Because CHRNA5 was previously shown to predict smoking cessation and to interact with pharmacotherapy condition, we studied the joint effects of CYP2A6 and CHRNA5 on smoking relapse and the interactions between each gene and pharmacotherapy. The interaction of CYP2A6 and NRT remained significant, even after adjusting for the effect of CHRNA5 (interaction effect size=1.89, 95CI=1.09-3.29, p=0.025; Table S4). Similarly, the interaction effect of CHRNA5 and pharmacotherapy remained consistent with our previous findings (interaction effect size is 0.49, Wald=4.59, df=1, p=0.032, unadjusted for CYP2A6 and 0.48, Wald=3.57, df=1, p=0.059, adjusted for CYP2A6). There was no significant interaction between CHRNA5 and CYP2A6 on relapse (interaction effect size=1.15, 95%CI=0.62-2.17, p=0.66).
