Risk of admission to hospital for COPD by changes in smoking habits, pattern of inhalation, and type of tobacco smoked
| Total study population (n=19709) | Omitting first 5 years | |||
|---|---|---|---|---|
| Smoking habits | No of events | Crude hazard ratio (95% CI)* | Adjusted hazard ratio (95% CI)† | Adjusted hazard ratios (95% CI)‡ |
| Results from Cox’s proportional hazards regression analysis. | ||||
| *Crude model adjusted for age, sex, and cohort of origin. | ||||
| †Multivariate hazard ratios adjusted for age, sex, cohort of origin, inhalation habits, type of tobacco smoked, and years of smoking (continuous covariate). | ||||
| ‡Multivariate model and with exclusion of hospital admissions until 5 years after second examination (number of events=947). | ||||
| §Stratified according to light or heavy smoking at the first examination. | ||||
| Smoking category | ||||
| Heavy smokers | 690 | 1 | 1 | 1 |
| Never smokers | 71 | 0.13 (0.10 to 0.17) | 0.14 (0.08 to 0.25) | 0.10 (0.08 to 0.14) |
| Sustained ex-smokers | 106 | 0.25 (0.20 to 0.31) | 0.30 (0.18 to 0.50) | 0.20 (0.15 to 0.26) |
| Quitters (<15 g/day)§ | 42 | 0.36 (0.26 to 0.49) | 0.40 (29 to 0.55) | 0.28 (0.18 to 0.44) |
| Quitters (≥15 g/day)§ | 41 | 0.58 (0.43 to 0.80) | 0.66 (0.47 to 0.93) | 0.52 (0.33 to 0.80) |
| Light smokers | 228 | 0.58 (0.49 to 0.67) | 0.59 (0.51 to 0.70) | 0.55 (0.46 to 0.66) |
| Reducers | 82 | 0.84 (0.66 to 1.05) | 0.93 (0.73 to 1.18) | 0.80 (0.60 to 1.06) |
| Inhalation habits | ||||
| Non-inhalers | 154 | 1 | 1 | 1 |
| Inhalers | 846 | 3.98 (3.55 to 4.47) | 3.23 (2.69 to 3.88) | 3.56 (2.88 to 4.40) |
| Tobacco type | ||||
| Cigarettes | 666 | 1 | 1 | 1 |
| Cigars, cheroots or pipe | 185 | 0.41 (0.35 to 0.48) | 0.65 (0.54 to 0.79) | 0.66 (0.53 to 0.81) |
| Mixed tobacco types | 143 | 0.54 (0.45 to 0.66) | 0.65 (0.52 to 0.80) | 0.71 (0.56 to 0.90) |