Kaplan–Meier estimates of the time to relapse were computed. Next, the association between time to relapse and genetic and psychiatric predictors, as well as treatment condition, was then investigated using Cox regression models. Such models estimate a hazard ratio, which is the ratio of the estimated hazard (ie, probability of relapse) for those with the covariate (eg, genetic risk score, Fagerstrom nicotine dependence) to those without the covariate.
