratory procedures (ie, 22%), with no procedures or blood tests preferred over ice-water sensory testing or skin biopsy; 2) ability to continue current pain medications (21%); and 3) payment for study participation (21%), with higher payment preferred. The fourth most important characteristic was number of study visits (13%), with participants preferring fewer in-person visits and more phone contacts. Understanding the preferences of potential participants is an important step toward enhancing enrollment in pain treatment trials. PERSPECTIVE: This article presents the preferences of individuals with chronic pain conditions regarding modifiable pain treatment trial characteristics (eg, number of study visits, payment, treatment allocation). These findings may help to improve enrollment into analgesic clinical trials and in turn accelerate the development of new pain treatments.

Six-month, open-label study of hydrocodone extended release formulated with abuse-deterrence technology: Safety, maintenance of analgesia, and abuse potential.

OBJECTIVE: To evaluate long-term safety, maintenance of analgesia, and aberrant drug-related behaviors of hydrocodone extended release (ER) formulated with CIMA® Abuse-Deterrence Technology. DESIGN: Phase 3, multicenter, open-label extension. SETTING: Fifty-six US centers. PATIENTS: Adults with chronic low back pain completing a 12-week placebocontrolled study of abuse-deterrent hydrocodone ER were eligible. One hundred eighty-two patients enrolled and received ≥1 dose of study drug, 170 entered openlabel treatment, and 136 completed the study. INTERVENTIONS: Patients receiving hydrocodone ER in the 12-week, placebo-controlled study continued their previous dose unless adjustment was needed; those previously receiving placebo (n=78) underwent dose titration/adjustment to an analgesic dose (15-90 mg every 12 hours). Patients received 22 weeks of open-label treatment. SAFETY: adverse events (AEs). Maintenance of analgesia: worst pain intensity (WPI) and average pain intensity (API) at each study visit. Aberrant drug behavior: study drug loss and diversion. RESULTS: AEs were reported for 65/182 (36 percent) patients during dose titration/ adjustment and 88/170 (52 percent) during open-label treatment. No treatmentrelated serious AEs were reported. There were no clinically meaningful trends in other safety assessments, including physical examinations and pure tone audiometry. One patient receiving hydrocodone ER 30 mg twice daily experienced a severe AE of neurosensory deafness that was considered treatment related. Mean WPI and API remained steady throughout open-label treatment. Six (3 percent) patients reported medication loss, and 5 (3 percent) reported diversion. CONCLUSIONS: Abuse-deterrent hydrocodone ER was generally well tolerated in patients with chronic low back pain, maintained efficacy, and was associated with low rates of loss and diversion.

Assessment of physical function and participation in chronic pain clinical trials: IMMPACT/OMERACT recommendations.

Although pain reduction is commonly the primary outcome in chronic pain clinical trials, physical functioning is also important. A challenge in designing chronic pain trials to determine efficacy and effectiveness of therapies is obtaining appropriate information about the impact of an intervention on physical function. The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) and Outcome Measures in Rheumatology (OMERACT) convened a meeting to consider assessment of physical functioning and participation in research on chronic pain. The primary purpose of this article is to synthesize evidence on the scope of physical functioning to inform work on refining physical function outcome measurement. We address issues in assessing this broad construct and provide examples of frequently used measures of relevant concepts. Investigators can assess physical functioning using patient-reported outcome (PRO), performance-based, and objective measures of activity. This article aims to provide support for the use of these measures, covering broad aspects of functioning, including work participation, social participation, and caregiver burden, which researchers should consider when designing chronic pain clinical trials. Investigators should consider the inclusion of both PROs and performance-based measures as they provide different but also important complementary information. The development and use of reliable and valid PROs and performance-based measures of physical functioning may expedite development of treatments, and standardization of these measures has the potential to facilitate comparison across studies. We provide recommendations regarding important domains to stimulate research to develop tools that are more robust, address consistency and standardization, and engage patients early in tool development.

Abuse-deterrent formulations of prescription opioid analgesics in the management of chronic noncancer pain.

