The journal of pain : official journal of the American Pain Society
-
The presence of bimodal outcome distributions has been used as a justification for conducting responder analyses, in addition to, or in place of analyses of the mean between-group difference, in clinical trials and systematic reviews of interventions for pain. The aim of this study was to investigate the distribution of participants' pain outcomes for evidence of bimodal distribution. We sourced data on participant outcomes from a convenience sample of 10 trials of nonsurgical interventions (exercise, manual therapy, medication) for spinal pain. ⋯ We found no compelling evidence suggesting that outcomes were bimodally distributed for any of the intervention groups. Responder analysis would not meaningfully alter our interpretation of these data compared with the mean between group difference. Our findings suggest that bimodal distribution of outcomes should not be assumed in interventions for spinal pain and do not support the automatic prioritization of responder analysis over the between group difference in the evaluation of treatment effectiveness for pain.
-
Randomized Controlled Trial
Endogenous Opioid Function and Responses to Morphine: The Moderating Effects of Anger Expressiveness.
Long-term use of opioid analgesics may be ineffective or associated with significant negative side effects for some people. At present, there is no sound method of identifying optimal opioid candidates. Individuals with chronic low back pain (n = 89) and healthy control individuals (n = 102) underwent ischemic pain induction with placebo, opioid blockade (naloxone), and morphine in counterbalanced order. ⋯ For individuals with chronic pain and healthy control participants, those with low endogenous opioid function and low anger-out scores exhibited the largest morphine analgesic responses, whereas those with high anger-out and low endogenous opioid function showed relatively weaker morphine analgesic responses. Further, individuals with chronic pain with low endogenous opioid function and low anger-out scores also reported the fewest negative effects to morphine, whereas those with low endogenous opioid function and high anger-out reported the most. Findings point toward individuals with chronic pain who may strike a favorable balance of good analgesia with few side effects, as well as those who have an unfavorable balance of poor analgesia and many side effects.
-
Randomized Controlled Trial
Migraine prevention using different frequencies of transcutaneous occipital nerve stimulation: A randomized controlled trial.
This study's objective was to evaluate the efficacy and tolerability of transcutaneous occipital nerve stimulation (tONS) in patients with migraine, and to explore whether different tONS frequencies influenced treatment effectiveness. This was a randomized, controlled trial of tONS for prevention of migraine. Patients were randomized to 1 of 5 therapeutic groups before treatment for 1 month. ⋯ From baseline to the 1-month treatment period, the tONS group with 100 Hz and topiramate group exhibited significant decreases in headache duration. We conclude that tONS therapy is a new promising approach for migraine prevention. It has infrequent and mild adverse events and may be effective among patients who prefer nonpharmacological treatment.
-
Prominent clinical models of chronic pain propose a fundamental role of classical conditioning in the development of pain-related disability. If classical conditioning is key to this process, then people with chronic pain may show a different response to pain-related conditioned stimuli than healthy control subjects. We set out to determine whether this is the case by undertaking a comprehensive and systematic review of the literature. ⋯ Because of variability in outcomes, meta-analyses included a maximum of 4 studies. People with chronic pain tended to show reduced differential learning and flatter generalization gradients with respect to US expectancy and fear-potentiated eyeblink startle responses. Some studies showed a propensity for greater muscular responses and perceptions of unpleasantness in response to pain-associated cues, relative to control cues.