Analysis of the Agreement Between the World Health Organization Criteria and the National Cholesterol Education Program-III Definition of the Metabolic Syndrome: Results from a population-based survey

Our objective was to evaluate the diagnostic proficiency of the World Health Organization (WHO) and the National Cholesterol Education Program (NCEP)-III definitions (1,2) for the metabolic syndrome in a Mexican nationwide, population-based survey. Details of the sampling procedures have been previously described (3). The population was composed of 2,158 men and women aged 20–69 years sampled after a 9- to 12-h fasting period. For the WHO criteria, insulin resistance was diagnosed if a nondiabetic case had fasting insulin concentrations ≥126 pmol/l (21 μU/ml) (>75th percentile in Mexican adults). The age-adjusted prevalence was 13.61% for the WHO criteria (n = 268) and 26.6% for the NCEP-III definition (n = 574). After excluding patients with diabetes, the prevalence was 9.2 and 21.4%, respectively. The agreement between the definitions was assessed in 1,969 subjects; 189 cases were eliminated due to the lack of a urine sample.

The number of abnormal cases was lower using the WHO criteria. Only 237 of the 545 subjects (43.4%) who fulfilled the NCEP criteria were diagnosed as affected using the WHO definition. Just 16 of 253 cases (6.3%) detected by the WHO definition did not fulfill the NCEP definition. The agreement between the criteria was moderate (κ = 0.507). On the other hand, the subjects diagnosed using the WHO recommendations had a worse profile than the cases detected by the NCEP-III definition only—they had a higher BMI and higher non-HDL cholesterol, triglyceride, and glucose concentrations. The demonstration of insulin resistance among the nondiabetic population caused the lack of agreement in 202 of the 242 cases that fulfilled the NCEP definition but failed the WHO criteria. Other reasons for disparity were the higher thresholds used by the WHO criteria; these differences explained the lack of agreement in 66 of the 152 cases with diabetes.

In conclusion, the prevalence of the metabolic syndrome is influenced by the selection of the diagnostic criteria. The WHO criteria identified a lower number of cases than the NCEP-III definition. These differences were explained mainly by the inclusion of abnormally high insulin concentrations as a diagnostic criterion. However, the presence of insulin resistance may help to identify patients more severely affected (4).