Waist-to-height ratio, body mass index, and cardiovascular risk profile in children with chronic kidney disease

Abstract

Background: Cardiovascular (CV) risk is high in children with chronic kidney disease (CKD), and further compounded in those who are overweight. Children with CKD have a unique body habitus not accurately assessed by body mass index (BMI). Waist-to-height ratio (WHr), a better predictor of CV risk in populations with short stature, has not been investigated in children with CKD.

Methods: Analysis of 1723 visits of 593 participants enrolled in the Chronic Kidney Disease in Children (CKiD) study was conducted. CKiD participants had BMI and WHr measured and classified as follows: (1) lean (WHr ≤ 0.49, BMI < 85th percentile); (2) WHr-overweight (WHr > 0.49, BMI < 85th percentile); (3) BMI-overweight (WHr ≤ 0.49, BMI ≥ 85th percentile); or (4) overweight by both BMI and WHr. Left ventricular mass index (LVMI), fasting lipids, fibroblast growth factor 23 (FGF23), blood pressure, and glucose were measured as markers of CV risk. Linear mixed-effects regression was used to evaluate differences in CV markers between overweight and lean groups.

Results: Participants were 12.2 years old, 60% male, and 17% African-American. Approximately 15% were overweight by WHr but not by BMI. Overweight status by WHr-only or both WHr and BMI was associated with lower high-density lipoprotein (HDL) and higher LVMI, triglycerides, and non-HDL cholesterol compared to lean. CV markers of participants overweight by BMI-only were similar to those of lean children.

Conclusions: WHr-adiposity is associated with an adverse CV risk profile in children with CKD. A significant proportion of children with central adiposity are missed by BMI. WHr should be utilized as a screening tool for CV risk in this population.

Keywords: Body mass index; Dyslipidemia; Fibroblast growth factor 23; Hypertension; Left ventricular mass index; Obesity.

Conflict of interest statement

Conflict of Interest: none declared

Figures

Figure 1.. Distribution of weight status by study visit

The distribution of WHr and BMI z-scores are plotted over all study visits (n=1723) and weight classified as lean (WHr≤0.49, BMI th percentile), WHr overweight only (WHr >0.49, BMI <85th percentile), BMI-overweight only (WHr ≤0.49, BMI ≥85th percentile), or overweight by both BMI and WHr (WHr >0.49, BMI ≥85th percentile).

FIGURE 2.. Distribution of CV markers by weight status

CV markers (median and IQR) are illustrated by weight classification. Overweight by WHr-only, BMI-only, and combined (overweight by both WHr and BMI) groups are shown in the white, light gray, and dark gray bars, respectively, overlaying a shaded gray box representing the lean group. Due to the longitudinal nature of the data, bivariate statistical tests of significance were not appropriate; this figure represents a descriptive presentation of the data only.