Are Canadian pediatric nephrology patients really overweight?

To assess the influence of height age and short stature on BMI z-scores in children with chronic kidney disease (CKD) in view of the pandemic increase of childhood obesity.

Pediatric nephrology patients older than 2 years of age from 2 tertiary centers in Ontario and age- and gender matched controls from a local reference population.

We estimated height, weight and body mass index (BMI) z-scores of 705 nephrology patients (319 female) and 4,196 controls aged 2.01 - 19.92 years with chronological and height-adjusted age (corresponding age for a given height plotted on the 50th percentile). The National Health and Nutrition Examination Survey (NHANES III) was used for the z-score Estimation.

Chronological age-based patient weight z-scores were significantly heavier than in the NHANES data (median weight z-score +0.29, BMI z-score +0.51; significantly non-zero), not significantly different from height-adjusted age-based BMI z-score (+0.51). The children with kidney problems were shorter (-0.10 SD) than controls.

The proportion of overweight nephrology patients was similar to matched controls and BMI z-score diminished with worsening GFR.