Prevalence of metabolic syndrome in a Portuguese obese adolescent population according to three different definitions

In order to determine the prevalence of metabolic syndrome (MS) in a Portuguese pediatric overweight population according to three different sets of criteria, 237 overweight and obese adolescents were evaluated at engagement in a specific multidisciplinary program. Two of the used definitions were based on the National Cholesterol Education Program (ATPIII) guidelines modified for pediatric age and were proposed by Cook et al. (Arch Pediatr Adolesc Med 157(8):821-827, 2003) and de Ferranti et al. (Circulation 110(16):2494-2497, 2004). The third definition used resulted from a consensus of the International Diabetes Federation (IDF 2005). All of them include five components: waist circumference, blood pressure, high-density lipoprotein cholesterol, triglycerides, and fasting glucose values, with different cut-off points. Of the studied sample, 53% were girls, median age 13.4 years, 89% classified as obese, and the remaining as overweight. MS prevalence was 15.6%, 34.9%, and 8.9% according to Cook's, de Ferranti's, and IDF definitions, respectively. No adolescent fulfilled the five MS criteria, and only three (1.2%), 15 (6%), and 13 (5.1%) had no criteria at all, according to the three definitions used. Waist circumference was the most prevalent component (89.5%, 98.7%, and 93.2%), and high fasting glucose the least (1.3% for the two first and 2.5% according to the IDF definition). A significant correlation between increased body mass index and MS was found, using the two first definitions (Cook et al. p < 0.05; de Ferranti et al. p < 0.01), but not when using the third one. Considerable prevalence differences were found using three different MS criteria. It is urgent to establish a consensus on MS definition to allow early identification of adolescents at risk and the development of prospective studies to define what cut-offs are the best indicators of future morbidity.