Int. J. Environ. Res. Public Health 2012, 9 Cahill et al. 2007 [15] Stead et al. 2008 [22] Nicotine receptor partial agonists and placebo for smoking cessation Nicotine replacement therapy and placebo for smoking cessation Lancaster and Stead 2005 [17] Individual behavioural counseling RCTs in adult smokers Lost to follow up regarded as continuing smokers Control (placebo) usually involved some form of behavioural therapy. RCTs in adult smokers Lost to follow up regarded as continuing smokers Control (placebo) usually involved some form of behavioural therapy. Not all were properly randomised trials (but these were a minority of the trials included, most of which were properly randomised), and with versus no treatment, brief advice or self-help materials as the control Table 1. Cont. Minimum follow up of at least 6 months Minimum follow up of at least 6 months Minimum follow up of at least 6 months Abstinence from smoking, assessed at follow up by various means Abstinence from smoking, assessed at follow up by various means Abstinence from smoking, assessed at follow up by various means Reference Interventions Study characteristics Duration Outcome Abstinence with Intervention Placebo Varenecline 2 mg Placebo Smoking cessation at Smoking cessation 6 months or longer: at 6 months or 232/1,082 (21.4%) longer: 75/941 (8.0%) All NRT/doses Smoking cessation at 6 months or longer: 3,822/22,711 (16.8%) Behavioural therapy Smoking cessation at 6 months or longer: 291/2,513 (11.6%) All NRT/doses Smoking cessation at 6 months or longer: 2,115/20,307 (10.4%) Control Smoking cessation at 6 months or longer: 195/2,515 (7.8%) Comments RR 2.7 (2.1 to 3.5) RR 1.6 (1.5 to 1.7) Placebo results virtually identical for all modes of delivery of NRT RR 1.5 (1.3 to 1.8) 197