Physical activity assessed in routine care predicts mortality after a COPD hospitalisation

Abstract

The independent relationship between physical inactivity and risk of death after an index chronic obstructive pulmonary disease (COPD) hospitalisation is unknown. We conducted a retrospective cohort study in a large integrated healthcare system. Patients were included if they were hospitalised for COPD between January 1, 2011 and December 31, 2011. All-cause mortality in the 12 months after discharge was the primary outcome. Physical activity, expressed as self-reported minutes of moderate to vigorous physical activity (MVPA), was routinely assessed at outpatient visits prior to hospitalisation. 1727 (73%) patients were inactive (0 min of MVPA per week), 412 (17%) were insufficiently active (1-149 min of MVPA per week) and 231 (10%) were active (≥150 min of MVPA per week). Adjusted Cox regression models assessed risk of death across the MVPA categories. Among 2370 patients (55% females and mean age 73±11 years), there were 464 (20%) deaths. Patients who were insufficiently active or active had a 28% (adjusted HR 0.72 (95% CI 0.54-0.97), p=0.03) and 47% (adjusted HR 0.53 (95% CI 0.34-0.84), p<0.01) lower risk of death, respectively, in the 12 months following an index COPD hospitalisation compared to inactive patients. Any level of MVPA is associated with lower risk of all-cause mortality after a COPD hospitalisation. Routine assessment of physical activity in clinical care would identify persons at high risk for dying after COPD hospitalisation.

FIGURE 1

Cohort selection. COPD: chronic obstructive pulmonary disease; ICD-9: International Classification of Diseases, Ninth Revision; CM: clinical modification.

FIGURE 2

Kaplan–Meier curves of 12-month survival after an index chronic obstructive pulmonary disease-related hospitalisation according to level of moderate and vigorous physical activity (Log rank test, p<0.0001).