Table 2. Estimated age-adjusted incidence rate ratios (IRR) and 95% confidence intervals (CI) for developing CSCC by different types of tobacco.
| Tobacco variable | No. of casesa | Person-years accumulated | IRR (95% CI) |
|---|---|---|---|
| Reference (nontobacco users) | 209 | 1 920 810 | 1 (ref) |
| Cigarette smoker | 194 | 1 947 400 | 1.04 (0.85–1.26)b |
| Cigarettes smoked per day b , c | |||
| <10 | 105 | 836 590 | 1.12 (0.88–1.41) |
| 11–20 | 58 | 667 330 | 0.92 (0.69–1.24) |
| >20 | 26 | 405 710 | 0.90 (0.60–1.36) |
| Cigar smoker | 9 | 42 000 | 0.88 (0.45–1.71)b |
| Pipe smoker | 80 | 358 200 | 0.81 (0.62–1.05)b |
| Pipe tobacco (g) smoked per week | |||
| <80 | 75 | 338 180 | 0.77 (0.59–1.00) |
| ⩾80 | 5 | 19 790 | 1.12 (0.46–2.73) |
| Snuff dipper | 29 | 661 150 | 0.64 (0.44–0.95)b |
| Years of snuff dipping | |||
| <30 | 14 | 610 320 | 0.79 (0.46–1.38) |
| ⩾30 | 15 | 44 660 | 0.58 (0.34–0.99) |
| Mixed user | 235 | 1 607 340 | 1.08 (0.90–1.30)b |
| BMI | |||
| ⩽18.5 | 3 | 93 390 | 0.87 (0.28–2.71) |
| 18.6–25 | 372 | 4 153 490 | 1-ref |
| 26–29 | 326 | 1 986 410 | 0.95 (0.81–1.10) |
| >30 | 52 | 282 310 | 0.98 (0.73–1.32) |
a
The discrepancy in number of cases is due to missing information on dose.
b
Adjusted for all other tobacco categories
c
Stratified Cox proportional hazards model, on age.
BMI=body mass index; CSCC=cutaneous squamous cell carcinoma.