The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial
Involvement of opioid receptors and α2-adrenoceptors in inhibitory pain modulation processes: a double-blind placebo-controlled crossover study.
In healthy humans, high-frequency electrical stimulation (HFS) of the forearm not only evokes local signs of central sensitization but also triggers broader ipsilateral inhibitory influences on pain akin to a lateralized form of conditioned pain modulation. Paradoxically, some of these inhibitory influences are augmented by α2-adrenoceptor blockade. To determine whether opioid peptides mediate inhibitory effects after HFS, the opioid receptor antagonist naltrexone was coadministered orally with the α2-adrenoceptor antagonist yohimbine in 16 healthy women in a double-blind placebo-controlled crossover study. ⋯ Unlike yohimbine alone, the naltrexone with yohimbine combination blocked analgesia evoked by HFS in the ipsilateral forehead to blunt pressure, and opposed the ipsilateral inhibitory effect of pain in the temple on electrically-evoked pain at the HFS-treated site in the forearm. These findings imply involvement of opioid peptides in an ipsilateral analgesic response that complements the more generalized form of conditioned pain modulation. Opioid mediation of this ipsilateral analgesic response appears to override opposing α2-adrenoceptor effects.
-
Thorough assessment and reporting of adverse events (AEs) facilitates a detailed understanding of a treatment's risk-benefit profile. Although the Consolidated Standards of Reporting Trials (CONSORT) 2004 statement provides recommendations regarding AE reporting, adherence to these standards is often inadequate. We investigated AE reporting in clinical trials of intravenous and invasive pain treatments published in 6 major anesthesiology and pain journals between 2000 to 2003 and 2006 to 2012. ⋯ Anesthesiology and pain journals were similar in AE reporting quality, although industry-sponsored trials reported more AE information than nonindustry sponsored trials. Improvement is needed in AE reporting in analgesic clinical trials. The CONSORT checklist and ACTTION AE recommendations can assist investigators and editors in improving clinical trial transparency and quality.
-
Opioid misuse, abuse, and overdose are a rapidly growing public health epidemic. Medicaid Lock-In Programs (MLIPs) are designed to prevent overutilization of controlled substances by Medicaid patients. However, despite widespread use, there is little information on their effect. ⋯ In our sample of 6,148 MLIP patients, the odds of having any opioid claim in a given month was 84% lower during MLIP enrollment relative to the period before enrollment (odds ratio = .16). MLIP enrollment also corresponded with a reduction in monthly number of opioid prescriptions by 1.13, monthly number of pharmacies by .61, and monthly Medicaid expenditures by $22.78. Although MLIPs may constitute a successful component of comprehensive efforts to reduce the potential overutilization of opioids, care should be taken to ensure that programs such as MLIPs do not constrain patients' legitimate needs for analgesic medications.
-
Randomized Controlled Trial
Exploring what factors mediate treatment effect: Example of the STarT Back study high-risk intervention.
Interventions developed to improve disability outcomes for low back pain (LBP) often show only small effects. Mediation analysis was used to investigate what led to the effectiveness of the STarT Back trial, a large primary care-based trial that treated patients consulting with LBP according to their risk of a poor outcome. The high-risk subgroup, randomized to receive either psychologically-informed physiotherapy (n = 93) or current best care (n = 45), was investigated to explore pain-related distress and pain intensity as potential mediators of the relationship between treatment allocation and change in disability. ⋯ Outcome was measured using the Roland-Morris Disability Questionnaire. Change in pain-related distress and pain intensity were found to have a significant mediating effect of .25 (standardized estimate, bootstrapped 95% confidence interval, .09-.39) on the relationship between treatment group allocation and change in disability outcome. This study adds to the evidence base of treatment mediation studies in pain research and the role of distress in influencing disability outcome in those with complex LBP.
-
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). ⋯ 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.