Adherence to treatment for tobacco dependence: Association with smoking abstinence and predictors of adherence

Introduction: Detailed analysis of adherence to tobacco cessation medications and predictors of adherence is sparse in published literature. In this analysis, we assessed adherence to tobacco dependence treatment, association of adherence with abstinence, and predictors of adherence. Methods: We analyzed pooled results from 2 randomized controlled trials. Adult smokers (N = 2,045) who were randomly assigned to 12 weeks of treatment and took at least 1 dose of the assigned medication (varenicline [692], bupropion sustained release [669], or placebo [684]) were included. Treatment adherence was defined as any subject who took ≥1 dose of study drug for ≥80% days during the 12-week treatment period ("completers" ). Smoking abstinence was assessed using carbon monoxide-confirmed 4-week continuous abstinence rate at end of treatment (Weeks 9-12). Results: Adherence rates for completers who received varenicline, bupropion, and placebo groups, respectively, were 99.3%, 98.8%, and 99.2%. There was a positive correlation between adherence to treatment and tobacco abstinence in all treatment groups. Treatment effect sizes (odds ratios) for active therapy compared with placebo were similar whether considering all subjects or only the completer subset. Age, cigarettes per day, and Week-2 abstinence were significant predictors of adherence for all treatment groups (all p <.05), with Week-2 abstinence the strongest predictor. Discussion: Adherence to pharmacotherapy for smoking cessation is highly correlated with improved tobacco abstinence. Early abstinence experience is a strong driver of adherence.