Effect of Maintenance Therapy With Varenicline on Smoking Cessation<SUBTITLE>A Randomized Controlled Trial</SUBTITLE>

To determine whether smokers who quit after 12 weeks of treatment with varenicline, a selective alpha4beta2 nicotinic acetylcholine receptor partial agonist, maintain greater continuous abstinence rates (defined as not a single "puff" of a cigarette) than placebo controls during an additional 12 weeks of treatment and until 52 weeks after treatment initiation. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial conducted at multiple medical clinics in 7 countries with follow-up to 52 weeks after study baseline. Of 1927 cigarette smokers recruited between April 2003 and February 2004 and treated for 12 weeks with open-label varenicline titrated to 1 mg twice per day, 1236 (64.1%) did not smoke, use tobacco, or use nicotine replacement therapy during the last week of treatment and 62.8% (n = 1210) were randomized to additional treatment or placebo. INTERVENTION: Participants were randomly assigned to receive either double-blind varenicline, 1 mg twice per day (n = 603), or placebo (n = 607) for an additional 12 weeks. MAIN OUTCOME MEASURES: Carbon monoxide-confirmed continued abstinence during weeks 13 to 24 and weeks 13 to 52 of the study.

The carbon monoxide-confirmed continuous abstinence rate was significantly higher for the varenicline group than for the placebo group for weeks 13 to 24 (70.5% vs 49.6%; odds ratio [OR], 2.48; 95% confidence interval [CI], 1.95-3.16; P