Performance on the iSTEP and 10 m-ISWT in boys with haemophilia

Boys with haemophilia (BwH) have improved health outcomes. Measures of physical function in haemophilia are not challenging or sensitive enough to reflect physical limitations or guide rehabilitation. To identify meaningful tests, we aimed to: evaluate the performance of BwH on two physical performance measures: iSTEP and 10 m-ISWT; identify factors which predict performance and compare BwH to their unaffected peers.

BwH completed both iSTEP and 10 m-ISWT. Disease severity, age, BMI, HJHS, lower limb muscle torque, time spent in moderate to vigorous physical activity, sedentary time, were included as factors to predict performance. Results were compared to unaffected peers.

43 boys median age 10 (10 mild/moderate, 26 severe, 7 inhibitors) were recruited. BwH were less likely to complete the iSTEP and performed less well on the 10 m-ISWT than age matched peers. Ceiling effects were apparent for iSTEP, but not the 10 m-ISWT test. Age was the only significant predictor for performance in the iSTEP, with older boys being more likely to achieve a higher level or complete the test. Greater age, lower BMI, milder disease severity and more time spent in MVPA all predicted better performance on the 10 m-ISWT, with BMI and habitual physical activity a potential rehabilitation focus for underperforming individuals. HJHS and muscle strength did not predict performance on either test.

Despite the space need to conduct the 10 m-ISWT, it appears to be a superior performance measure than the iSTEP in BwH and provides clinically meaningful information, which can be interpreted using age-specific normative reference equations.