Predicting daily physical activity in patients with chronic obstructive pulmonary disease

PLoS One. 2012;7(11):e48081. doi: 10.1371/journal.pone.0048081. Epub 2012 Nov 2.

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.

Objectives: 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.

MeSH terms

  • Acceleration
  • Activities of Daily Living
  • Aged
  • Anthropometry / methods
  • Exercise Tolerance
  • Female
  • Forced Expiratory Volume
  • Hand Strength
  • Humans
  • Life Style
  • Male
  • Middle Aged
  • Monitoring, Ambulatory / methods*
  • Motor Activity*
  • Multivariate Analysis
  • Pulmonary Disease, Chronic Obstructive / complications
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • ROC Curve
  • Respiratory Function Tests
  • Spirometry / methods
  • Surveys and Questionnaires

Grant support

The authors have no support or funding to report.