Smoking strongly predicts disability retirement due to COPD: the Finnish Twin Cohort Study.

No previous studies on the association of smoking behaviour with disability retirement due to register verified chronic obstructive pulmonary disease (COPD) exist. This 30-yr follow-up study examined how strongly aspects of cigarette smoking predict disability retirement due to COPD. The study population consisted of 24,043 adult Finnish twins (49.7% females) followed from 1975 to 2004. At baseline the participants had responded to a questionnaire. Information on retirement was obtained from the Finnish pension registers. Smoking strongly predicted disability retirement due to COPD. In comparison to never-smokers, age adjusted hazard ratio (HR) for current smokers was 22.0 (95% CI 10.0-48.5) and for smokers with ≥ 12 pack-yrs was 27.3 (95% CI 12.6-59.5). Similar estimates of risk were observed in within-pair analyses of twin pairs discordant for disability retirement due to COPD. Among discordant monozygotic pairs those with disability pension due to COPD were more often current smokers. The effect of early smoking onset (< 18 yrs) on the risk of disability retirement due to COPD remained after adjustment for the amount smoked (HR 1.70, 95% CI 1.08-2.68). Smoking strongly predicts disability retirement due to COPD. Preventive measures against disability retirement and other harmful consequences of tobacco smoking should receive greater emphasis.