Perceived Treatment Assignment and Smoking Cessation in a Clinical Trial of Bupropion Versus Placebo

Introduction: Psychoactive effects of smoking cessation medications such as bupropion may allow participants in smoking cessation clinical trials to correctly guess their treatment assignment at rates greater than chance. Previous research has found an association between perceived treatment assignment and smoking cessation rates among moderate to heavy smokers (>= 10 cigarettes per day [cpd]) in two bupropion clinical trials. Methods: The aim of this study was to determine the impact of perceived treatment assignment on end-of-treatment cotinine-verified smoking abstinence at Week 7 and Week 26 among African American light smokers (<= 10 cpd) enrolled in a double-blind, placebo-controlled study of bupropion. Participants (n = 390) included in this study reported their perceived treatment assignment on the end-of-treatment (Week 7) survey. Results: Participants were predominantly female (63.1%), 48.1 years of age (SD = 11.2), and smoked an average of 8 cpd (SD = 2.5). Participants given bupropion were more likely to correctly guess their treatment assignment (69%; 140/203) than those assigned to placebo (51.3%; 96/187) (p < .0001). After adjusting for treatment condition, participants who perceived assignment to bupropion versus placebo were not more likely to be abstinent than those who perceived assignment to placebo at Week 7 or at Week 26. The interaction between treatment and perceived treatment assignment was also nonsignificant. Conclusions: Consistent with two previous studies testing bupropion, participants assigned to bupropion were more likely to correctly guess their treatment assignment than those assigned to placebo. However, in contrast to previous studies with heavier smokers, perceived treatment assignment did not significantly impact cotinine-verified abstinence in light smokers.