title: Physical activity as a predictor of thirty-day hospital readmission after a discharge for a clinical exacerbation of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Because physical inactivity in chronic obstructive pulmonary disease (COPD) predicts health care use and mortality, we prospectively evaluated the relationship of this variable to the frequency of 30-day readmissions after a hospitalization for an exacerbation.
  
  
  METHODS
  Consented patients discharged after an exacerbation of COPD were asked to wear a GT3X+ accelerometer (ActiGraph, Pensacola, FL) continuously on the wrist for 30 days after hospital discharge. Vector magnitude units (VMU), the sum of movements in three planes over each minute of use, were recorded. Higher physical activity for each minute was defined by a VMU threshold of at least 3,000 counts. Those patients with fewer than 60 minutes/day over the first week were considered inactive.
  
  
  RESULTS
  Fifty-four study patients were discharged from the hospital and 38 underwent 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). In addition, 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 1 after 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 two or more hospitalizations for exacerbations in the preceding year predicted 30-day readmission.
  
  
  CONCLUSIONS
  These findings underscore the importance of physical activity as a predictor of this type of health care use outcome.
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine.
authors.forename: Harsh
authors.initials: H
authors.lastname: Chawla
authors.forename: Chinthaka
authors.initials: C
authors.lastname: Bulathsinghala
authors.forename: John Patrick
authors.initials: JP
authors.lastname: Tejada
authors.forename: Dorothy
authors.initials: D
authors.lastname: Wakefield
authors.forename: Richard
authors.initials: R
authors.lastname: ZuWallack
mesh_terms: D061725:Accelerometry; D000368:Aged; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010351:Patient Discharge / Q000639:trends*; D010359:Patient Readmission / Q000639:trends*; D011379:Prognosis; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy
keywords: activity; chronic obstructive pulmonary disease; exacerbation