Body size and physical activity in relation to incidence of chronic obstructive pulmonary disease.

BACKGROUND Limited evidence suggests that adiposity and lack of physical activity may increase the risk of chronic obstructive pulmonary disease (COPD). We investigated the relation of body size and physical activity with incidence of COPD. METHODS We obtained data on anthropometric measurements and physical activity from 113,279 participants in the National Institutes of Health-AARP Diet and Health Study who reported no diagnosis of COPD at baseline (1995-1996). We estimated associations between these measurements and subsequent diagnosis of COPD between 1996 and 2006, with extensive adjustment for smoking and other potentially confounding variables. RESULTS Participants reported 3648 new COPD diagnoses during follow-up. The incidence of COPD was higher in both severely obese (body mass index [BMI] ≥ 35) and underweight (BMI < 18.5) participants, but after adjustment for waist circumference, only underweight remained positively associated with COPD (relative risk [RR] 1.56, 95% confidence interval [CI] 1.15-2.11). Larger waist circumference (highest v. normal categories, adjusted RR 1.72, 95% CI 1.37-2.16) and higher waist-hip ratio (highest v. normal categories, adjusted RR 1.46, 95% CI 1.23-1.73) were also positively associated with COPD. In contrast, hip circumference (highest v. normal categories, adjusted RR 0.78, 95% CI 0.62-0.98) and physical activity (≥ 5 v. 0 times/wk, adjusted RR 0.71, 95% CI 0.63-0.79) were inversely associated with COPD. INTERPRETATION Obesity, in particular abdominal adiposity, was associated with an increased risk of COPD, and increased hip circumference and physical activity were associated with a decreased risk of COPD. These findings suggest that following guidelines for a healthy body weight, body shape and physical activity decrease the risk of COPD.