Lung function decline over 25 years of follow-up among black and white adults in the ARIC study cohort

Background: Interpretation of longitudinal information about lung function decline from middle to older age has been limited by loss to follow-up that may be correlated with baseline lung function or the rate of decline. We conducted these analyses to estimate age-related decline in lung function across groups of race, sex, and smoking status while accounting for dropout from the Atherosclerosis Risk in Communities Study. Methods: We analyzed data from 13,896 black and white participants, aged 45–64 years at the 1987–1989 baseline clinical examination. Using spirometry data collected at baseline and two follow-up visits, we estimated annual population-averaged mean changes in forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) by race, sex, and smoking status using inverse-probability-weighted independence estimating equations conditioning-on-being-alive. Results: Estimated rates of FEV₁ decline estimated using inverse-probability-weighted independence estimating equations conditioning on being alive were higher among white than black participants at age 45 years (e.g., male never smokers: black: −29.5 ml/year; white: −51.9 ml/year), but higher among black than white participants by age 75 (black: −51.2 ml/year; white: −26). Observed differences by race were more pronounced among men than among women. By smoking status, FEV₁ declines were larger among current than former or never smokers at age 45 across all categories of race and sex. By age 60, FEV₁ decline was larger among former and never than current smokers. Estimated annual declines generated using unweighted generalized estimating equations were smaller for current smokers at younger ages in all four groups of race and sex compared with results from weighted analyses that accounted for attrition. Conclusions: Using methods accounting for dropout from an approximately 25-year health study, estimated rates of lung function decline varied by age, race, sex, and smoking status, with largest declines observed among current smokers at younger ages.