The results of the five multi-predictor Cox proportional hazards models are shown in Table 3. Model 1 was the initial reference model and contained the five predictors from our previous study (Kuperman et al., 2013); the outcome of this model is based on the 674 subjects with available genotyping in the current study sample. Four of the five variables had adjusted hazard ratios (aHRs) that suggested an increase in the risk for drinking initiation: the number of CD symptoms, MBFD, YSR externalizing score, and being a member of a high-risk AD family; the YSR social problems score was no longer significant, and was dropped from Model 1. This resulted in a simplified reference model, Model 2. Model 3 contained the four predictors in Model 2 plus three covariates (sex, interview age, and ancestry, though only ancestry was significant). This model became the new reference model when evaluating the impact of the chosen candidate SNP. Model 4 contained all predictors from Model 3 plus the number of T alleles at rs279871 (additive genetic model). The likelihood of initiating drinking was 28%
