Physical Activity as a Predictor of Thirty-Day Hospital Re-Admission after a Discharge for a Clinical Exacerbation of COPD

Rationale: Physical inactivity in COPD predicts health care utilization and mortality.

Objectives: To prospectively evaluate the relationship of this variable to the frequency of 30-day readmissions.

Methods: Following a hospitalization for an exacerbation, consented patients discharged following an exacerbation of COPD were asked to wear an ActiGraph GT3X+ accelerometer continuously on the wrist for 30 days following hospital discharge. Vector magnitude units (VMU), the sum of movements in 3 planes over each minute of use, were recorded. Higher physical activity for each minute was defined by a threshold of VMU ≥ 3000 counts. Those patients with fewer than 60 minutes per day over the first week were considered inactive.

Measurements and Main Results: Fifty-four study patients were discharged from the hospital and 38 had activity testing. In the latter subgroup, all-cause hospital readmissions within 30 days occurred in 12 patients (32%). Minutes of higher physical activity per day over the first week after discharge were considerably lower in those eventually readmitted than in those who remained as outpatients: 42 ± 14 (SE) versus 114 ± 19 minutes, respectively, p = 0.02. Additionally, physical activity decreased over time in those who were eventually readmitted, but increased in those who were not readmitted. Those with lower physical activity over week one following discharge were more likely to have 30-day all-cause readmissions than those with higher activity: odds ratio 6.7, p = 0.02. In multivariate testing, both physical inactivity and a history of 2 or more hospitalizations for exacerbations in the preceding year both predicted 30-day readmission.

Conclusion: These findings underscore the importance of physical activity as a predictor of this type of health care utilization outcome.