Is body mass index a useful measure of excess body fatness in adolescents and young adults with Down syndrome?

Abstract

Background To determine the validity of body mass index (BMI) to identify excess fatness in youth with Down syndrome (DS). Methods Using the CDC growth reference, we defined overweight (≥85th percentile) and obesity (≥95th percentile) based on participants’ age- and sex-specific BMI z-scores, calculated from measured height and weight. Percentage body fat (%BF) was measured by dual-energy X-ray absorptiometry. We determined sensitivity, specificity, positive predictive value, negative predictive value, and efficiency of BMI percentiles to identify excess adiposity relative to elevated %BF cut-offs developed from the Pediatric Rosetta Body Composition project (Freedman et al., 2009b) in 32 youth (20M/12F), ages 13–21 years with Down syndrome. Results For adolescents with Down syndrome using the cut-off points of 95th percentile for BMI (obesity), sensitivity and specificity were 71% and 96%, respectively. Positive predictive value was 83% and negative predictive value was 92%. Overall efficiency was 91%. Sensitivity and specificity for BMI cut-offs above the 85th percentile (overweight) were 100% and 60%, respectively. The positive predictive value was 41% and negative predictive value was 100%. Overall efficiency was 69%. Conclusion On the whole, the obesity (≥95th percentile) cut-off performs better than the overweight cut-off (85th–94th percentile) in identifying elevated fatness in youth with DS.

Obesity Prevention for Children with Developmental Disabilities

“…Children aged 2 to 20 are considered to be overweight when their BMI-for-age is greater than or equal to the 85 th percentile, and are classified as obese when BMI-for-age is at or above the 95 th percentile. Although these BMI cut-offs were developed for populations without disabilities, one study of adolescents with Down syndrome supports the validity of their use as indicators for overweight and obesity in that population [17]. Several other reference populations are in use around the world [18–20], including a WHO international reference [21].…”

Nutrition assessment and indicators of visceral fat and subcutaneous fat in children with Down syndrome

“…A similar result was found in youngsters from the USA with DS, where BMI was shown to be a good predictor of fat behaviour (71% sensitivity and 96% specificity). 8 We feel that these results are important because they make it possible to suggest that, for children and adolescents with DS, an assessment that includes all these indicators of overall nutritional status and fat compartment should be performed to identify children with DS with excess body fat.…”

“…5,7 That is the reason why some countries have developed growth cures for this population (USA, UK and Ireland). 8 A proposal for using the growth standards for Spanish children with DS, developed by the Fundación Catalana [Catalan Foundation], 2,9,10 is currently being discussed in Chile. These standards are considered as the most appropriate for the Chilean population, given that they were designed based on a Hispanic population; however, they have the important limiting factor of the absence of the weight/height (WHI) indicator or body mass index/age (BMIa).…”

Evaluación nutricional e indicadores de grasa visceral y subcutánea en niños con síndrome de Down

“…Al mismo tiempo el IMC/E e IP/T demostraron una correlación alta con la mayoría de los indicadores de masa grasa con excepción del PT que fue moderado. Resultado similar se encontró en jóvenes norteamericanos con SD donde se obtuvo que el IMC es un buen predictor del comportamiento graso (sensibilidad 71% y especificidad 96%) 8 . Creemos que estos resultados son importantes ya que nos permite sugerir que en los niños y adolescentes con SD se debe realizar una evaluación que comprenda todos estos indicadores de estado nutricional global y de compartimento graso para identificar a los niños con SD con exceso de adiposidad.…”

“…Es por este motivo que algunos países han desarrollado sus curvas de crecimiento en esta población (EE. UU., UK e Irlanda) 8 . En Chile actualmente se sugiere la utilización de los estándares de crecimiento de niños españoles con SD, desarrolladas por la Fundación Catalana 2,9,10 , ya que son consideradas como las más adecuadas para la población chilena, ya que fueron diseñadas a partir de la población latina, pero se encuentra con la gran limitante de la ausencia del indicador peso/talla (P/T) o índice masa corporal/edad (IMC/E).…”