Individuals at higher genetic risk were more likely to progress to smoking ≥20 cigarettes/day and did so more rapidly (HR=1.35 [1.14-1.58]). Figure 3 Panel A shows the cumulative hazards for smoking ≥20 cigarettes/day for individuals at low, average, and high genetic risk. An unexpected finding was that individuals who initiated smoking but who did not progress to daily smoking or to heavy smoking, so-called “chippers”, were at the lowest genetic risk of any group in the cohort (Figure 3 Panel B).
