Inaccuracy of Estimating Peak Work Rate from Six-Minute Walk Distance in Patients with COPD

M.J.H. Sillen, J.H. Vercoulen, A.J. van 't Hul, P.H.C. Klijn, E.F.M. Wouters, D. van Ranst, J.B. Peters, A.R.J. van Keimpema, F.M.E. Franssen, H.J.A.M. Otten, J. Molema, J.J. Jansen, M.A. Spruit

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Abstract Introduction. 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 (Wpeakestimated) derived from six existing Wpeak regression equations with actual peak work rate (Wpeakactual); 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 Wpeakactual in 82% of the COPD patients. The new Wpeak regression equation differed less between Wpeakestimated and Wpeakactual compared to existing models. Still, in 74% of COPD patients Wpeakestimated and Wpeakactual differed more than (+/-) 5 watts. Conclusion. 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.
Original languageEnglish
Pages (from-to)281-288
JournalCopd-Journal of Chronic Obstructive Pulmonary Disease
Issue number3
Publication statusPublished - 1 Jan 2012

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