title: Predicting outcomes from 6-minute walk distance in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Exercise tolerance is an important clinical aspect of chronic obstructive pulmonary disease that can be easily and reliably measured with the 6-minute walking test (6MWT). To improve the utility of the 6MWT for patient and health care system management, the interpretation of the functional status measure in relation to death and hospitalization should be elucidated.
  
  
  METHODS
  Three-year, prospective, multicenter observational study to evaluate the predictive power of 6MWD for death or exacerbation-related hospitalization and to evaluate the factors that help determine 6MWD.
  
  
  RESULTS
  We measured 6MWD at baseline and annually in 2110 patients with clinically stable Global Initiative for Obstructive Lung Disease (GOLD) stage II-IV COPD and recorded exacerbation-related hospitalizations and all-cause mortality. During the study, 200 patients died and 650 were hospitalized. Using receiver operating characteristics, the best predictive thresholds of the 6MWD were 334 m for increased risk of death and 357 m for exacerbation-related hospitalization (area under the curve 0.67 and 0.60 respectively); however, the discriminatory thresholds, especially for mortality, were influenced by age. The mean (SE) 6MWD declined by 1.6 (1.2) m per year in GOLD II, 9.8 (1.3) m per year in GOLD III, and 8.5 (2.4) m per year in GOLD IV.
  
  
  CONCLUSIONS
  The 6MWD provides prognostic information that may be useful for identifying high-risk patients with COPD.
authors.affiliation: Program Development Centre, CIRO+, Horn, The Netherlands. martijnspruit@ciro-horn.nl
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Spruit
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.forename: Bartolome
authors.initials: B
authors.lastname: Celli
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Edwards
authors.forename: Michael L
authors.initials: ML
authors.lastname: Watkins
authors.forename: Victor
authors.initials: V
authors.lastname: Pinto-Plata
authors.forename: Jørgen
authors.initials: J
authors.lastname: Vestbo
authors.forename: Peter M A
authors.initials: PM
authors.lastname: Calverley
authors.forename: Ruth
authors.initials: R
authors.lastname: Tal-Singer
authors.forename: Alvar
authors.initials: A
authors.lastname: Agusti
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.forename: David A
authors.initials: DA
authors.lastname: Lomas
authors.forename: William
authors.initials: W
authors.lastname: MacNee
authors.forename: Stephen
authors.initials: S
authors.lastname: Rennard
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Courtney C
authors.initials: CC
authors.lastname: Crim
authors.forename: Julie
authors.initials: J
authors.lastname: Yates
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000401:mortality / Q000503:physiopathology*; D016138:Walking