Reference equation for 6-minute walk in individuals with Parkinson disease

Normal values, as well as determining factors, for the 6-minute walk test are available for nondisabled adults, but less is known about individuals with Parkinson disease (PD). This study created a PD-specific reference equation and identified unique factors associated with 6-minute walk distance (6MWD). Eighty individuals (mean +/- standard deviation [SD] age: 66.3 +/- 9.8 yr) with mild to moderate PD underwent a neurological examination and completed a small battery of tests to assess their balance confidence, fall risk, mobility, and balance. Their mean +/- SD 6MWD was 394.1 +/- 98.4 m (95% confidence interval: 370.0-418.1). Stepwise multiple regression analysis demonstrated that timed up-and-go (TUG) test, one-leg stance (OLS) test, and sex were significant independent contributors to 6MWD and accounted for 56.6% of the variance. The resulting PD-specific regression equation is 6MWD_pred = 543.06 + (-10.83 x TUG) + (2.04 x OLS) + (-44.44 x sex). (For sex, 0 = female, 1 = male.) Future interpretation of 6MWD in individuals with PD may be enhanced if expressed as a percentage of the value predicted utilizing this reference equation.