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Systematic Review
To evaluate the effect and safety of hypnotherapy for smoking cessation.
The authors included three new trials in this update, which brings the total to 14 included studies that compared hypnotherapy with 22 different control interventions. The studies included a total of 1926 participants. Studies were diverse and a single meta-analysis was not possible.
The authors judged only one study to be at low risk of bias overall; they judged 10 studies to be at high risk of bias and three at unclear risk. Studies did not provide reliable evidence of a greater benefit from hypnotherapy compared with other interventions or no treatment for smoking cessation. Most individual studies did not find statistically significant differences in quit rates after six months or longer, and studies that did detect differences typically had methodological limitations.
Pooling small groups of relatively comparable studies did not provide reliable evidence for a specific effect of hypnotherapy relative to controls. There was low certainty evidence, limited by imprecision and risk of bias, that showed no statistically significant difference between hypnotherapy and attention-matched behavioural treatments (RR 1.21, 95% CI 0.91 to 1.61; I2 = 36%; 6 studies, 957 participants). Results were similarly imprecise, and also limited by risk of bias, when comparing hypnotherapy to intensive behavioural interventions (not matched for contact time) (RR 0.93, 95% CI 0.47 to 1.82; I2 = 0%; 2 studies, 211 participants; very low certainty evidence). Results from one small study (40 participants) detected a statistically significant benefit of hypnotherapy compared to no intervention (RR 19.00, 95% CI1.18 to 305.88), but this evidence was judged to be of very low certainty due to high risk of bias and imprecision. No significant differences were detected in comparisons of hypnotherapy with brief behavioural interventions (RR 0.98, 95% CI 0.57 to 1.69; IS = 0%; 2 studies, 269 participants), rapid/focused smoking (RR 1.00, 95% CI 0.43 to 2.33; I2 = 65%; 2 studies, 54 participants), and pharmacotherapies (RR 1.68,95% CI 0.88 to 3.20; I2 = 5%; 2 studies, 197 participants). When hypnotherapy was evaluated as an adjunct to other treatments, the pooled result from five studies showed a statistically significant benefit in favour of hypnotherapy (RR 2.10, 95% CI 1.31 to 3.35; IS = 62%; 224 participants); however, this result should be interpreted with caution due to the high risk of bias across studies and substantial statistical heterogeneity.
There is insufficient evidence to determine whether hypnotherapy is more effective for smoking cessation than other forms of behavioural support or unassisted quitting. If a benefit is present, current evidence suggests the benefit is small at most. There is very little evidence on whether hypnotherapy causes adverse effects, but the existing data show no evidence that it does. Further large, high-quality randomized controlled trials, and more comprehensive assessments of safety, are needed on this topic.