Varenicline for smoking cessation in people with schizophrenia: systematic review and meta-analysis

We performed an updated meta-analysis of randomized double-blind placebo-controlled trials (RCTs) on the effects of varenicline adjuvant therapy for smoking cessation in people with schizophrenia, on the basis of a previous meta-analysis (Tsoi in Cochrane Database Syst Rev 2:CD007253, 2013). We searched PubMed, the Cochrane Library databases, and PsycINFO up to August 1, 2014. RCTs comparing varenicline adjuvant therapy with placebo in schizophrenia were included. The risk ratio (RR), number needed to harm (NNH), and standardized mean differences with its 95% confidence interval (CI) were used. Seven studies (total n = 439), including 6 with only schizophrenia (total n = 352), 1 with both schizophrenia (n = 77) and bipolar disorder (n = 10), were included. Varenicline was not superior to placebo in smoking cessation (RR = 0.79, 95% CI 0.58-1.08, p = 0.14, 5 RCTs, n = 322). Varenicline failed to show its superiority to placebo for overall, positive, negative, and depressive symptoms. Moreover, there was no significant difference in the discontinuation rate due to all causes, clinical deterioration, or side effects between varenicline and placebo. Although varenicline caused less abnormal dreams/nightmares than placebo (RR = 0.47, 95% CI 0.22-0.99, p = 0.05, NNH = not significant, 4 RCTs, n = 288), it caused more nausea (RR = 1.79, 95% CI 1.20-2.67, p = 0.004, NNH = 6, p = 0.004, 6 RCTs, n = 417). We detected no significant difference in suicidal ideation and depression between varenicline and placebo. Our results suggest that although varenicline adjuvant therapy is well tolerated, varenicline is not superior to placebo for smoking cessation in people with schizophrenia. Because of the limited sample sizes of the available studies, future studies will require larger samples to ensure that these findings are generalizable.