Adverse short-term effects of attention-control treatment on hypnotizability: A challenge in designing controlled hypnosis trials

Characteristics of patients in test and attention-control groups should be comparable and be unaffected by the intervention to be tested in clinical trials. The authors assessed whether this is the case for measures of hypnotizability in the postoperative period. One hundred and forty-six patients undergoing percutaneous peripheral vascular or renal interventions were randomized into 2 groups. One group received structured empathic attention during their procedures; the other was guided to self-hypnotic relaxation. Hypnotizability was assessed postoperatively by the Hypnotic Induction Profile. The eye-roll scores, which measure the biological hypnotic potential, were not significantly different, but the average induction scores, which measure the expression of the hypnotic performance, were significantly lower in the attention group than the hypnosis group (4.9 vs. 5.9). The authors conclude that patients who were aided by an external focus intraoperatively are postoperatively less able or willing to follow suggestions measuring hypnotizability than patients who had guidance to self-hypnotic relaxation.