Is the rationale more important than deception? A randomised controlled trial of open-label placebo analgesia

Locher C, Frey Nascimento A, Kirsch I, et al. Pain 2017;158:2320–8.

Healthy volunteers were recruited to an experimental heat pain analgesia randomised controlled trial. Forty healthy volunteers in each group were randomly assigned to deceptive placebos, no treatment, open-label placebo without rationale or open-label placebo with rationale (explaining that placebo is powerful and effective for pain). An inert white placebo cream was used once, and heat pain measurements (subjective intensity, unpleasantness and objective heat tolerance) were obtained before and after placebo cream treatment. There was no significant difference in any of the groups in objective heat pain tolerance after treatment (P=0.724). However, the two groups with a rationale (open-label placebo with rationale and deceptive placebos) reported significantly lower heat pain intensity (P=0.033) and unpleasantness (P=0.016) ratings compared with the open-label placebo without rationale group. There was no significant difference (P=0.272) …