Varenicline treatment for smoking cessation in Asian populations: a pooled analysis of placebo-controlled trials conducted in six Asian countries

Abstract

Objective: A pooled analysis to evaluate the efficacy and safety of varenicline versus placebo for smoking cessation in Asian populations. A secondary objective was to compare the data to pooled trials among predominantly Western populations.

Research design and methods: Smokers (n = 893) in three randomized, double-blind, placebo-controlled, multicenter, phase IIb or III trials conducted in six Asian countries (Japan, Taiwan, Korea, China, Singapore, and Thailand), received varenicline (1 mg twice daily; n = 447) or placebo (n = 446) for 12 weeks. Non-treatment follow-up lasted 12 weeks (40 weeks in Japan). Primary endpoint was the carbon monoxide-confirmed continuous abstinence rate (CAR) for weeks 9-12 (last 4 weeks of treatment). Secondary endpoint was CAR for weeks 9-24.

Results: CAR was higher for varenicline than placebo during weeks 9-12 (58.6 vs. 34.3%; odds ratio [OR]: 2.74; 95% confidence interval [CI]: 2.08-3.60; p < 0.0001), and through 12 weeks of follow-up (CAR weeks 9-24; 41.4 vs. 25.3%; OR: 2.08; 95% CI: 1.56-2.77; p < 0.0001). The most frequent adverse events (AEs) in the varenicline group (greater incidence than the placebo group) were: nausea (31.5%), headache (8.5%), dizziness (7.8%), insomnia (7.4%), and upper abdominal pain (5.4%). Serious AEs occurred in four varenicline and five placebo participants. Discontinuations due to AEs occurred in 3.6% of varenicline and 1.6% of placebo participants. Compared with the Western studies, abstinence rates for both varenicline and placebo were numerically higher in the Asian studies, although treatment effects were similar between the two populations. AEs reported in the Asian trials were largely similar to those in the Western populations.

Conclusions: Varenicline significantly improved smoking abstinence in Asian populations from six countries. AEs were predominantly of mild or moderate intensity. These data were largely the same as those seen in Western populations, but the studies were not designed to explore racial or cultural differences.