Relationship between childhood obesity cut-offs and metabolic and vascular comorbidities: comparative analysis of three growth standards.

BACKGROUND: To compare the association between metabolic and vascular comorbidities and the body mass (BMI)-for-age cut-off criteria from three growth standards [Centers for Disease Control and Prevention (CDC), 2000; World Health Organization (WHO), 2007; Spanish Reference Criteria (Carrascosa Lezcano et al., 2008)] that are used to define being overweight and obese in childhood.

METHODS: A prospective study was conducted in 137 children (aged 8-16 years). Based on BMI-for-age Z-scores according to WHO cut-offs, 59 participants were obese, 35 were overweight and 43 were normal-weight. All participating children were subsequently reclassified applying the CDC and Spanish Reference Criteria. Blood pressure (BP), biochemical variables and vascular parameters (stiffness and intima-media thickness) were analysed.

RESULTS: According to WHO and CDC references, 48% and 43% of the children, respectively, were categorised as obese, whereas 16% were considered as obese using the Spanish Reference Criteria. Applying WHO criteria, obese children showed significantly higher levels of insulin, homeostasis model assessment index and most vascular parameters, as well as lower high-density lipoprotein (HDL)-cholesterol than overweight children. Moreover, overweight children showed higher BP, insulin and uric acid, and lower HDL-cholesterol than normal weight children. The CDC criteria yielded similar results, although with fewer differences between obese and overweight children. Applying Spanish criteria, the differences between obese and overweight children disappeared.

CONCLUSIONS: WHO and CDC BMI-for-age references and cut-offs are useful for defining obesity and being overweight in children because they clearly identify metabolic and vascular comorbidities. The Spanish Reference Criteria underdiagnose obesity because overweight children show comorbidities typical of the obese.