title: Predicting daily physical activity in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Objectively measuring daily physical activity (PA) using an accelerometer is a relatively expensive and time-consuming undertaking. In routine clinical practice it would be useful to estimate PA in patients with chronic obstructive pulmonary disease (COPD) with more simple methods.
  
  
  OBJECTIVE
  To evaluate whether PA can be estimated by simple tests commonly used in clinical practice in patients with COPD.
  
  
  METHODS
  The average number of steps per day was measured for 7 days with a SenseWear Pro™ accelerometer and used as gold standard for PA. A physical activity level (PAL) of <1.4 was considered very inactive. Univariate and multivariate analyses were used to examine the relationship between the 6-minute walking distance (6MWD), the number of stands in the Sit-to-Stand Test (STST), hand-grip strength and the total energy expenditure as assessed by the Zutphen Physical Activity Questionnaire (TEE(ZPAQ)). ROC curve analysis was used to identify patients with an extremely inactive lifestyle (PAL<1.4).
  
  
  RESULTS
  In 70 patients with COPD (21 females) with a mean [SD] FEV(1) of 43.0 [22.0] %predicted, PA was found to be significantly and independently associated with the 6MWD (r = 0.69, 95% CI 0.54 to 0.80, p<0.001), STST (r = 0.51, 95% CI 0.31 to 0.66, p = 0.001) and TEEZPAQ (r = 0.50, 95% CI 0.30 to 0.66, p<0.001) but not with hand-grip strength. However, ROC curve analysis demonstrated that these tests cannot be used to reliably identify patients with an extremely inactive lifestyle.
  
  
  CONCLUSIONS
  In patients with COPD simple tests such as the 6-Minute Walk Test, the Sit-to-Stand Test and the Zutphen Physical Activity Questionnaire cannot be used to reliably predict physical inactivity.
authors.affiliation: Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland. vrns@zhaw.ch
authors.forename: Arnoldus J R
authors.initials: AJ
authors.lastname: van Gestel
authors.forename: Christian F
authors.initials: CF
authors.lastname: Clarenbach
authors.forename: Anne C
authors.initials: AC
authors.lastname: Stöwhas
authors.forename: Valentina A
authors.initials: VA
authors.lastname: Rossi
authors.forename: Noriane A
authors.initials: NA
authors.lastname: Sievi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Camen
authors.forename: Erich W
authors.initials: EW
authors.lastname: Russi
authors.forename: Malcolm
authors.initials: M
authors.lastname: Kohler
mesh_terms: D000054:Acceleration; D000203:Activities of Daily Living; D000368:Aged; D000886:Anthropometry / Q000379:methods; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D018737:Hand Strength; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000379:methods*; D009043:Motor Activity; D015999:Multivariate Analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D012372:ROC Curve; D012129:Respiratory Function Tests; D013147:Spirometry / Q000379:methods; D011795:Surveys and Questionnaires