Haplotypes did not predict abstinence in the entire sample including both placebo and treatment groups. However, the association of haplotypes with abstinence depended upon treatment condition. In the placebo group, haplotype H3, which is associated with heavy smoking, predicts failed abstinence in comparison to haplotype H1 (OR=0.37, 95% CI=0.19-0.78, p=0.0081 for H3 compared to H1); overall haplotypes were associated with abstinence (X2=7.02, df=2, omnibus-p=0.030 for the overall haplotype effect in the placebo group). However, haplotype status was not associated with abstinence amongst individuals receiving active pharmacotherapy (X2=1.45, df=2, omnibus-p=0.48 for the overall haplotype effect). This is reflected by a significant interaction between treatment (placebo versus active treatment) and haplotypes (X2=8.97, df=2, omnibus-p=0.011 for the interaction) (Table 2; Figure 1).
