We used a standard series of Cox proportional hazard models to analyze age of smoking cessation in the ARIC study, and we used logistic regression to analyze biochemically confirmed end-of-treatment (EOT) point-prevalence abstinence in the UW-TTURC study. In the UW-TTURC study, days to relapse constituted a secondary outcome which was analyzed with Cox proportional hazard models. The primary predictor variables of interest were haplotypes and a haplotype-by-treatment interaction in the smoking cessation study. Covariates included gender, age (in quartiles), cigarettes per day (in 4 levels: <10, 11-20, 21-30, >31), and treatment (placebo versus active treatment in the UW-TTURC study).
