The continuous CYP2A6 metabolism metric was not associated with smoking initiation (p=0.63) nor with the development of daily smoking (p=0.42) in the COGA young adults (Table 2). Of the 270 young adults who initiated smoking but did not transition to daily smoking, essentially all of them (98%) failed to develop any of the more advanced smoking behaviors, including nicotine dependence and smoking within 5 minutes after waking. This supports the notion that daily smoking is a prerequisite for the development of advanced smoking behaviors. Therefore, subsequent analyses of advanced smoking milestones focused on the 506 daily smokers.
