Low Lung Function Is Associated with High Population Attributable Fraction for Cardiovascular Mortality.

Abstract

Chronic lung diseases are associated with increased risk of mortality due to coronary heart disease (CHD). Nonetheless, the population attributable fraction (PAF) of lung function impairment relative to other established cardiovascular risk factors is unclear. To evaluate the PAF of low lung function for CHD mortality Methods: We harmonized and pooled lung function and clinical data across 8 US general population cohorts. Impaired lung function was defined as FEV1 and/or FVC ≤95% predicted on baseline spirometry. The association between CHD mortality and risk factors was assessed using cause-specific proportional hazards and Fine-Gray proportional subdistribution hazards models, treating non-CHD mortality as a competing risk. Models were adjusted for lung function as well as age, sex, race/ethnicity, educational attainment, body mass index, smoking status, pack-years of smoking, diabetes mellitus, HDL, and high LDL (≥130 mg/dl). PAF was calculated as the relative change in the average absolute risk of ten-year CHD mortality by elimination of lung function lower than 95% predicted. Among 35143 participants, 1844 of 13174 (14.0%) deaths were due to CHD. Compared to FEV1pp >95%, the sub-distribution adjusted hazards ratio (95%CI) for low FEV1pp was 1.30 (1.18-1.44). The PAF for FEV1pp≤95% was 12%, ranking low FEV1 third in the list of PAF for CHD mortality, after hypertension and diabetes. Low FEV1pp ranked second in the subgroup of active smokers (PAF 14%), after hypertension. Low lung function, even in the range considered clinically normal, ranks high in the list of attributable risk factors for CHD mortality and should be considered in cardiovascular risk stratification.