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.

Key words::

• Asia
• Clinical trial
• Smoking
• Smoking cessation
• Varenicline

Transparency

Declaration of funding

This study was sponsored by Pfizer Inc, who reviewed the content of this manuscript.

Declaration of financial/other relationships

K.F. has disclosed that he has consulted for most companies with an interest in tobacco dependence treatments, including Pfizer Inc; M.N. has disclosed that he has consulted for a number of companies with an interest in clinical trials of medication and medical professionals training for tobacco dependence treatments, including Pfizer Inc; and that he has received a research grant from Pfizer Foundation (New York, USA) through his institution. H.C. has disclosed that he has received research funds and consulting fees from Pfizer Inc; S.T. has disclosed attendance at Pfizer-sponsored advisory panels. C.W. has disclosed acting as a consultant for a number of companies with an interest in tobacco dependence treatments. K.F., M.N., H.C, S. T., and C.W. have disclosed that they have been investigators for Pfizer-sponsored clinical trials. S.D., W.M., T.L., and C.R. have disclosed that they are all employees of Pfizer Inc. Peer reviewers may receive honoraria from CMRO for their review work. The peer reviewers have disclosed no relevant financial interests.

Acknowledgements

Editorial support was provided by Alexandra Bruce, PhD, at UBC Scientific Solutions, and was funded by Pfizer Inc.

Some of the data contained in this manuscript were presented in poster format at the 2009 Joint Conference of SRNT and SRNT-Europe, 27–30 April 2009, Dublin, Ireland.

Notes

*Pfizer Inc, New York, NY, USA.