Warren Wen

Patient phenotyping in clinical trials of chronic pain treatments: IMMPACT recommendations.

Abstract There is tremendous interpatient variability in the response to analgesic therapy (even for efficacious treatments), which can be the source of great frustration in clinical practice. This has led to calls for “precision medicine” or personalized pain therapeutics (ie, empirically based algorithms that determine the optimal treatments, or treatment combinations, for individual patients) that would presumably improve both the clinical care of patients with pain and the success rates for putative analgesic drugs in phase 2 and 3 clinical trials. However, before implementing this approach, the characteristics of individual patients or subgroups of patients that increase or decrease the response to a specific treatment need to be identified. The challenge is to identify the measurable phenotypic characteristics of patients that are most predictive of individual variation in analgesic treatment outcomes, and the measurement tools that are best suited to evaluate these characteristics. In this article, we present evidence on the most promising of these phenotypic characteristics for use in future research, including psychosocial factors, symptom characteristics, sleep patterns, responses to noxious stimulation, endogenous pain-modulatory processes, and response to pharmacologic challenge. We provide evidence-based recommendations for core phenotyping domains and recommend measures of each domain.

Buprenorphine transdermal system and quality of life in opioid-experienced patients with chronic low back pain

Objectives: To evaluate the impact of 12 weeks of treatment with Butrans® (buprenorphine) transdermal system (BTDS) on the health-related quality of life (HRQoL) for patients with chronic low back pain (CLBP), and the maintenance of effects over 52 weeks. Research design and methods: A multicenter, enriched, double-blind (DB), randomized trial comparing BTDS 20 μg/h (BTDS 20) against 5 μg/h (BTDS 5) for treatment of opioid-experienced patients with moderate-to-severe CLBP, including a 52-week open-label (OL) extension phase. Main outcome measures: QoL was measured with the SF-36v2 survey before and after an OL run-in period with BTDS 20, three times during the DB phase, and seven times over the extension phase. This post hoc analysis tested for SF-36v2 score differences between treatment groups during the DB phase and maintenance of effects over the extension phase. Results: At 12 weeks, BTDS 20 produced larger improvements than BTDS 5 in role limitations due to physical health, bodily pain and overall physical QoL (p < 0.01). Treatment group differences in overall physical QoL were sustained throughout the DB phase. Quality-of-life improvements associated with BTDS 20 persisted through the extension phase. Conclusions: These data suggest that opioid-experienced moderate-to-severe CLBP patients receiving BTDS 20 exhibited better QoL than patients receiving BTDS 5.

12-Month safety and effectiveness of once-daily hydrocodone tablets formulated with abuse-deterrent properties in patients with moderate to severe chronic pain.

OBJECTIVE To characterize the long-term safety and effectiveness of Hysingla™ ER, single-entity, once-daily, extended-release hydrocodone bitartrate tablets formulated with abuse-deterrent properties (HYD), offering a new treatment option for appropriate patients with chronic pain. DESIGN An open-label study with a dose-titration period (up to 45 days) and a maintenance period (12 months). PATIENTS, PARTICIPANTS A total of 922 patients with chronic nonmalignant and non-neuropathic moderate to severe pain received open-label HYD tablets 20-120 mg; 728 of these achieved a stabilized dose of HYD at the end of dose-titration and entered the maintenance period. RESULTS The safety profile was similar to that of other oral opioid analgesics, without new or unexpected safety concerns. The most frequent treatment-emergent adverse events (AEs; ≥ 5 percent) were those commonly associated with the use of systemic µ-opioid analgesics, including nausea, constipation, vomiting, fatigue, dizziness, somnolence, and headache. There were 77 (8 percent) patients with a total of 109 nonfatal treatment-emergent serious AEs. Few patients discontinued due to lack of therapeutic effect overall (6 percent), especially during the 12-month maintenance period (4 percent). Pain relief, sleep, functional health, and activities of daily living all improved at the end of the dose-titration period with HYD. These improvements were maintained through the 12-month maintenance period with stable HYD doses and without increase in concomitant supplemental analgesic medications. CONCLUSIONS This long-term study demonstrated the safety and long-term maintenance of analgesic effect of HYD without continued need for dose increase.

