ESPE Yearbook of Paediatric Endocrinology

J Pediatr. 2021 Mar 5;S0022-3476(21)00211-0. https://pubmed.ncbi.nlm.nih.gov/33676932/

The authors analysed BMI data from 10.8 million children and adolescents from the PEDSnet database (USA), collected longitudinally between 1999-2019, to examine the tracking of various BMI metrics (BMIz, BMImz, BMIz extended, %BMIp95, %BMIp50,%BMIp50 adjusted| calculated according to CDC growth charts). The strength of this evaluation is that the tracking of BMI metrics was examined in an enormous cohort. The most important finding was that the tracking of BMIz was lower than for all other BMI metrics in children with obesity as well as for children with extreme obesity (BMI≥140% of the 95th percentile at baseline).

This study clearly shows the influence of the applied BMI metrics on the longitudinal BMI course or on the effect of an intervention on BMI in obese children and adolescents. These results are consistent with other literature, in which the use of BMIz in obese children and adolescents in the assessment of the degree of obesity and the effects of an intervention has already been critically discussed (1, 2, 3, 4, 5). Clinicians and researchers should familiarize themselves with the calculation and interpretation of alternatives to BMIz (e.g. %BMIp95, %BMIp50), as they appear to be more suitable for assessing BMI progression (with or without intervention) in obese children and adolescents.

References: 1. Flegal KM, Wei R, Ogden CL, Freedman DS, Johnson CL, Curtin LR. Characterizing extreme values of body mass index-for-age by using the 2000 Centers for Disease Control and Prevention growth charts. Am J Clin Nutr 2009;90:1314-20.2. Woo JG. Using body mass index Z-score among severely obese adolescents: a cautionary note. Int J Pediatr Obesity 2009;4:405–10.3. Freedman DS, Butte NF, Taveras EM, Lundeen EA, Blanck HM, Goodman AB, et al. BMI z-Scores are a poor indicator of adiposity among 2- to 19-year-olds with very high BMIs, NHANES 1999–2000 to 2013–2014. Obesity (Silver Spring) 2017;25:739–46.4. Freedman DS, Butte NF, Taveras EM, Goodman AB, Ogden CL, Blanck HM. The limitations of transforming very high body mass indexes into z-scores among 8.7 million 2- to 4-year-old children. J Pediatr 2017;188:50–6.5. Kelly AS, Daniels SR. Rethinking the use of body mass index z-score in children and adolescents with severe obesity: time to kick it to the curb? J Pediatr 2017;188:7–8.