Eight RCTs (n=7,477 patients) were included in the review. Three trials were considered to be good quality, two moderate quality and three low quality. Only three trials used appropriate randomisation, two reported allocation concealment, four reported blinding of outcome assessors, three reported blinding of treatment providers, three reported blinding of patients and five conducted an intention-to treat analysis.
Smoking cessation (eight RCTs): The most effective smoking cessation treatment was smoking cessation counselling combined with nicotine replacement therapy (OR 5.08, 95% CI 4.32 to 5.97), compared with usual care/no intervention. Smoking cessation counselling plus antidepressants were also significantly more effective than usual care/no intervention (OR 3.32, 95% CI 1.53 to 7.21); both these interventions were significantly more effective than smoking cessation counselling alone. There was no significant difference between smoking cessation counselling plus antidepressants and smoking cessation counselling plus nicotine replacement therapy, or between smoking cessation counselling alone and usual care/no intervention. The odds of prolonged abstinence tended to be increased by high-intensity smoking cessation counselling compared with low-intensity smoking cessation counselling, but these comparisons were only significant for low-intensity smoking cessation counselling plus nicotine replacement therapy versus high-intensity smoking cessation counselling plus nicotine replacement therapy (OR 1.81, 95% CI 1.04 to 3.15).
Mortality (two RCTs): One RCT reported that mortality was significantly reduced after 14.5 years (OR 0.74, 95% CI 0.63 to 0.87) among those who received smoking cessation counselling plus nicotine replacement therapy compared with those receiving usual care. A second RCT also reported lower mortality among those in the intervention group, but this association was not statistically significant and duration of follow-up was only one year.