A Cochrane review [Abstract] 1 included 81 studies involving a total of 69 094 participants. Trials were heterogeneous in terms of populations and interventions. 50 studies that randomized abstainers were considered separately from 29 studies that randomized participants prior to their quit date. Most studies were concerned with interventions focusing on identifying and resolving tempting situations.
No benefit was found of behavioural interventions like brief and 'skills-based' relapse prevention methods for women who had quit smoking due to pregnancy, or for smokers undergoing a period of enforced abstinence during hospitalisation or military training (RR 0.98, 95% CI 0.87 to 1.11; 11 trials, n=5523; follow-up 9-15 months).
For pharmacological interventions, extended varenicline in assisted abstainers (RR 1.23, 95% CI 1.08 to 1.4, 2 trials, n=1297; I² =82%; follow-up: 12 months), rimonabant in assisted abstainers (RR 1.29, 95% CI 1.08 to 1.55; 1 trial), and nicotine replacement therapy (NRT) in unaided abstainers (RR 1.24, 95% Cl 1.04 to 1.47; 2 trials, n=2261; I² =56%) significantly reduced relapse. Extended treatment with bupropion failed to detect a significant effect (RR 1.15, 95% CI 0.98 to 1.35; 6 studies, n=1697), as did NRT in assisted abstainers (RR 1.04, 95% CI 0.77 to 1.40; 2 trials, n=553, I²= 0%).
Comment: The quality of evidence is downgraded by inconsistency.
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