Hospital admissions and exercise capacity decline in patients with COPD

Abstract

Exercise capacity declines with time and is an important determinant of health status and prognosis in patients with chronic obstructive pulmonary disease (COPD). We hypothesised that hospital admissions are associated with exercise capacity decline in these patients. Clinical and functional variables were collected for 342 clinically stable COPD patients. The 6-min walk distance (6MWD) was determined at baseline and after a mean±sd of 1.7±0.3 years. Information on hospitalisations during follow-up was obtained from centralised administrative databases. Linear regression was used to model changes in exercise capacity. Patients were mostly male (92%), with mean±sd age 67.9±8.6 years, post-bronchodilator forced expiratory volume in 1 s 54±17% predicted and baseline 6MWD 433±93 m. During follow-up, 6MWD decreased by 21.9±51.0 m·year(-1) and 153 (45%) patients were hospitalised at least once. Among patients admitted only for COPD-related causes (50% of those ever admitted), the proportion presenting a clinically significant loss of 6MWD was higher than in patients admitted for only nonrespiratory conditions (53% versus 29%, p=0.040). After adjusting for confounders, annual 6MWD decline was greater (26 m·year(-1), 95% CI 13-38 m·year(-1); p<0.001) in patients with more than one all-cause hospitalisation per year, as compared with those with no hospitalisations. Hospitalisations are related to a greater decline in exercise capacity in COPD.