Correspondence (reply): In Reply

We thank our colleagues Ploeger and Wolter for their supplementary comments on medical hypnosis.

Autogenic training by Schultz and the stepwise active hypnosis by Kretschmer stem from classical hypnosis, although in these techniques, autosuggestions of the patient are in the foreground. These methods are of great importance for the development of hypnotherapy in Germany (1). Unfortunately, to the best of our knowledge, no controlled studies have been carried out on either stepwise active hypnosis or “self-organized hypnotherapy.”

We agree that case reports are important for clinical practice. The textbook “Hypnose in Psychotherapie, Psychosomatik und Medizin. Ein Manual für die Praxis” (Hypnosis in Psychotherapy, Psychosomatics, and Medicine. A Manual for the Practice) combines case studies, basic research, and empirical findings by summarizing case series, controlled trials, and systematic reviews (1).

We appreciate the reference to other potential indications for medical hypnosis. We limited ourselves to systematic reviews with meta-analyses and at least 400 participants to describe those indications for which robust empirical evidence exists (2). We are aware of an additional meta-analysis that meets these criteria that has been recently published, which reveals the efficacy of hypnosis/guided imagery as compared to control groups, and in combination with cognitive behavioral therapy as compared to cognitive behavioral therapy alone, for fibromyalgia syndrome (3). The Milton H. Erickson Gesellschaft für Klinische Hypnose (Society for Clinical Hypnosis) also publishes an annual overview of new controlled trials and systematic reviews of clinical hypnosis and hypnotherapy, both for psychosocial medicine (psychiatry, psychosomatic, and psychotherapy) as well as for somatic medicine. Evidence of efficacy from controlled studies in somatic medicine comes from hypnosis as a supportive measure in breast cancer treatment (for instance, treating fatigue after radiotherapy) or hot flushes, among others (4).

We also support the call for increased N-of-1 trials in medicine to be performed. A protocol for a systematic review to N-of-1 trials for psychological interventions is available (5).

Within the framework of individualized medicine, analyzing responder rates (such as the number of patients with clinically relevant pain reduction or an improvement of health-related quality-of-life) in systematic reviews is more useful than presenting averages. Analysis of individual patient data from controlled trials on pain therapy have shown that the pain reduction rates often follow a bimodal distribution (5). However, while some patients experience a substantial (=50%) reduction in pain, the majority of patients have no or only a slight reduction in pain (<30%). Therefore, the primary outcome in our overview of meta-analyses on hypnosis treatment of irritable bowel syndrome was the number of patients with a clinically meaningful reduction of gastrointestinal symptoms (2).