Developing and validating equations to predict O peak from the 6MWT in Childhood ALL Survivors.

INTRODUCTION

The 6-Minute Walking Test (6MWT) is a safe, standardized and well utilized method to assess the functional capacity. Recently, it was reported that the published prediction equations cannot accurately predict a valid maximal oxygen consumption (V̇O peak) value in cancer survivors. Thus, the aim of this study was to establish and to validate a new equation based on the 6MWT to predict V̇O peak in childhood acute lymphoblastic leukemia (ALL) survivors.

METHODS

A total of 200 childhood ALL survivors were enrolled in this study, among which 168 participants underwent a cardiopulmonary exercise test and a 6MWT to assess their functional capacity and their cardiorespiratory fitness. In addition, participants completed a physical activity questionnaire. Participants were randomly divided in two groups to establish the equations ( = 118 (70%)) and to validate it ( = 50 (30%)). Multiple linear regression analyses were used to determine a new prediction equation for V̇O peak from 6MWT using clinical and specific variables related to the disease. The accuracy in between V̇O peak measured and V̇O peak predicted were assessed using the Bland and Altman method.

RESULTS

The new establish clinical V̇O peak equation is: V̇O peak (mL.kg.min) = (-0.283age(years)) - (0.099weight(kg)) + (0.0716MWD(meters)) -(0.135HR end(bpm)) + 22.789 with a mean bias of 2.67 mL.kg.min (95% CI (-9.64 to 14.98)). The new establish disease-specific V̇O peak equation is: V̇O peak (mL.kg.min) = (-0.236age(years)) - (0.094weight(kg)) -(0.120HR end(bpm)) + (0.0676MWD(meters)) + (0.065MVLPA(min/day)) - (0.204DT(years)) + 25.145 with a mean bias of 2.51 mL.kg.min (95% CI (-9.98 to 15.01)).

CONCLUSION

This is the first study that predicted V̇O peak from a 6MWT using clinical and specific variables related to the disease of childhood ALL survivors. The availability of these newly established V̇O peak equations makes them an accurate tool to provide a better follow-up and better adapted physical training for survivors. We invite researchers to use our assessment procedures for their further studies.IMPLICATIONS FOR REHABILITATIONIt is critical to understand the cardiorespiratory fitness of the childhood ALL survivorsThe maximal oxygen consumption (i.e., V̇O peak) is recognized as the gold standard to measure the patient's cardiorespiratory fitness in the field of exercise physiologyThis study is novel and reports the validation of two new VO peak equations, from 6MWT, by using clinical and disease-specific variables of childhood ALL survivorsThe availability of such validated equations can better facilitate the follow-up of survivors' cardiorespiratory fitness, by relevant health care professionals and exercise physiologists.