Abstract
Background: Obesity is associated with poor function in general population studies, but there are few COPD-specific data on this question.
Methods: In a longitudinal cohort of 667 adults with COPD, we sequentially (baseline and 2 year follow-up) assessed the Short Physical Performance Battery (SPPB) and 6 minute walk distance (6MWD). We defined obesity by baseline body mass index (BMI>30 kg/m2) and fat mass index obtained from bioelectrical impedance analysis (FMI, fatkg/heightm2, obese defined as ≥75th %ile). Decline in SPPB and 6MWT was defined using published clinically important differences (1 point for SPPB and 30 for 6MWT). We tested differences in decline rates by each measure of obesity. Multivariate analyses controlled for age, sex, smoking, and baseline FEV1%predicted.
Results: Among those obese by BMI, 26.6% declined in SPPB and 24.3% in 6MWD vs. 18.6% and 16.4%, respectively, in the non-obese group (both p<0.05). Defined by FMI, incident SPPB decline was also more frequent in the obese compared to the non-obese (28.1% vs 20.5%; p=0.05), but the difference in 6MWD decline was less pronounced (24.6% vs. 18.4%; p=0.10). Multivariate results showed significantly increased odds of decline in SPPB (OR 1.7 [95% CI 1.1, 2.4]) and 6MWD (1.7 [1.2, 2.6]) for those obese by BMI. For those obese by FMI, odds of decline in SPPB (1.6 [1.1, 2.4]) and 6MWD (1.5 [1.0, 2.3]) were also elevated.
Discussion: Obesity is associated with longitudinal decline in physical function among adults with COPD, which is likely to be associated with worse disability and quality of life.
Clinical: Although low body mass has been recognized as a predictor of poor outcomes in COPD, obesity may also warrant clinical concern in this condition.
- © 2014 ERS