A multicenter, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of single-entity, once-daily hydrocodone tablets in patients with uncontrolled moderate to severe chronic low back pain

Objectives: This multicenter, randomized, double-blind, placebo-controlled study with an enriched enrollment, randomized withdrawal design was conducted to evaluate the analgesic efficacy and safety of single-entity, once-daily hydrocodone 20 to 120 mg tablets (HYD) in opioid-naive and opioid-experienced patients with uncontrolled moderate to severe chronic low back pain (CLBP). Research design and methods: The primary endpoint was week 12 pain intensity scores (11-point scale, 0 = no pain) using a mixed effect model with repeated measures incorporating a pattern mixture model framework. Responder analysis was a secondary endpoint. Safety was assessed. Results: Out of 905 patients who were treated with HYD during the open-label titration period, 588 (65%) were randomized to continue to receive HYD (n = 296, 20 – 120 mg taken once daily, average daily dose 57 mg) or a matching placebo (n = 292). HYD demonstrated superior pain reduction (p = 0.0016); this result was supported by sensitivity analyses using different approaches to handling missing data. Proportions of patients achieving ≥ 30 and ≥ 50% improvement in pain from screening to week 12 also favored HYD (p = 0.0033 and 0.0225, respectively). HYD was generally well tolerated. Conclusions: HYD was shown to be an efficacious treatment for CLBP in this study. There were no new or unexpected safety concerns detected.

Pain intensity and interference with functioning and well-being in subgroups of patients with chronic pain treated with once-daily hydrocodone tablets

BACKGROUND A previous 52-week trial of patients with chronic noncancer, non-neuropathic pain (CNNP) showed clinically meaningful improvement in pain intensity, pain interference, and physical health-related quality of life (HRQL) following daily treatment with an extended-release, once-daily hydrocodone (Hysingla(®) ER; HYD) bitartrate tablet. OBJECTIVE To examine treatment response within patient subgroups and to assess between-subgroup differences in effectiveness and side effect profile. METHODS Data were from an open-label 52-week trial of treatment with HYD tablets (20-120 mg, once-daily) for patients with moderate-to-severe CNNP. Binary subgroups were defined for the following six factors: age, gender, opioid experience, baseline pain severity, history of depression, and stable HYD dose at completion of a 45-day dose-titration period. Univariable and multivariable models examined changes in average pain intensity (API; 11-point numeric rating scale), pain interference (Brief Pain Inventory-Interference subscale [BPI-I]), physical and mental HRQL (36-item Short Form health survey Physical and Mental Component Summaries [PCS and MCS]), and sleep quality (Medical Outcomes Study Sleep Scale Sleep Problems Index [SPI]) from baseline to maintenance, and subgroup differences in adverse events. RESULTS All subgroups showed clinically meaningful improvements in API, BPII, and PCS scores; no subgroups showed improvements in MCS or SPI. Between subgroup comparisons found greater improvements for opioid-naïve patients and for patients with severe baseline pain. Incidence of adverse events differed minimally between subgroups. CONCLUSION Regardless of subgroup, patients with CNNP treated with HYD showed clinically meaningful improvements in pain intensity, pain interference, and physical HRQL, although not in mental HRQL or sleep quality. Improvements were generally larger for opioid-naïve patients and patients with severe baseline pain.

Application site adverse events associated with the buprenorphine transdermal system: a pooled analysis.

Objective: To characterize the profile of application site reactions (ASRs) for patients treated with the buprenorphine transdermal system (BTDS) in chronic pain studies. Methods: The incidences of ASRs during treatment with BTDS were examined using (a) integrated data from 16 controlled and uncontrolled Phase III chronic pain studies (N = 6566), (b) a subset of integrated data that focused on the double-blind phases of five enriched, placebo-controlled studies (n = 1806) and (c) data from an international postmarketing drug safety database. These data were compared with the ASR data reported in the full prescribing information of other transdermal patches marketed in the US. Results: Among the 6566 patients, the overall incidence of ASRs was 23.4%, of which 98.3% were mild to moderate in intensity, none were serious and 4.4% led to treatment discontinuation. Rates of severe and inflammatory ASRs were low. Among the 1806 patients, ASR rates were higher with BTDS (16.6%) than placebo transdermal system (12.7%). Among the 6566 patients, the 1806 patients, and the postmarketing data, the most common ASRs seen were pruritus, erythema and rash. Incidences of most ASRs for other selected transdermal products were 17% or lower. Conclusion: Incidence rates of ASRs in patients treated with BTDS were low and infrequently led to discontinuation. Severe and inflammatory-type ASRs were not common. The ASR profile of BTDS was comparable with those of other transdermal patches.

Buprenorphine Transdermal System Improves Sleep Quality and Reduces Sleep Disturbance in Patients with Moderate-to-Severe Chronic Low Back Pain: Results from Two Randomized Controlled Trials

To evaluate the impact of buprenorphine (Butrans®) transdermal System (BTDS) treatment on sleep outcomes for patients with moderate‐to‐severe chronic low back pain (CLBP).

