Application of body mass index according to height-age in short and tall children.
BACKGROUND
In children with either delayed or accelerated growth, expressing the body mass index (BMI) to chronological age might lead to invalid body composition estimates. Reference to height-age has been suggested for such populations; however its validity has not been demonstrated.


METHODS
Anthropometric data of healthy children were obtained from the German KiGGS survey. We selected three samples with different height distributions representing short stature (mean height SDS: -1.6), normal stature (height SDS: 0), and tall stature (height SDS: +1.6), and compared BMI-for-age and BMI-for-height-age between these samples across the paediatric age range. Differences between samples were tested using Kruskal-Wallis one-way analysis of variance and permutation tests.


RESULTS
At a given age, BMI was distributed towards lower values in short, and towards higher values in tall subjects as compared to a population with average height distribution. Expressing BMI to height-age eliminated these differences in boys with a short stature from 4 years to 14 years of age, in tall boys from 4 to 16 years, in short girls aged 2-10 years or tall girls aged 2-17 years.


CONCLUSIONS
From late infancy to adolescent age, BMI distribution co-varies with height distribution and referencing to height-age appears appropriate within this age period. However, caution is needed when data about pubertal status are absent.
European Registry for Paediatric Nephrology/ERA-EDTA Registry, Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Marjolein
M
Bonthuis
Kitty J
KJ
Jager
Ameen
A
Abu-Hanna
Enrico
E
Verrina
Franz
F
Schaefer
Karlijn J
KJ
van Stralen
D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D001823:Body Composition / Q000502:physiology*; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results