Pain
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Randomized Controlled Trial Multicenter Study
Efficacy and Tolerability of Buccal Buprenorphine in Opioid-Experienced Patients With Moderate to Severe Chronic Low Back Pain: Results of a Phase 3, Enriched Enrollment, Randomized Withdrawal Study.
A buccal film of buprenorphine (BBUP) was evaluated for safety and efficacy in a multicenter, double-blind, placebo-controlled, enriched-enrollment, randomized-withdrawal study in opioid-experienced patients (30 to ≤160 mg/d morphine sulfate equivalent) with moderate to severe chronic low back pain taking around-the-clock opioid analgesics. Patients' opioid doses were tapered to ≤30 mg morphine sulfate equivalent before open-label titration with BBUP (range, 150-900 μg every 12 hours). Patients who responded (received adequate analgesia that was generally well tolerated for 14 days) were randomized to receive buprenorphine (n = 254) or placebo (n = 257) buccal film. ⋯ A significantly larger percentage of patients receiving BBUP than placebo had pain reductions ≥30% and ≥50% (P < 0.001 for both). In the double-blind portion of the study, the only adverse event reported more frequently with BBUP than placebo and in ≥5% of patients was vomiting (5.5% vs 2.3%). These findings demonstrate the efficacy and tolerability of BBUP in opioid-experienced patients taking around-the-clock opioid treatment for chronic low back pain.
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Cross-over trials are typically more efficient than parallel group trials in that the sample size required to yield a desired power is substantially smaller. It is important, however, to consider some issues specific to cross-over trials when designing and reporting them, and when evaluating the published results of such trials. This systematic review evaluated the quality of reporting and its evolution over time in articles of cross-over clinical trials of pharmacologic treatments for chronic pain published between 1993 and 2013. ⋯ These results and others presented in this article demonstrate deficiencies in reporting of cross-over trials for analgesic treatments. Clearer reporting in future trials could improve readers' ability to critically evaluate the results, use these data in meta-analyses, and plan future trials. Recommendations for proper reporting of cross-over trials that apply to any condition are provided.
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Adults with mood disorders frequently use prescription opioids. The factors associated with this increased use remain unclear. We used the Medical Expenditure Panel Surveys from 2005 to 2011 to measure the association of mood disorders with new opioid use and the transition to longer-term opioid use for a variety of pain conditions before and after controlling for patient characteristics and clinical disability. ⋯ After adjusting for sociodemographics and clinical disability, there was no association between mood disorders and new opioid use for likely acute (adjusted odds ratio [aOR] 1.05 [0.92-1.20]) or potentially chronic pain (aOR 0.91 [0.80-1.03]). However, there remained a strong association between mood disorders and the transition to longer-term opioid use for likely acute (aOR 1.77 [1.15-2.72]) and potentially chronic pain (aOR 1.95 [1.42-2.68]). Targeting the transition to longer-term opioid use may help clinicians reduce potentially inappropriate opioid prescriptions in this high-risk population.
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Variability in blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals reflects the moment-by-moment fluctuations in resting-state fMRI (rs-fMRI) activity within specific areas of the brain. Regional BOLD signal variability was recently proposed to serve an important functional role in the efficacy of neural systems because of its relationship to behavioural performance in aging and cognition studies. We previously showed that individuals who better cope with pain have greater fluctuations in interregional functional connectivity, but it is not known whether regional brain signal variability is a mechanism underlying pain coping. ⋯ We acquired resting-state fMRI and assessed pain threshold, suprathreshold temporal summation of pain, and the impact of pain on cognition in 80 healthy right-handed individuals. We found that regional BOLD signal variability: (1) inversely correlated with an individual's temporal summation of pain within the ascending nociceptive pathway (primary and secondary somatosensory cortex), default mode network, and salience network; (2) was correlated with an individual's ability to cope with pain during a cognitive interference task within the periaqueductal gray, a key opiate-rich brainstem structure for descending pain modulation; and (3) provided information not captured from interregional functional connectivity. Therefore, regional BOLD variability represents a pain metric with potential implications for prediction of chronic pain resilience vs vulnerability.