Table 3. Cox proportional hazards model for transition time from first cigarette to onset of regular smoking (n = 817).
Hazard Ratio (95% CI) | |
---|---|
Cannabis use* | 2.38 (1.83 - 3.11) |
Conduct disorder* | 1.64 (1.15 - 2.34) |
Alcohol use* | 1.56 (1.12 - 2.18) |
Age at first cigarettea | |
Early (<= 13 years)* | 0.43 (0.25 - 0.73) |
Late (>16 years) | 0.76 (0.54 - 1.05) |
Nicotine dependence risk group (based on paternal status)b | |
Group 1: high G, high E* | 1.66 (1.20 - 2.29) |
Group 2: high G, low E | 1.62 (1.00 - 2.61) |
Group 3: moderate G, low E | 1.36 (0.89 - 2.10) |
Maternal nicotine dependence (Fagerstrom proxy) | 1.05 (0.97 - 1.13) |
Alcohol dependence risk group (based on paternal status)b | |
Group 1: high G, high E | 0.81 (0.61 - 1.07) |
Group 2: high G, low E | 0.96 (0.66 - 1.41) |
Group 3: moderate G, low E | 0.91 (0.62 - 1.35) |
Early first cigarette X risk period up to 1 year after first cigarettec* | 2.68 (1.40 - 5.13) |
Early first cigarette X risk period 2-3 years after first cigarettec* | 6.51 (3.17 - 13.32) |
Hazard ratios relative to median age at first cigarette (14-15 years)
Hazard ratios relative to Group 4 (control)
Interaction terms included in the model to adjust for violation of proportional hazard assumption for alcohol use and for early age at first cigarette.
p <.05