Optimizing the 6-min walk test as a measure of exercise capacity in COPD

Divay Chandra, Robert A. Wise, Hrishikesh S. Kulkarni, Roberto P. Benzo, Gerard Criner, Barry Make, William A. Slivka, Andrew L. Ries, John J. Reilly, Fernando J. Martinez, Frank C. Sciurba

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22 Scopus citations

Abstract

Background: It is uncertain whether the effort and expense of performing a second walk for the 6-min walk test improves test performance. Hence, we attempted to quantify the improvement in 6-min walk distance if an additional walk were to be performed. Methods: We studied patients consecutively enrolled into the National Emphysema Treatment Trial who prior to randomization and after 6 to 10 weeks of pulmonary rehabilitation performed two 6-min walks on consecutive days (N = 396). Patients also performed two 6-min walks at 6-month follow-up after randomization to lung volume reduction surgery (n = 74) or optimal medical therapy (n = 64). We compared change in the first walk distance to change in the second, average-of-two, and best-of-two walk distances. Results: Compared with the change in the first walk distance, change in the average-of-two and best-of-two walk distances had better validity and precision. Specifically, 6 months after randomization to lung volume reduction surgery, changes in the average-of-two(r = 0.66 vs r = 0.58, P = .01) and best-of-two walk distances (r = 0.67 vs r = 0.58, P = .04) better correlated with the change in maximal exercise capacity (ie, better validity). Additionally, the variance of change was 14% to 25% less for the average-of-two walk distances and 14% to 33% less for the best-of-two walk distances than the variance of change in the single walk distance, indicating better precision. Conclusions: Adding a second walk to the 6-min walk test significantly improves its performance in measuring response to a therapeutic intervention, improves the validity of COPD clinical trials, and would result in a 14% to 33% reduction in sample size requirements. Hence, it should be strongly considered by clinicians and researchers as an outcome measure for therapeutic interventions in patients with COPD.

Original languageEnglish (US)
Pages (from-to)1545-1552
Number of pages8
JournalChest
Volume142
Issue number6
DOIs
StatePublished - Dec 2012

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ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine
  • Cardiology and Cardiovascular Medicine

Cite this

Chandra, D., Wise, R. A., Kulkarni, H. S., Benzo, R. P., Criner, G., Make, B., Slivka, W. A., Ries, A. L., Reilly, J. J., Martinez, F. J., & Sciurba, F. C. (2012). Optimizing the 6-min walk test as a measure of exercise capacity in COPD. Chest, 142(6), 1545-1552. https://doi.org/10.1378/chest.11-2702