Methods Percent Predicted Value for the 6-Minute Walk Test: Using Norm-Referenced Equations to Characterize Severity in Persons With CHF KONSTANTIN BALASHOV, BSc, 1 DEBBIE EHRMANN FELDMAN, PhD, 1,2 SYLVIE SAVARD, MPs, 3 STE ´ FANIE HOUDE, MD, MSc, 8 MARC FRENETTE, MD, 4 ANIQUE DUCHARME, MD, MSc, 5 NADIA GIANNETTI, MD, 6 CAROLINE MICHEL, MD, 7 AND LOUISE PILOTE, MD, PhD 3 Montreal, Canada; British Columbia, Canada ABSTRACT Background: The 6-minute walk test (6MWT) is a widely used measure of functional capacity in patients with chronic heart failure (CHF). Norm-referenced equations that predict the 6-minute walk distance (6MWD) according to age, height, weight, and gender have been proposed for healthy patients. We explored whether these equations apply to CHF patients. Methods and Results: The sample consisted of 213 patients newly admitted to specialized CHF clinics in Montreal, Canada. Percent predicted value (PPV) for 6MWD was calculated using norm-referenced equa- tions. We explored correlations between different measures: PPV, 6MWD, Minnesota Living with Heart Fail- ure Quality of Life score (MLHF-QOL). We compared severity among different age, gender, and BMI (body mass index) subgroups and assessed consistency using different measures of severity. Mean age was 65.5 years and 77.5% were men. Compared with the 6MWD, PPV had a slightly better correlation with MLHF-QOL score (0.26 versus 0.20), and slightly more predictive power in linear regressions (adjusted r 2 5 6.5% versus 4.2%). When PPV was used to differentiate severity between different age, gender, and BMI subgroups, it consistently led to similar conclusions as the MLHF-QOL score, unlike 6MWD. Conclusion: The 6MWD in meters may give misleading results when used as an indicator of severity of CHF condition to compare groups with different sex, age, and BMI distributions. It may be necessary to standardize it using norm-referenced equations. (J Cardiac Fail 2008;14:75e81) Key Words: The 6-minute walk test, functional capacity, norms. It is necessary to use functional testing for patients with chronic heart failure (CHF) to estimate their prognosis and plan effective treatment strategies. Therefore a test that is ac- curate, reproducible, safe, and inexpensive is required. The maximal peak oxygen consumption test meets some of these criteria, but has several important limitations. 1,2 First, most patients with CHF lead a sedentary lifestyle and therefore measurement of peak oxygen consumption may not reflect their true functional limitation during daily activities. Sec- ond, a significant proportion of these patients cannot perform the test because of comorbidities or technical prob- lems. For example, some patients are unable to tolerate the mouthpiece of the gas analyzer. Finally, this test requires specialized equipment and expertise and thus is not available for the assessment of a vast proportion of CHF patients. 2 The 6-minute walk test (6MWT) can be performed by most patients, without the need for specialized equipment. 2 The 6MWT was first used by Guyatt et al in 1985 3 and From the 1 University of Montreal, School of Rehabilitation; 2 Centre de Recherche Interdisciplinaire en Re ´adaptation; 3 Division of Clinical Epide- miology, McGill University Health Centre; 4 Ho ˆpital Sacre ´-Cœur de Mon- tre ´al; 5 Montreal Heart Institute, University of Montreal; 6 Royal Victoria Hospital, McGill University Health Centre; 7 SMBD Jewish General Hospi- tal, Montreal, Canada; and 8 Kootenay Boundary Regional Hospital, Trail, British Columbia, Canada. Manuscript received April 13, 2007; revised manuscript received July 15, 2007; revised manuscript accepted September 10, 2007. Reprint requests: Dr. Debbie Ehrmann Feldman, Universite ´ de Montre ´al, E ´ cole de readaptation, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec, Canada H3C 3J7. Supported by a grant from the Canadian Institutes of Health Research (CIHR). Mr. Balashov was the recipient of a research bursary from University of Montreal. Dr. Feldman holds a new investigator career award from The Ar- thritis Society. Dr. Pilote holds an investigator career award from CIHR. Dr. Ducharme is supported by ‘‘Fond de la Recherche en Sante ´ du Que ´bec’’ (FRSQ). 1071-9164/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.cardfail.2007.09.005 75 Journal of Cardiac Failure Vol. 14 No. 1 2008