title: Reference Equation for Six Minute Walk Test in Healthy Western India Population.
abstract: BACKGROUND
  The Six Minute Walk Test (6MWT) is used to assess disease progression and survival in chronic cardiopulmonary disorders. However, variability is noted in the six minute walk test distance (6MWD) in different populations.
  
  
  OBJECTIVE
  We aimed to develop a reference equation for 6MWD in healthy Western India population and compare the results with previously published Indian and Caucasian reference equations.
  
  
  METHODS
  Total 174 healthy subjects between 25 to 75 years performed the 6MWT. Variables assessed were age, height, weight, body mass index and sex. Predicted equations were derived using multiple linear regression and compared with the equations for North Indian male, South Indian and Caucasian population using Bland - Altman method.
  
  
  RESULTS
  The 6MWD mean (SD) was 512.38 (67.84) m for men and 457.27 (56.75) m for women with p=0.001. The 6MWD correlated with age (r=-0.44), height (r=0.43), weight (r=0.21) in univariate analysis. Stepwise multiple regression analysis showed age and sex to be independent predictors of 6MWD, R(2) =0.307. The reference equation for healthy Western India population is 553.289 + (-2.11 x age) + (45.323 x sex; men=1 and women =0). Bland Altman analysis showed that the mean bias was 50.87m (95% limits of agreement 134.77 to - 33.0) for North Indian male equation, 50.75m (95% limits of agreement 105.72 to - 4.22) for South Indian equation and 122.72m (95%limits of agreement 254.11 to - 8.67) for Enright and Sherrill's equation.
  
  
  CONCLUSIONS
  The North Indian male, South Indian and Caucasian equations significantly over-estimated the predicted walk distance for our healthy population. Hence, there is a need to develop subgroup population specific reference equations.
authors.affiliation: Professor, Department of Pulmonary Medicine, Goa Medical College , Goa, India .
authors.forename: Lalita
authors.initials: L
authors.lastname: Fernandes
authors.affiliation: Professor and HOD, Department of Pulmonary Medicine, Goa Medical College , Goa, India .
authors.forename: Anthony Menezes
authors.initials: AM
authors.lastname: Mesquita
authors.affiliation: Registrar, Critical Care Unit, Apollo Hospital , Chennai, India .
authors.forename: Rohit
authors.initials: R
authors.lastname: Vadala
authors.affiliation: Assistant Professor, Department of Preventive and Social Medicine, Goa Medical College , Goa, India .
authors.forename: Amit
authors.initials: A
authors.lastname: Dias
keywords: Anthropometry; Exercise test; Physiology; Reference values; Six minute walk distance; Walking