Table 6 Incidence rates per 1,000 person-years and risk of chronic bronchitis, during and after employment time 1970–2000, in different strata of smoking and gassings among pulp mill workers
Smoking | Gassings | Cases | Incidence | Crude risk | Cox models* |
|---|---|---|---|---|---|
HR (95% CI) | |||||
No | No | 12 | 0.9/1,000 | 1 | 1 |
No | Yes | 39 | 3.5/1,000 | 3.9 | 3.7 (1.8-7.7) |
Ever | No | 30 | 2.1/1,000 | 2.3 | 2.5 (1.2-5.0) |
Ever | Yes | 50 | 3.6/1,000 | 4.0 | 3.9 (1.9-7.8) |
Current smoking | Frequent gassings | Cases | Incidence | Crude risk | Cox models* |
HR (95% CI) | |||||
No | No | 12 | 0.9/1,000 | 1 | 1 |
No | Yes | 24 | 7.5/1,000 | 8.3 | 8.7 (3.5-22) |
Yes | No | 15 | 3.7/1,000 | 4.1 | 3.7 (1.6-8.1) |
Yes | Yes | 7 | 7.4/1,000 | 8.2 | 10.6 (3.1-36) |