The relationship between reduced lung function and cardiovascular mortality - A population-based study and a systematic review of the literature

Study objectives: Conditions that give rise to reduced lung function are frequently associated with low-grade systemic inflammation, which may lead to poor cardiovascular outcomes. We sought to determine the relationship between reduced FEV1 and cardiovascular mortality, independent of smoking. Design: Longitudinal population-based study and a metaanalysis of literature. Setting: Representative sample of the general population. Participants: Participants of the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study who were 40 to 60 years of age at baseline assessment (n = 1,861). Measurements and results: We compared the risk of cardiovascular mortality across quintiles of FEV1. Individuals in the lowest FEV1 quintile had the highest risk of cardiovascular mortality (relative risk [RR], 3.36; 95% confidence interval [CI], 1.54 to 7.34). Compared to FEV1 quintile 1, individuals in quintile 5 had a fivefold increase in the risk of death from ischemic heart disease (RR, 5.65; 95% CI, 2.26 to 14.13). We also performed a systematic review of large cohort studies (> 500 participants) that reported on the relationship between FEV1 and cardiovascular mortality (12 studies; n = 83,880 participants). Compared to participants in the highest FEV1 category, those with reduced FEV1 had a higher risk of cardiovascular mortality (pooled RR, 1.77; 95% CI, 1.56 to 1.97). Conclusions: There is strong epidemiologic evidence to indicate that reduced FEV1 is a marker for cardiovascular mortality independent of age, gender, and smoking history.