Small changes in six-minute walk distance are important in diffuse parenchymal lung disease

Respir Med. 2009 Oct;103(10):1430-5. doi: 10.1016/j.rmed.2009.04.024. Epub 2009 May 23.


The aim of this study was to determine the minimal important difference for the six-minute walk distance in people with diffuse parenchymal lung disease.

Methods: Forty-eight subjects (24 idiopathic pulmonary fibrosis) undertook the six-minute walk test before and after an 8-week exercise program. The minimal important difference was calculated using a distribution-based and an anchor-based method. A global rating of change scale was used as the external criterion to judge patients as clinically unchanged or changed.

Results: The mean change in six-minute walk distance in improved subjects was 50.0 m, compared to 4.0 m in unchanged subjects and a reduction of 64.3 m in those classified as worse (p<0.001). The receiver operating characteristic curve indicated a cut-off value for meaningful change of 30.5 m (area under the curve 0.89, 95% confidence interval 0.81-0.98) whilst the standard error of the mean method indicated a value of 33 m. Similar values were obtained when only subjects with idiopathic pulmonary fibrosis were included (29 and 34 m, respectively).

Conclusions: Small differences in six-minute walk distance, in the range 29-34 m, may be clinically significant for people with diffuse parenchymal lung disease.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Area Under Curve
  • Exercise Test / methods
  • Exercise Therapy
  • Female
  • Forced Expiratory Volume / physiology*
  • Humans
  • Idiopathic Pulmonary Fibrosis / physiopathology*
  • Male
  • Middle Aged
  • Practice Guidelines as Topic
  • Time Factors
  • Walking / physiology*