Pain
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A critical component in development of opioid analgesics is assessment of their abuse liability (AL). Standardization of approaches and measures used in assessing AL have the potential to facilitate comparisons across studies, research laboratories, and drugs. The goal of this report is to provide consensus recommendations regarding core outcome measures for assessing the abuse potential of opioid medications in humans in a controlled laboratory setting. ⋯ A brief historical perspective on AL testing is provided, and those measures that can be considered primary and secondary outcomes and possible additional outcomes in AL assessment are then discussed. These outcome measures include the following: subjective effects (some of which comprise the primary outcome measures, including drug liking; physiological responses; drug self-administration behavior; and cognitive and psychomotor performance. Before presenting recommendations for standardized approaches and measures to be used in AL assessments, the appropriateness of using these measures in clinical trials with patients in pain is discussed.
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Distraction is a strategy that is commonly used to cope with pain. Results concerning the efficacy of distraction from both experimental and clinical studies are variable, however, and indicate that its efficacy may depend on particular circumstances. Several models propose that distraction may be less effective for people who display a large attentional bias towards pain-related information. ⋯ Results indicated that people who display a large attentional bias towards predictive cues of pain or who initially experience the pain as more painful benefit less from distraction on a subsequent test. No effects were found between attentional bias towards pain words, state-trait anxiety, catastrophic thinking, and the efficacy of distraction. Current findings suggest that distraction should not be used as a 'one size fits all' method to control pain, but only under more specific conditions.
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Randomized Controlled Trial
The hidden effects of blinded, placebo-controlled randomized trials: an experimental investigation.
The knowledge of having only a 50% chance of receiving an active drug can result in reduced efficacy in blinded randomized clinical trials (RCTs) compared to clinical practice (reduced external validity). Moreover, minor onset sensations associated with the drug (but not with an inert placebo) can further challenge the attribution of group differences to drug-specific efficacy (internal validity). We used a randomized experimental study with inert placebos (inert substance) vs active placebos (inducing minor sensations), and different instructions about group allocation (probability of receiving drug: 0%, 50%, 100%). ⋯ Moreover, minor drug onset sensations can challenge internal validity. Effect sizes for these mechanisms are medium, and can substantially compete with specific drug effects. For clinical trials, new study designs are needed that better control for these effects.