Prevalence of metabolic syndrome (MS) in children and adolescents with varying degrees of obesity

Objective Childhood obesity is increasingly common and is associated with health problems; in particular, obesity plays a central role in the metabolic syndrome (MS). We estimated the prevalence of MS in Caucasian children and adolescents with varying degrees of obesity. Patients and methods We studied 191 obese [body mass index (BMI) > 97th percentile] children and adolescents. Obesity was stratified on the basis of a threshold BMI z-score and subjects were classified as moderately (z-score 2-2.5) or severely obese (z-score > 2.5). Seventy-six, nonobese subjects were recruited into a comparison group. Thirty-one of them were of normal weight (BMI < 75th percentile) and 45 overweight (BMI 75th-97th percentile). Patients were classified as having MS if they met three or more of the following criteria for age and sex: BMI > 97th percentile, triglyceride levels > 95th percentile, high density lipoprotein (HDL) cholesterol level < 5th percentile, systolic or diastolic blood pressure > 95th percentile and impaired glucose tolerance (blood glucose level: 7.8-11.1 mmol/l at 2 h). Insulin resistance was calculated using the homeostasis model assessment for insulin resistance (HOMA-IR) and impaired insulin sensitivity was defined as a HOMA-IR >= 2.5 in prepubertal patients and HOMA-IR > 4 in pubertal subjects. Results The overall prevalence of MS was 13.9% and was present in 12.0% of moderately obese and 31.1% of severely obese subjects; no overweight or normal weight subjects met the criteria for MS. The rate of the MS increased progressively with increasing BMI categories (P < 0.001). Severely obese patients had a threefold increased risk with respect to moderately obese patients. Conclusions The prevalence of the MS is higher in obese as opposed to nonobese subjects and increases with severity of obesity.