Background: The 6-min walk test (6MWT) is a submaximal exercise test used to assess functional status in patients with cardiopulmonary diseases. Regression equations have previously been published as a normal reference for 6-min walk distance (6MWD) in healthy Caucasian adults. However, a recent study showed that the normal predicted 6MWD could differ among ethnic populations. The aim of this study was: (1) to determine the normal 6MWD in a sample of healthy Saudi adults; (2) to create a regression equation for the established 6MWD; and (3) to compare the 6MWD in the present study with previously published equations.
Method: The 6MWT was administered to 298 healthy volunteers (53% males) between the ages of 16 and 50 years.
Result: The average 6MWD was 409+/-51 m, with longer distances walked by males (429+/-47 m) than by females (386+/-45 m) (p<0.001). The regression equation revealed that height (p<0.001) and age (p=0.034) were the most significant predictors of distance (6MWD=(2.81 x height)+(0.79 x age)-28.5). In addition, the equation explained 25% of the distance variance. All previously published equations overestimated the Saudi 6MWD by 109-340 m.
Conclusion: Saudi populations have significantly shorter 6MWDs than those reported for other ethnic groups. Thus, the Caucasian reference value for the 6MWD should not be used in Saudi subjects, as it overestimates the distance and may interfere with the therapeutic and prognostic value of the test.