title: Physical activity and the frequency of acute exacerbations in patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  Acute exacerbations (AE) in patients with COPD are associated with a decline in lung function, increased risk of hospitalization, and mortality. In this cross-sectional study we tested whether the level of objectively measured daily physical activity and exercise capacity are associated with the number of COPD exacerbations.
  
  
  METHODS
  In 210 patients with COPD (67 % men; mean (SD) age: 63 (8) years) enrolled in The Obstructive Pulmonary Disease Outcomes Cohort of Switzerland (TOPDOCS) physical activity (PA) (steps per day, physical activity level, (PAL)), exercise capacity (6-min walking distance, (6MWD)), comorbidities, lung function, and medication were assessed. Differences between COPD patients with frequent (≥2 year) and infrequent (0-1 year) exacerbations were assessed. Univariate and multivariate analyses were performed to investigate whether the level of objectively measured daily physical activity and exercise capacity are associated with the number of COPD exacerbations.
  
  
  RESULTS
  Patients with frequent AE had a significantly lower FEV1 and 6MWD compared to patients with infrequent AE. In univariate analysis, the number of exacerbations was inversely associated with FEV1, 6MWD, BMI, and smoking status while there was a positive association with RV/TLC and combined inhaled medication. However, there was no significant association with PAL and steps per day. In multivariate analysis, FEV1 and the use of combined inhaled medication were independently associated with the number of AE, after correction for covariates.
  
  
  CONCLUSIONS
  The findings of this study imply that FEV1, independent of inhaled medication, is significantly associated with COPD exacerbations. Neither physical activity nor exercise capacity was independently associated with COPD exacerbations.
authors.affiliation: Clinical Director Division of Pulmonology, University Hospital of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Schönmann
authors.forename: N A
authors.initials: NA
authors.lastname: Sievi
authors.forename: C F
authors.initials: CF
authors.lastname: Clarenbach
authors.forename: T
authors.initials: T
authors.lastname: Brack
authors.forename: M
authors.initials: M
authors.lastname: Brutsche
authors.forename: M
authors.initials: M
authors.lastname: Frey
authors.forename: S
authors.initials: S
authors.lastname: Irani
authors.forename: J D
authors.initials: JD
authors.lastname: Leuppi
authors.forename: J
authors.initials: J
authors.lastname: Ruediger
authors.forename: O
authors.initials: O
authors.lastname: Senn
authors.forename: R
authors.initials: R
authors.lastname: Thurnheer
authors.forename: M
authors.initials: M
authors.lastname: Kohler
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors; D012720:Severity of Illness Index; D013557:Switzerland / Q000453:epidemiology; D013997:Time Factors; D014109:Total Lung Capacity