Misuse, abuse and diversion of prescription opioid analgesics represent a global public health concern. The development of abuse-deterrent formulations (ADFs) of prescription opioid analgesics is an important step toward reducing abuse and diversion of these medications, as well as potentially limiting medical consequences when misused or administered in error. ADFs aim to hinder extraction of the active ingredient, prevent administration through alternative routes and/or make abuse of the manipulated product less attractive, less rewarding or aversive. However, opioid ADFs may still be abused via the intended route of administration by increasing the dose and/or dosing frequency. The science of abuse deterrence and the regulatory landscape are still relatively new and evolving. This paper reviews the current status of opioid ADFs, with particular focus on different approaches that can be used to deter abuse, regulatory considerations and implications for clinical management.

Routes of abuse of prescription opioid analgesics: a review and assessment of the potential impact of abuse-deterrent formulations.

Prescription opioid analgesics are an important treatment option for patients with chronic pain; however, misuse, abuse and diversion of these medications are a major global public health concern. Prescription opioid analgesics can be abused via intended and non-intended routes of administration, both intact or after manipulation of the original formulation to alter the drug-delivery characteristics. Available data indicate that ingestion (with or without manipulation of the prescribed formulation) is the most prevalent route of abuse, followed by inhalation (snorting, smoking and vaping) and injection. However, reported routes of abuse vary considerably between different formulations. A number of factors have been identified that appear to be associated with non-oral routes of abuse, including a longer duration of abuse, younger age, male sex and a rural or socially deprived location. The development of abuse-deterrent formulations of prescription opioid analgesics is an important step toward reducing abuse of these medications. Available abuse-deterrent formulations aim to hinder extraction of the active ingredient, prevent administration through alternative routes and/or make abuse of the manipulated product less attractive, less rewarding or even aversive. There are currently five opioid analgesics with a Food and Drug Administration abuse-deterrent label, and a number of other products are under review. A growing body of evidence suggests that introduction of abuse-deterrent opioid analgesics in the USA has been associated with decreased rates of abuse of these formulations. The availability of abuse-deterrent formulations therefore appears to represent an important step toward curbing the epidemic of abuse of prescription opioid analgesics, while ensuring the availability of effective pain medications for patients with legitimate medical need.

Twelve-month, open-label assessment of long-term safety and abuse potential of hydrocodone extended-release formulated with abuse-deterrence technology in patients with chronic pain.

OBJECTIVE: To evaluate long-term safety of hydrocodone extended-release (ER) formulated with CIMA(®) Abuse-Deterrence Technology platform. DESIGN: Phase 3, open-label study. SETTING: Sixty-one US study centers. PATIENTS: Patients with chronic pain newly enrolled or rolled over from a 12-week, placebo-controlled hydrocodone ER study; 330 patients enrolled, 329 patients received study drug, and 189 completed the study. INTERVENTION: After titrating to an analgesic dose (15-90 mg every 12 hours), patients received ≤ 52 weeks of open-label treatment. SAFETY: adverse events (AEs), vital signs, laboratory values, electrocardiograms, and audiometry. Abuse potential: drug loss and diversion, Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R), Addiction Behaviors Checklist (ABC), Current Opioid Misuse Measure (COMM) questionnaires, and Patient Global Assessment (PGA) of pain control. RESULTS: Of 329 patients who received ≥ 1 hydrocodone ER dose, 284 (86 percent) reported ≥ 1 AE and 27 (8 percent) experienced ≥ 1 serious AE. Sixty-two (19 percent) patients withdrew because of AEs, and two AEs leading to death were reported. No serious AEs or AEs leading to death were considered treatment related by the investigator. There were no clinically meaningful trends in other safety assessments. SOAPP-R, ABC, and COMM scores demonstrated low risk of aberrant drug-related behavior. Good/excellent PGA responses were reported by 20 percent of patients at baseline and 75 percent at endpoint. The incidence of drug loss (11 percent) and diversion (2 percent) was low. CONCLUSIONS: Hydrocodone ER demonstrated acceptable safety when administered for ≤ 12 months in patients with chronic pain. Low occurrence of aberrant drugrelated behavior may support the abuse-deterrence properties of hydrocodone ER.

