A previous Cochrane review examined the efficacy and tolerability of nicotine receptor partial agonists including varenicline.16 Trials were excluded if participants used smokeless tobacco or if there was less than six months of follow-up. In addition to the efficacy outcomes, meta-analyses were performed for the most commonly reported adverse events: nausea, insomnia, abnormal dreams, and headache. Findings were consistent with our study for insomnia (relative risk 1.62, 95% confidence interval 1.40 to 1.88) and abnormal dreams (2.91, 2.34 to 3.62).16 The Cochrane review did not report any treatment emergent deaths. Although we used a broader definition of deaths in our analysis by including all deaths irrespective of whether or not we thought they were related to treatment, we did not find an increased risk of death in the varenicline group.
