Whereas the global epidemic of type 2 diabetes is now well characterized (1), data on the occurrence of the metabolic syndrome in populations are limited (2–5). The lack of an accepted internationally agreed definition has impeded epidemiological work on the prevalence and antecedents of this syndrome. Two definitions of the syndrome have been proposed, one by the World Health Organization (MSWHO) (6), and one in the U.S. Third Report of the National Cholesterol Education Program, Adult Treatment Panel, 2001 (ATP III) (4).
We have estimated and compared the prevalence of the metabolic syndrome according to both criteria in a cross-sectional study involving a group of 1,018 subjects aged 50–69 years of Irish ethnic origin. Participants were recruited from a primary care setting using stratified random sampling with a response rate of 69.9%. Details of the sample recruitment, the study questionnaire, anthropometric and physical measurements, and measurements of glucose and lipids have been described (7). Data on all variables required to define the metabolic syndrome according to both criteria were available for 890 participants.
The prevalence of the metabolic syndrome according to the WHO definition was 21.0% (95% CI 18.7–24.1%) and 20.7% (19.1–24.4%) according to the ATP III definition. A total of 13.1% (10.9–15.3) met the criteria for both syndromes and 28.5% (25.6–31.4) for one or both. The prevalence of the WHO definition of metabolic syndrome was higher in men (24.6%) than in women (17.8%), whereas prevalence of metabolic syndrome defined by ATP III was similar in men and women (21.8 vs. 21.5%). The prevalence of the syndrome increased with age: WHO: 15.2% in those aged 50–59 years to 24.3% in those aged 60–69 years; ATP III: 16.4% in those aged 50–59 years to 24.3% in those aged 60–69 years. The level of agreement between the two definitions of the syndrome was only moderate (κ statistic = 0.53, 0.46–0.60).
In summary, approximately a quarter of middle-aged men and women met one or both of the current criteria for the metabolic syndrome. However, there is only moderate agreement between the two definitions of the syndrome. There is an urgent need for a single internationally agreed definition of the metabolic syndrome.