Efficacy and safety of once-daily, extended-release hydrocodone in individuals previously receiving hydrocodone/acetaminophen combination therapy for chronic pain

Abstract Background: Hydrocodone/acetaminophen combination analgesics are frequently prescribed for chronic pain management; however, acetaminophen presents potential hepatotoxicity to patients and thus dose limitations. These opioid medications are also widely abused. Once-daily, single-entity hydrocodone (Hysingla™ ER tablets [HYD]) is a novel formulation with abuse-deterrent properties for the management of chronic pain and represents a suitable option for those patients receiving analgesics containing the same opioid analgesic, hydrocodone. This post-hoc analysis evaluated the efficacy and safety of HYD in patients whose primary pre-study analgesic was hydrocodone/acetaminophen analgesics (23–31% of the study populations). Methods: Data were analyzed from two Phase III trials, a 12-week randomized, placebo-controlled trial (RCT) and an open-label, 52-week trial. In both trials, a dose-titration period with HYD was followed by respective periods of fixed-dose double-blind (randomized controlled trial [RCT]) or open-label, flexible-dose maintenance treatment. Pain intensity was assessed using a numerical rating scale (0–10, 0 = no pain). For the RCT, primary and sensitivity analyses of pain scores used different approaches to handle missing data. Safety data for both studies were summarized. Results: In the RCT, the mean baseline pain score was 7.3. Pain relief was greater with HYD than placebo during double-blind treatment. In the open-label, flexible-dose trial, the majority of patients were maintained on their titrated dose. Mean baseline pain score was 6.3, about 57% of patients completed the 1-year maintenance period, and mean pain scores were between 3.6 and 4.1 during the maintenance period. Use of supplemental pain medication decreased or was maintained during the maintenance treatment with HYD. Adverse events in both trials were typical of those associated with opioid analgesics. Conclusion: In patients whose primary pretrial analgesic was hydrocodone/acetaminophen combination tablets, single-entity HYD was effective in reducing pain intensity and in maintaining analgesia over time without need for continued dose increase. HYD’s safety and tolerability profiles were similar to other opioid analgesics.

A randomized, 14-day, double-blind study evaluating conversion from hydrocodone/acetaminophen (Vicodin) to buprenorphine transdermal system 10 μg/h or 20 μg/h in patients with osteoarthritis pain

Objective: The objective of this study was to evaluate continued pain control and tolerability of converting patients from Vicodin® (hydrocodone/acetaminophen; HCD/APAP) to the buprenorphine transdermal system (BTDS). Methods: Adult patients with pain from osteoarthritis receiving a stable dosage of HCD/APAP (i.e., 15 – 30 mg hydrocodone/day) were switched to an equivalent or near-equivalent dosage of open-label Vicodin for 7 days. Patients maintaining acceptable analgesia were stratified based on their Vicodin dosage and randomized to receive either titratable BTDS 10 μg/h or fixed-dose BTDS 20 μg/h. The primary efficacy variable was completion of the 14-day double-blind phase. Tolerability was assessed. Results: A total of 84.3% of patients met the primary end point, completion of the 14-day double-blind phase (167/198 patients, 95% CI 79.3 – 89.4). Adverse events were consistent with those associated with the use of opioid analgesics and transdermal patches. Conclusion: There was a similar analgesic and tolerability profile when patients treated with Vicodin for osteoarthritis pain were switched to 7-day BTDS treatment.

The impact of buprenorphine transdermal delivery system on activities of daily living among patients with chronic low back pain: An application of the international classification of functioning, disability and health

Objectives:The Buprenorphine Transdermal Delivery System (BTDS) is indicated for reduction of pain in moderate to severe chronic low back pain (CLBP), which can affect patients’ ability to perform routine activities of daily living (ADLs). This post hoc analysis of clinical trial data examines the impact of BTDS treatment on CLBP patients’ ability to perform ADLs that relate to functioning with low back pain. Methods:Data are drawn from a multicenter, enriched enrollment, randomized, placebo-controlled, double-blind 12-week trial of BTDS for pain control among opioid-naive patients with moderate to severe CLBP. The 23 selected ADLs are those that (1) appear in the Low Back Pain Core Set of the International Classification of Functioning, Disability and Health and (2) link to the content of 3 patient-reported outcome instruments administered during the trial. Logistic regression models estimated the odds ratios (ORs) of BTDS patients’ ability to perform each ADL at 12 weeks, controlling for baseline ability, relative to placebo. Results:The ORs for 10 ADLs related to sleeping, lifting, bending, and working reached multiplicity-adjusted statistical significance and indicated a greater ability to perform ADLs among BTDS users than among the placebo group. These 10 ORs ranged from 1.9 (no physical health-related restrictions on the kind of work performed) to 2.4 (being able to sleep undisturbed by pain). Discussion:These results suggest that for patients with moderate to severe CLBP, 12 weeks use of BTDS improves the ability to carry out certain ADLs related to sleeping, lifting, bending, and working.