Z Scores for Pediatric Echocardiography Dimensions Adjusted for Body Size, BMI, and Age

BACKGROUND: Cardiovascular dimensions measured during pediatric echocardiograms must be normalized for body size. However, other variables may confound their interpretation, such as age and abnormal body habitus. This retrospective cross-sectional study of the Canadian Congenital and Pediatric Cardiology Research Network aimed to create Z score equations for commonly measured dimensions in pediatric 2-dimensional echocardiography that were free of residual confounding effects of body size, body mass index, and age. METHODS: The reference sample consisted of >20 000 children without heart disease from 9 institutions who underwent clinical echocardiography that was reported as normal. A generalized additive model for location, scale, and shape (GAMLSS) was used to model the expected distributions of measurements as a function of sex, height, weight, body mass index, and age. RESULTS: Compared with a model that only considered body surface area, the proposed Z scores demonstrated less bias in subgroups of overweight, young, and early school-aged children. CONCLUSIONS: The proposed Z score equations may improve diagnostic and therapeutic accuracy by ensuring that body size, body mass index, and age do not confound the interpretation of measurements.