Six-minute-walk test in chronic obstructive pulmonary disease: Minimal clinically important difference for death or hospitalization

Michael I. Polkey, Martijn A. Spruit, Lisa D. Edwards, Michael L. Watkins, Victor Pinto-Plata, Jørgen Vestbo, Peter M.A. Calverley, Ruth Tal-Singer, Alvar Agustí, Per S. Bakke, Harvey O. Coxson, David A. Lomas, William MacNee, Stephen Rennard, Edwin K. Silverman, Bruce E. Miller, Courtney Crim, Julie Yates, Emiel F.M. Wouters, Bartolome Celli

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Abstract

Rationale: Outcomes other than spirometry are required to assess nonbronchodilator therapies for chronic obstructive pulmonary disease. Estimates of the minimal clinically important difference for the 6-minute-walk distance (6MWD) have been derived from narrow cohorts using nonblinded intervention. Objectives: To determine minimum clinically important difference for change in 6MWD over 1 year as a function of mortality and first hospitalization in an observational cohort of patients with COPD. Methods:Data fromtheECLIPSEcohortwereused(n=2,112).Death or first hospitalizationwere indexevents;wemeasured change in6MWDin the 12-month period before the event and related change in 6MWD to lungfunctionandSt. George'sRespiratoryQuestionnaire (healthstatus). Measurement and Main Results: Of subjects with change in the 6MWD data, 94 died, and 323 were hospitalized. 6MWD fell by 29.7 m (SD, 82.9 m) more among those who died than among survivors (P<0.001). A reduction in distance of more than 30 m conferred a hazard ratio of 1. 93(95%confidenceinterval, 1.29-2.90;P= 0.001) for death. No significant difference was observed for first hospitalization. Weak relationships only were observed with change in lung function or health status. Conclusions: A reduction in the 6MWD of 30 m or more is associated withincreased riskofdeath butnot hospitalizationdueto exacerbation in patientswith chronic obstructive pulmonary disease and represents a clinically significantminimally important difference.

Original languageEnglish (US)
Pages (from-to)382-386
Number of pages5
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume187
Issue number4
DOIs
Publication statusPublished - Feb 15 2013

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Keywords

  • 6MW
  • COPD
  • Death
  • Hospitalization
  • MCID

ASJC Scopus subject areas

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

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