title: Inaccuracy of estimating peak work rate from six-minute walk distance in patients with COPD.
abstract: BACKGROUND
  The cardiopulmonary exercise test (CPET) and the 6-minute walk test (6MWT) are used to prescribe the appropriate training load for cycling and walking exercise in patients with chronic obstructive pulmonary disease (COPD). The primary aims were: (i) to compare estimated peak work rate (Wpeak(estimated)) derived from six existing Wpeak regression equations with actual peak work rate (Wpeak(actual)); and (ii) to derive a new Wpeak regression equation using six-minute walk distance (6MWD) and conventional outcome measures in COPD patients.
  
  
  METHODS
  In 2906 patients with COPD, existing Wpeak regression equations were used to estimate Wpeak using 6MWD and a new equation was derived after a stepwise multiple regression analysis.
  
  
  RESULTS
  The 6 existing Wpeak regression equations were inaccurate to predict Wpeak(actual) in 82% of the COPD patients. The new Wpeak regression equation differed less between Wpeak(estimated) and Wpeak(actual) compared to existing models. Still, in 74% of COPD patients Wpeak(estimated) and Wpeak(actual) differed more than (±) 5 watts.
  
  
  CONCLUSIONS
  In conclusion, estimating peak work load from 6MWD in COPD is inaccurate. We recommend assessment of Wpeak using CPET during pre-rehabilitation assessment in addition to 6MWT.
authors.affiliation: Program Development Centre, CIRO+, Centre of Expertise for Chronic Organ Failure, Horn, The Netherlands. mauricesillen@ciro-horn.nl
authors.forename: Maurice J H
authors.initials: MJ
authors.lastname: Sillen
authors.forename: Jan H
authors.initials: JH
authors.lastname: Vercoulen
authors.forename: Alex J
authors.initials: AJ
authors.lastname: van 't Hul
authors.forename: Peter H C
authors.initials: PH
authors.lastname: Klijn
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
authors.forename: Dirk
authors.initials: D
authors.lastname: van Ranst
authors.forename: Jeannette B
authors.initials: JB
authors.lastname: Peters
authors.forename: Anton R J
authors.initials: AR
authors.lastname: van Keimpema
authors.forename: Frits M E
authors.initials: FM
authors.lastname: Franssen
authors.forename: Henk J A M
authors.initials: HJ
authors.lastname: Otten
authors.forename: Johan
authors.initials: J
authors.lastname: Molema
authors.forename: Jerôme J
authors.initials: JJ
authors.lastname: Jansen
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Spruit
mesh_terms: D000368:Aged; D005080:Exercise Test / Q000379:methods* / Q000706:statistics & numerical data*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation; D015203:Reproducibility of Results; D016138:Walking