Can peak work rate predict peak oxygen uptake in children with juvenile idiopathic arthritis?

Abstract

To examine whether peak work rate (W(peak)) can predict peak oxygen uptake (VO(2peak)) in children with juvenile idiopathic arthritis (JIA). Ninety-one patients with JIA with a mean +/- SD age of 11.4 +/- 2.9 years underwent a cardiopulmonary exercise test in which VO(2peak) and W(peak) were determined. A multivariate regression model was used to formulate a regression equation to predict VO(2peak) using W(peak) and anthropometric and demographic details. This regression equation was subsequently cross-validated using an unrelated data set from children with JIA (n = 17). The following linear regression equation to predict VO(2peak) was established: VO(2peak) (liters/minute) = 0.308 + 0.146 x sex (0 = female, 1 = male) + 0.005 x weight (kg) + 0.008 x W(peak) (W) (R(2) = 0.91, standard error of the estimate = 0.18 liter/minute). Using this equation, the predicted VO(2peak) was strongly related to the measured VO(2peak) (r = 0.96, P < 0.0001). Bland and Altman analysis revealed a mean difference of 0.01 liter/minute and limits of agreement between -0.35 and 0.35 liter/minute. This study suggests that W(peak) is a strong predictor of VO(2peak) in children with JIA and may be used as a surrogate measure of VO(2peak) in situations where it is not possible to formally assess VO(2peak).