Does preference for type of treatment matter? A study of exposure in vivo with or without hypnosis in the treatment of panic disorder with agoraphobia.

There is evidence that preference for a given therapy may influence results. Literature also suggests that hypnotizability may be elevated in agoraphobic patients, making hypnosis a potentially powerful method for treatment. Agoraphobic patients (N = 64) were treated with either exposure in vivo or exposure combined with hypnosis in a crossover design. Half of the patients started with the treatment they preferred and the other half received the other treatment first. Although patients' preference clearly shifted in favor of the combined therapy in the course of the study, no effect of preference on outcome was evident. Although hypnotizability clearly correlated to outcome in the combined therapy, no difference in effect between the two therapies was found on behavioral, self-report, and observer measures. No additional effect of hypnosis could be shown and preference was not found to be a powerful mediator of effect.