Relationship of Echocardiographic Z Scores Adjusted for Body Surface Area to Age, Sex, Race, and Ethnicity

Abstract

Background Published nomograms of pediatric echocardiographic measurements are limited by insufficient sample size to assess the effects of age, sex, race, and ethnicity. Variable methodologies have resulted in a wide range of Z-scores for a single measurement. This multicenter study sought to determine Z-scores for common measurements adjusted for body surface area (BSA) and stratified by age, sex, race, and ethnicity. Methods and Results Data collected from healthy non-obese children ≤18 years old at 19 centers with a normal echocardiogram included age, sex, race, ethnicity, height, weight, echocardiographic images, and measurements performed at the Core Laboratory. Z-score models involved indexed parameters (X/BSAα) that were normally distributed without residual dependence on BSA. The models were tested for the effects of age, sex, race, and ethnicity. Raw measurements from models with and without these effects were compared, and <5% difference was considered clinically insignificant because interobserver variability for echocardiographic measurements are reported as ≥5% difference. Of the 3566 subjects, 90% had measurable images. Appropriate BSA transformations (BSAα) were selected for each measurement. Multivariable regression revealed statistically significant effects by age, sex, race, and ethnicity for all outcomes, but all effects were clinically insignificant based on comparisons of models with and without the effects, resulting in Z-scores independent of age, sex, race, and ethnicity for each measurement. Conclusions Echocardiographic Z-scores based on BSA were derived from a large, diverse, and healthy North American population. Age, sex, race, and ethnicity have small effects on the Z-scores that are statistically significant but not clinically important.

Lean body mass is the strongest anthropometric predictor of left ventricular mass in the obese paediatric population

“…27 It is possible that future studies could utilise a newly derived multicentre database of normal echocardiograms that measured left ventricular mass similar to the current study to answer these questions. 28…”

Normal right and left ventricular volumes prospectively obtained from cardiovascular magnetic resonance in awake, healthy, 0- 12 year old children

“…Each method has cited literature supporting its application [29,30], thus it is important for the imager to understand which study to use for accurate z score generation based on their contouring method [28]. Generally speaking, our model differs from the Lopez et al Pediatric Heart Network echo paper [11], in that we found a linear relationship between BSA and cardiac chamber size, whereas they developed a model based upon a ratio estimator indexed to BSA raised to a fitted power. In addition, we found a constant sex difference, indicating modestly larger chamber sizes in males across all age groups.…”

“…Others have published smaller series of niche measurements of pediatric cardiac structures, including Doppler assessments of valves, left ventricular (LV) mass [7] and coronary artery dimension [8,9], as well as z scores for cardiac structures in the developing fetus [10]. Most recently, and most comprehensively, Lopez et al published the most robust set of 2D echocardiography measurements that describe normal growth in children over a wide range of BSA, ages and ethnicities [11]. Z scores gauging the relative size of a cardiac structure in children are valuable to the cardiac imaging community, as well as the larger pediatric cardiology and cardiothoracic surgery community to provide standards for decision-making regarding interventions and for the evaluation of outcomes.…”

Challenges and lessons learned from the Pediatric Heart Network Normal Echocardiogram Database study

“…The design and main results of the Pediatric Heart Network Normal Echocardiogram Database Study were previously published. 1 Briefly, the database was a retrospective collection of demographic and echocardiographic data obtained from healthy North American children ⩽18 years old from 19 congenital cardiac centres (10 Pediatric Heart Network core centres and 9 auxiliary centres) between April, 2013 and October, 2015. The targeted enrolment for the study included 3600 participants, divided into 36 groups, stratified by age (6 groups), race (White, African-American, Other), and gender, with ⩾80% of echocardiograms submitted expected to have all the necessary images to allow for a minimum of 80 echocardiograms per group to be analysed based on power calculations.…”

“…The goal was to develop a robust z-score database that accounted for age, race, and gender. 1 The study aimed to overcome limitations of previous echocardiographic z-score databases, including small sample size from single institutions, non-standardised methods for performing and normalising measurements, and limited assessment of the potential effects of race and gender. Despite the detailed study design and considerable time spent planning the study, we encountered unexpected challenges in its implementation.…”