Rationale: Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality.

Objectives: To determine risk factors for and outcomes of rapid lung function decline in a cohort of adults in the United States.

Methods: We analyzed data from 15,536 adults aged 44–66 yr in the Atherosclerosis Risk in Communities study. We used Cox proportional hazard models to determine the risk of rapid lung function decline at 3 yr on mortality and COPD hospitalizations over the subsequent 8 yr.

Measurements and Main Results: Of those in the baseline cohort, 13,756 (88.5%) had spirometry at the Year 3 visit. The strongest risk factors for not having a follow-up spirometry were as follows: having Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 3 or 4 disease at baseline (adjusted odds ratio [OR] 2.8; 95% confidence interval [CI], 2.1–3.8), being black (adjusted OR, 2.4; 95% CI, 2.1–2.7), and being a current smoker (adjusted OR, 1.8; 95% CI, 1.5–2.0). Participants with GOLD stage 3 or 4 disease were also more likely to be in the most rapidly declining lung function quartile (adjusted OR, 3.7; 95% CI, 2.7–5.0). Overall, participants with the most rapidly declining lung function had a modestly increased risk of death (adjusted hazard ratio, 1.4; 95% CI, 1.2–1.7) and time to a COPD-related hospitalization (adjusted hazard ratio, 1.4; 95% CI, 1.2–1.8).

Conclusion: Rapid lung function decline was independently associated with a modest increased risk of COPD hospitalizations and deaths.