Background: Previous studies, all of <20 years of follow-up, have suggested an association between lung function and the risk of fatal stroke. This study investigates the stability of this association in a cohort followed for 4 decades.
Methods: The Bergen Clinical Blood Pressure Survey was conducted in Norway in 1964-1971. The risk of fatal stroke associated with forced expiratory volume after one second (FEV(1)) was estimated with Cox proportional hazards regression, making progressive adjustment for potential confounders.
Results: Of 5617 (84%) participants with recorded baseline FEV(1), 462 died from stroke over 152 786 subsequent person-years of follow-up according to mortality statistics of 2005; mean (SD) follow-up was 27 (12) years. An association between baseline FEV(1) (L) and fatal stroke was observed; HR=1.38 (95% CI 1.11 to 1.71) and HR=1.62 (95% CI 1.22 to 2.15) for men and women, respectively (adjusted for age and height). The findings were not explained by smoking, hypertension, diabetes, atherosclerosis, socioeconomic status, obstructive lung disease, physical inactivity, cholesterol or body mass index and persisted in subgroups of never-smokers, subgroups without respiratory symptoms and survivors of the first 20 years of follow-up. For male survivors with a valid FEV(1) at follow-up (1988-1990) (n=953), baseline FEV(1) (L) indicated a possible strong and independent association to the risk of fatal stroke after adjustments for individual changes in FEV(1) (ml/year) (HR 1.95 (95% CI 0.98 to 3.86)).
Conclusion: There is a consistent, independent and long-lasting association between lung function and fatal stroke, probably irrespective of changes during adult life.