The journal of pain : official journal of the American Pain Society
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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.
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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.
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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.
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Facilitated pain mechanisms and impaired pain inhibition are often found in chronic pain patients. This study compared clinical pain profiles, pain sensitivity, as well as pronociceptive and antinociceptive mechanisms in patients with localized low back pain (n = 18), localized neck pain (n = 17), low back and radiating leg pain (n = 18), or neck and radiating arm pain (n = 17). It was hypothesized that patients with radiating pain had facilitated pain mechanisms and impaired pain inhibition compared with localized pain patients. ⋯ Temporal summation of pain was increased in patients with radiating back pain compared with localized back pain (P < .03). Patients with radiating arm pain or localized low back pain demonstrated hyperalgesia to heat and pressure in nonpainful body areas (P < .05), as well as well as a facilitated clinical pain profile compared with patients with localized neck pain (P = .03). Patients with radiating pain patterns demonstrated facilitated temporal summation suggesting differences in the underlying pain mechanisms between patients with localized back pain and radiating pain.
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Pain behavior plays a key role in many theoretical models of pain, with many of these models conceptualizing pain behaviors as potentially detrimental to patient functioning. We propose that a certain class of behaviors-talking to others about one's pain-related distress (ie, emotional disclosures of pain-related distress)-can be distinguished from other behaviors traditionally conceptualized as pain behaviors. ⋯ Emotion and relationships models are also applied to assert that disclosures of pain-related distress may have functions that are not shared with other pain behaviors. In addition to an expanded conceptualization of these verbal expressions of distress about pain, further directions are provided to spur new research as well as clinical recommendations concerning appropriate responses to these behaviors.