Aversive smoking for smoking cessation.

BACKGROUND Aversion therapy pairs the pleasurable stimulus of smoking a cigarette with some unpleasant stimulus. The objective is to extinguish the urge to smoke. OBJECTIVES This review has two aims. First, to determine the efficacy of rapid smoking and other aversive methods in helping smokers stop smoking. Second, to determine whether there is a dose-response effect on smoking cessation at different levels of aversive stimulation. SEARCH STRATEGY We searched the Cochrane Tobacco Addiction Group trials register for studies which evaluated any technique of aversive smoking. SELECTION CRITERIA Randomised trials which compared aversion treatments with 'inactive' procedures or which compared aversion treatments of different intensity for smoking cessation. Trials must have reported follow-up of least 6 months from beginning of treatment. DATA COLLECTION AND ANALYSIS We extracted data in duplicate on the study population, the type of aversion treatment, the outcome measure, method of randomisation and completeness of follow-up. The outcome measure was abstinence from smoking at maximum follow-up, using the strictest measure reported by the authors. Subjects lost to follow-up were regarded as smokers. Where appropriate, we performed meta-analysis using a fixed effects model. MAIN RESULTS Twenty four trials met the inclusion criteria. Ten included rapid smoking and ten used other aversion methods. Ten trials included two or more conditions allowing assessment of a dose-response to aversive stimulation. The odds ratio for abstinence following rapid smoking compared to control was 2.08 (95% confidence interval 1.39 to 3.12). Several factors suggest that this finding should be interpreted cautiously. A funnel plot of included studies was asymmetric, due to the relative absence of small studies with negative results. Most trials had a number of serious methodological problems likely to lead to spurious positive results. The only trial using biochemical validation of all self reported cessation gave a non significant result. Other aversion methods were not shown to be effective (odds ratio 1.19, 95% confidence interval 0.77 to 1.83). There was a borderline dose-response to the level of aversive stimulation (odds ratio 1.66, 95% confidence interval 1.00 to 2.78). REVIEWER'S CONCLUSIONS The existing studies provide insufficient evidence to determine the efficacy of rapid smoking, or whether there is a dose-response to aversive stimulation. Milder versions of aversive smoking seem to lack specific efficacy. Rapid smoking is an unproven method with sufficient indications of promise to warrant evaluation using modern rigorous methodology.