Methods: The COMMIT cohort is a prospective cohort study designed to study community level interventions to encourage smoking cessation in a population-based sample of adult smokers in the U.S. and Canada. Participants were asked about smoking behaviors and cessation attempts. Of 13,415 participants surveyed in 1993, 3947 reported successful quit attempts (>6 months), and 1268 of these were resurveyed in 2001. Logistic Regression was used to model associations of potential covariates with risk of relapse.

Results: Of 1268 former smokers in 1993, 195 (15.4%) reported smoking in 2001. Age was associated with reduced risk of relapse (OR: 0.94, 95% CI 0.90, 0.99). Baseline measures of nicotine dependence and other demographic factors were not associated with risk of relapse. Those who cited concerns about their own health as motivation for quitting were less likely than others to relapse (OR: 0.62, 95% CI 0.40, 0.95), while those who cited concerns about secondhand smoke were more likely to relapse (OR: 1.44, 95% CI 1.04, 1.99).

Conclusions: Relapse occurs even after successful quit attempts. An improved understanding of relapse and its causes may provide additional strategies to improve population health.