No clear evidence that hypnotherapy for smoking cessation is more effective in the long term than no treatment or other interventions
- Correspondence to Timothy P Carmody
University of California, San Francisco, 4150 Clement Street, San Francisco, CA 94121, USA;
Hypnosis is a popular method used by many smokers to quit smoking. The results of a recent survey study1 indicated that hypnosis was among the most commonly used complimentary and alternative medicine treatments for tobacco cessation. Survey respondents generally considered hypnosis to be effective and expressed strong interest in its future use for smoking cessation. Although hypnosis has been claimed to be effective in clinical reports and uncontrolled studies, the evidence for its efficacy derived from controlled studies remains inconclusive. The efficacy of hypnosis for smoking cessation has been difficult to determine because of the variability in the types and content of hypnotic suggestions; number and frequency of treatment sessions; presence of other forms of treatment such as nicotine patches; assessment methods and outcomes achieved. Although randomised controlled studies of hypnosis have begun to emerge in the smoking cessation literature, the most recent clinical practice guidelines2 concluded that hypnosis for smoking cessation lacks adequate empirical support from randomised controlled studies.
For the present empirical review, the authors searched the Cochrane Tobacco Addiction Group Specialized Register, MEDLINE, EMBASE, AMED, SCI and SSCI databases, and identified 11 studies that met the inclusion criteria. In these studies, hypnosis was compared with 18 different control interventions. Each study was summarised in terms of participant characteristics, type and duration of hypnosis, nature of the control group, method of assessing smoking status, method of randomisation, completeness of follow-up and rating of overall methodological quality. The main outcome measure was abstinence from smoking after at least 6 months, and the most rigorous definition of abstinence in each trial was used, including biochemical validation where available. Effects were summarised as RR, and fixed-effect models were used, where possible.
Consistent with a previous Cochrane review,3 the present review showed significant heterogeneity across studies regarding comparisons between hypnosis, no treatment, advice or psychological treatment. The confidence intervals for direct comparisons of hypnosis with effective cessation treatments were too wide to infer equivalence. Sensitivity analyses based on hypnosis type or intensity were not conducted because of the limited number of studies that were directly comparable and diversity of interventions and control conditions. The authors concluded that hypnosis was not more effective than other interventions or no treatment and that there was not enough evidence to indicate that hypnosis was as effective as counselling for smoking cessation.
The methods used in this review were clearly described and well designed, and the data extraction methods and appraisal criteria were sufficiently rigorous. The conclusions reached by the authors appeared to accurately reflect the results of the empirical studies reviewed. The findings did not change the conclusions from previous work in this area, and the efficacy of hypnosis still needs to be confirmed in further randomised controlled trials. While theories underlying hypnosis as a psychological intervention are abundant, they lack empirical validation, as are the mechanisms by which hypnosis is thought to achieve its effect (ie, positive response expectancies, treatment credibility, suggestibility and enhanced self-efficacy). Some of these factors mediate the impact of non-hypnotic treatments such as cognitive–behavioural therapy. In addition, the importance of the distinction between hypnosis and self-hypnosis has yet to be determined. The benefit of continued practice and application of hypnotic suggestions in the self-hypnosis paradigm needs to be further evaluated.
Nursing professionals play a key role in providing evidence-based smoking cessation treatments. Nurses providing care in inpatient and outpatient medical settings may not be certified in hypnotherapy nor interested in obtaining such certification. Even if found to be effective, the public health reach of hypnosis as a smoking cessation treatment may not be extensive because of the limited number of health professionals who are certified in hypnotherapy. At the same time, there continues to be a high demand for hypnosis for smoking cessation. Therefore, nursing professionals providing smoking cessation treatments should be prepared to address this interest, understand the limitations in empirical support and be familiar with local practitioners who are certified in both hypnosis and smoking cessation so that such smokers can be provided with this referral information.