Reference values and equations for the 6-minute walk distance of Nigerian children aged 6-11 years: A cross-sectional study.

BACKGROUND

The 6-minute walk test (6MWT), a simple, reliable, and valid test that uses the distance walked in 6 minute walk distance (6MWD) to quantify functional capacity, is widely used in the management of chronic disorders. However, the absence of reference standards from sub-Saharan African, including Nigerian, school-aged children limits its utility in this age group.

OBJECTIVES

To develop normative values and equations for the 6MWD of school-aged Nigerian children.

METHODS

In a cross-sectional study, healthy children aged 6-11 years in Lagos, Nigeria, completed the 6MWT on 20-m-long straight outdoor courses in their schools. The primary outcome was the 6MWD in meters while potential predictors included demographic (age, sex), anthropometric (height, weight, chest circumference, leg length) and physiologic variables (pre-walk, immediate post-walk, and fifth min-post-walk heart rate [HR], oxygen saturation [SpO ], systolic blood pressure [SBP], diastolic blood pressure [DBP], and rating of perceived exertion [RPE]; and the difference between pre-walk and post-walk HR [∆HR], SpO [∆SpO ], SBP [∆SBP], DBP [∆DBP], and RPE [∆RPE]).

RESULTS

Overall, 627 pupils (52.1% girls) walked 504.6 ± 66.6 m (95% CI: 499.4, 509.8; range: 326.6-673.0 m); 16 m longer in boys (p = 0.002). A stepwise linear regression model yielded: 6MWD (m) = 347.9 + 14(Age ) + 1.6 (∆HR ) + 17.6(Sex ) + 1.2(∆SBP ); R  = 0.25. Previously published reference equations mostly over-estimated Nigerian children's 6MWD.

CONCLUSION

These reference standards add to the global normative data on pediatric 6MWT and may be useful for the functional evaluation of Nigerian school-aged children with chronic childhood disorders.