A Cochrane review included 25 studies involving a total over 22 000 subjects. 10 trials included two or more conditions allowing assessment of a dose-response to aversive stimulation.The odds ratio (OR) for abstinence following rapid smoking compared to control was 2.01 (95% CI 1.36 to 2.95, 10 trials). 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. 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 (OR 1.15, 95% CI 0.73 to 1.82). There was a borderline dose-response to the level of aversive stimulation (OR 1.67, 95% CI 0.99 to 2.81).
Comment: The quality of evidence is downgraded by several shortcomings in study quality, by potential reporting bias, and by imprecise results (limited study size for each comparison).