Efficacy and tolerability of a hydrocodone extended-release tablet formulated with abuse-deterrence technology for the treatment of moderate-to-severe chronic pain in patients with osteoarthritis or low back pain.

This double-blind, placebo-controlled study evaluated the efficacy and safety of hydrocodone extended release (ER) developed with abuse-deterrence technology to provide sustained pain relief and limit effects of alcohol and tablet manipulation on drug release. Eligible patients with chronic moderate-to-severe low back or osteoarthritis pain were titrated to an analgesic dose of hydrocodone ER (15-90 mg) and randomized to placebo or hydrocodone ER every 12 hours. The primary efficacy measure was change from baseline to week 12 in weekly average pain intensity (API; 0=no pain, 10=worst pain imaginable). Secondary measures included percentage of patients with >33% and >50% increases from baseline in weekly API, change from baseline in weekly worst pain intensity, supplemental opioid usage, aberrant drug-use behaviors, and adverse events. Overall, 294 patients were randomized and received ≥1 dose of placebo (n=148) or hydrocodone ER (n=146). Weekly API did not differ significantly between hydrocodone ER and placebo at week 12 (P=0.134); although, in post hoc analyses, the change in weekly API was significantly lower with hydrocodone ER when excluding the lowest dose (15 mg; least squares mean, -0.20 vs 0.40; P=0.032). Significantly more patients had >33% and >50% increase in weekly API with placebo (P<0.05), and mean weekly worst pain intensity was significantly lower with hydrocodone ER at week 12 (P=0.026). Supplemental medication usage was higher with placebo (86%) than hydrocodone ER (79%). Incidence of aberrant drug-use behaviors was low, and adverse events were similar between groups. This study did not meet the primary endpoint, although results support the effectiveness of this hydrocodone ER formulation in managing chronic low back or osteoarthritis pain. Use of the hydrocodone ER 15-mg dose, a robust placebo response, and use of supplemental analgesics, particularly in the placebo group, may have limited detection of a statistically significant treatment effect, and additional research is needed to clarify these findings.

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

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

Efficacy and safety of a hydrocodone extended-release tablet formulated with abuse-deterrence technology in patients with moderate-to-severe chronic low back pain.

OBJECTIVE: To evaluate efficacy and safety of hydrocodone bitartrate extended release (ER) tablets developed with CIMA(®) Abuse-Deterrence Technology (ADT) versus placebo in alleviating moderate-to-severe pain in patients with chronic low back pain. DESIGN: Phase 3, randomized, double-blind study consisting of a screening period (7-14 days), open-label titration period (≤ 6 weeks), and double-blind treatment period (≤ 12 weeks). SETTING: Seventy-eight US centers. MAIN OUTCOME MEASURES: Changes from baseline at week 12 in weekly average of daily worst pain intensity (WPI; primary efficacy measure), weekly average pain intensity (API; secondary efficacy measure), adverse events (AEs), and study drug loss and diversion. RESULTS: Patients (N = 625) who entered open-label dose titration and identified the analgesic hydrocodone ER dose (30-90 mg every 12 h) providing optimal pain relief with minimal AEs were randomized to hydrocodone ER (n = 191) or placebo (n = 180) for double-blind treatment at the identified dose; 297 patients completed the study. Least squares means [SE] changes from baseline were significantly greater (worsening pain; 11-point scale) with placebo than hydrocodone ER in weekly average of daily WPI (0.74 [0.15] vs 0.11 [0.14]; p < 0.001) and weekly API (0.55 [0.14] vs -0.03 [0.12]; p < 0.001). The most common AEs with hydrocodone ER were constipation (14 percent) and nausea (10 percent). Study drug loss (≤ 4 percent) and diversion (≤ 2 percent) rates were low. CONCLUSIONS: Hydrocodone ER formulated with ADT was significantly more effective than placebo in alleviating chronic low back pain and demonstrated a safety profile consistent with that of opioids, with a low occurrence of study drug loss and diversion.

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.