Prediction equations for 6-minute walk distance in apparently healthy Nigerians

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 [SpO₂ ], 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], SpO₂ [∆SpO₂ ], 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_years ) + 1.6 (∆HR_beats/min ) + 17.6(Sex_{male=1, female=0} ) + 1.2(∆SBP_mmHg ); R²  = 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.

Reference values and regression equations for predicting the 6-minute walk distance in Saudi adults aged 50-80 years: A cross- sectional study

BACKGROUND

The 6-minute walk test (6-MWT) is commonly used to measure functional capacity in clinical and research settings. The reference equations for predicting the 6-minute walk distance (6-MWD) in different populations have been established; however, there is a lack of information regarding healthy Saudi individuals over 50 years old.

OBJECTIVES

This study aimed to establish the reference values of 6-MWD in a sample of healthy Saudi adults aged 50-80 years, develop regression equations for the established 6-MWD, and compare the measured 6-MWD in the present study with the predicted 6-MWD derived from the previously published regression equations.

METHODS

In total, 210 healthy Saudi volunteers aged 50-80 years participated in this cross-sectional study. The 6-MWT was performed according to the American Thoracic Society (ATS) guidelines. Lung function, physical activity, blood pressure, heart rate, oxygen saturation, exertion level of leg fatigue, and sensation of dyspnea were measured.

RESULTS

The mean 6-MWD was 396.2 ± 69.4 m. It was significantly correlated with age, sex, height, body mass index (BMI), and physical activity. The predictors of 6-MWD were age and BMI for men, while they were age, BMI, and height for women. They accounted for 25% and 35% of the total variance of 6-MWD for men and women, respectively. The measured 6-MWD was significantly shorter than the predicted 6-MWD.

CONCLUSION

Saudi populations have significantly shorter 6-MWDs than those reported in other ethnic groups. The sex-specific equations developed in this study are expected to provide a useful measure of 6-MWT for Saudi adults. However, further investigation is required to validate the application of these equations to individuals living in different regions of Saudi Arabia.

Limitations of 6-minute walk test reference values for spinal muscular atrophy

INTRODUCTION

The 6-minute walk test (6MWT) is a well-established clinical assessment of functional endurance, validated as a measure of walking ability in spinal muscular atrophy (SMA). The current availability of disease-modifying therapies for SMA indicates a growing need for normative reference data to compare SMA patients with healthy controls.

METHODS

The literature was searched in two scientific databases. Studies were evaluated and selected based on adherence to American Thoracic Society guidelines for administering the 6MWT. Reference equations from the selected studies were applied to 6MWT data collected from SMA patients to calculate and compare % predicted values.

RESULTS

Three pediatric and six adult studies were selected for comparison. The % predicted values using the pediatric and adult equations ranged from 47.7 ± 18.2% to 67.6 ± 26.2% and 43.0 ± 17.9% to 59.5 ± 26.2%, respectively, and were significantly different (P < 0.001).

DISCUSSION

Results suggest significant variability between % predicted values derived from published reference equations in children and adults, despite adherence to 6MWT standardization.