Meaningful change in 6-minute walk in people with peripheral artery disease

Mary M. McDermott*, Lu Tian, Michael H. Criqui, Luigi Ferrucci, Michael S. Conte, Lihui Zhao, Lingyu Li, Robert Sufit, Tamar S. Polonsky, Melina R. Kibbe, Philip Greenland, Christiaan Leeuwenburgh, Jack M. Guralnik

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Objective: The 6-minute walk test is a common outcome measure in clinical trials of people with lower extremity peripheral artery disease (PAD). However, what constitutes a meaningful change in the 6-minute walk distance has not been well defined for people with PAD. The present study related the change in the 6-minute walk distance to the degree of participant-reported improvement or decline in the 6-minute walk distance to define a meaningful change in the 6-minute walk distance for those with PAD. Methods: Participants with PAD from three observational longitudinal studies completed the walking impairment questionnaire (WIQ) distance score and 6-minute walk at baseline and 1 year later. The WIQ distance score measures participants' perceived difficulty walking seven different distances without stopping (ranging from walking around the home to walking 5 blocks) on a 0 to 4 Likert scale, with 0 representing an inability to walk the distance and 4 representing no difficulty. The mean changes in the 6-minute walk distance corresponding to the participants' report of no change, 1-unit change, or 2-unit change, respectively, in the Likert scale score between the baseline and 1-year follow-up measures were calculated for each WIQ distance. Results: A total of 777 participants with PAD (mean age, 71.2 ± 8.8 years; mean baseline 6-minute walk distance, 350.1 ± 118.1 meters) completed 5439 questions about their difficulty walking each WIQ distance at baseline and follow-up. Participants with PAD who reported no change in their difficulty in walking each WIQ distance between baseline and follow-up had a decline of 7.2 meters (95% confidence interval [CI], −11.6 to −2.8 meters) in the 6-minute walk test. Relative to those reporting no change in difficulty walking, the participants reporting 1- and 2-point improvements in walking ability showed 6-minute walk distance improvements of 7.8 meters (95% CI, −0.3 to 15.9 meters) and 20.1 meters (95% CI, 1.1-39.2 meters), respectively. Relative to those reporting no change in walking difficulty, those reporting 1- and 2-point declines in perceived walking difficulty showed declines of −11.2 meters (95% CI, −19.0 to −3.4 meters) and −23.8 meters (95% CI, −37.4 to −10.3 meters) in the 6-minute walk distance. Conclusions: Among people with PAD, ∼8- and ∼20-meter improvements in the 6-minute walk distance represent small and large improvements in walking ability, respectively. People with PAD who reported no change in their ability to walk distances over 1 year simultaneously declined by a mean of 7 meters in the 6-minute walk test. These findings will be useful for interpreting the results from randomized trials of interventions to improve the walking performance of people with PAD.

Original languageEnglish (US)
JournalJournal of Vascular Surgery
DOIs
StateAccepted/In press - 2020

ASJC Scopus subject areas

  • Surgery
  • Cardiology and Cardiovascular Medicine

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    McDermott, M. M., Tian, L., Criqui, M. H., Ferrucci, L., Conte, M. S., Zhao, L., Li, L., Sufit, R., Polonsky, T. S., Kibbe, M. R., Greenland, P., Leeuwenburgh, C., & Guralnik, J. M. (Accepted/In press). Meaningful change in 6-minute walk in people with peripheral artery disease. Journal of Vascular Surgery. https://doi.org/10.1016/j.jvs.2020.03.052