Journal of pain and symptom management
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J Pain Symptom Manage · Mar 2001
Randomized Controlled Trial Clinical TrialImpact of experimentally-induced expectancy on the analgesic efficacy of tramadol in chronic pain patients: a 2 x 2 factorial, randomized, placebo-controlled, double-blind trial.
Variations in treatment effects between drug trials are usually attributed to different patient characteristics, variations in outcome assessment, and random error. We have previously hypothesized that part of the variation in treatment effects between drug trials might be caused by differences in nonspecific factors. In a randomized clinical trial, we aimed to investigate whether experimentally induced expectancy can modify the analgesic effect of tramadol relative to placebo in chronic pain patients. ⋯ This trial did not discern a significant difference in the analgesic effect of tramadol between a positive and neutral expectancy group. This means that the phenomenon either does not exist, or we had an inappropriate model to demonstrate it. Regardless, this study demonstrates the type of quality trial that should be done to find out which non-specific factors, such as information regarding the expected effect, can modify treatment effects.