ROC Generated Thresholds for Field-Assessed Aerobic Fitness Related to Body Size and Cardiometabolic Risk in Schoolchildren

 Objectives:1. to investigate whether 20 m multi-stage shuttle run performance (20mSRT), an indirect measure of aerobicfitness, could discriminate between healthy and overweight status in 9–10.9 yr old schoolchildren using Receiver OperatingCharacteristic (ROC) analysis; 2. Investigate if cardiometabolic risk differed by aerobic fitness group by applying the ROC cutpoint to a second, cross-sectional cohort.Design:Analysis of cross-sectional data.Participants:16,619 9–10.9 year old participants from SportsLinx project and 300 11–13.9 year old participants from theWelsh Schools Health and Fitness Study.Outcome Measures:SportsLinx; 20mSRT, body mass index (BMI), waist circumference, subscapular and superilliac skinfoldthicknesses. Welsh Schools Health and Fitness Study; 20mSRT performance, waist circumference, and clusteredcardiometabolic risk.Analyses:Three ROC curve analyses were completed, each using 20mSRT performance with ROC curve 1 related to BMI,curve 2 was related to waist circumference and 3 was related to skinfolds (estimated % body fat). These were repeated forboth girls and boys. The mean of the three aerobic fitness thresholds was retained for analysis. The thresholds weresubsequently applied to clustered cardiometabolic risk data from the Welsh Schools study to assess whether risk differed byaerobic fitness group.Results:The diagnostic accuracy of the ROC generated thresholds was higher than would be expected by chance (allmodels AUC.0.7). The mean thresholds were 33 and 25 shuttles for boys and girls respectively. Participants classified as ‘fit’had significantly lower cardiometabolic risk scores in comparison to those classed as unfit (p,0.001).Conclusion:The use of the ROC generated cut points by health professionals, teachers and coaches may provide theopportunity to apply population level ‘risk identification and stratification’ processes and plan for ‘‘at-risk’’ children to bereferred onto intervention services.