Effect of genetic polymorphisms and smoking histories of participants on nicotine dependence in current smokers: Regression analysis of the effect of smoking history on the association between genetic polymorphisms and nicotine dependence
Each analysis was performed for the whole cohort (the left side) and the male subgroup only (the right side). Forward-selection regression was conducted with the effect of the SLC6A3 and CYP2A6 genes. Variables were added one at a time to the model until no remaining variable produced a significant result. A: age at which participant began smoking, D; duration of smoking. R2, squared multiple correlation coefficient adjusted for degrees of freedom; AIC, Akaike’s information criterion. *The appropriate model was selected on the basis of minimising AIC.