To illustrate the interaction between the combined genetic risk and pharmacotherapy (NRT vs. placebo), the absolute rates of continuous abstinence over 90 days are shown in Figure 4. In this study, the NNT for NRT varied with the four combined genetic risk levels: 2.6 for smokers with high-risk status based on CYP2A6 and CHRNA5 (44.5% of the sample), 3.7 for smokers with high-risk status based on CYP2A6 & low-risk status based on CHRNA5 (27.5% of the sample), 16.6 for smokers with low-risk status based on CYP2A6 and high-risk status on CHRNA5 (18.2% of the sample), and >1000 for smokers with low-risk status based on CYP2A6 and CHRNA5 (9.81% of the sample). The last very high value indicates the lack of any treatment effect in the lowest risk group. These NNT values may be contrasted with an overall NNT of 4.2 if NRT is given to everyone regardless of the genetic risk.
