Table 3

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 habitsNo of eventsCrude 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 smokers690111
    Never smokers710.13 (0.10 to 0.17)0.14 (0.08 to 0.25)0.10 (0.08 to 0.14)
    Sustained ex-smokers1060.25 (0.20 to 0.31)0.30 (0.18 to 0.50)0.20 (0.15 to 0.26)
    Quitters (<15 g/day)§420.36 (0.26 to 0.49)0.40 (29 to 0.55)0.28 (0.18 to 0.44)
    Quitters (≥15 g/day)§410.58 (0.43 to 0.80)0.66 (0.47 to 0.93)0.52 (0.33 to 0.80)
    Light smokers2280.58 (0.49 to 0.67)0.59 (0.51 to 0.70)0.55 (0.46 to 0.66)
    Reducers820.84 (0.66 to 1.05)0.93 (0.73 to 1.18)0.80 (0.60 to 1.06)
Inhalation habits
    Non-inhalers154111
    Inhalers8463.98 (3.55 to 4.47)3.23 (2.69 to 3.88)3.56 (2.88 to 4.40)
Tobacco type
    Cigarettes666111
    Cigars, cheroots or pipe1850.41 (0.35 to 0.48)0.65 (0.54 to 0.79)0.66 (0.53 to 0.81)
    Mixed tobacco types1430.54 (0.45 to 0.66)0.65 (0.52 to 0.80)0.71 (0.56 to 0.90)