Background: To evaluate in the general population the prevalence of undiagnosed metabolic syndrome (MS), defined according to the National Cholesterol Education Program (NCEP) and International Diabetes Federation (IDF) criteria.
Methods: A population-based cross-sectional study of 1175 asymptomatic adults in North-Western Italy.
Results: The prevalence of undiagnosed MS was 16.4% (95% CI=14.4-18.6) (NCEP) and 28.0% (25.4-30.6) (IDF), respectively, 5.2% (3.6-7.3) and 8.9% (6.6-11.3) in normal-BMI and 26.6% (23.3-30.2) and 45.3% (41.3-49.2) in overweight/obese individuals. Of the total cohort, 52% were overweight/obese and they accounted for 85% of the cases of MS; a further 19% were normal weight with light physical activity and accounted, respectively, for 12% (NCEP) and 13% (IDF) of the cases. Only 25% (NCEP) and 14% (IDF) of participants showed no component of the MS (respectively, 40 and 26% of those not-overweight and 11 and 3% of those overweight/obese).
Conclusions: More than 97% of unknown MS cases would be identified among apparently healthy individuals when overweight/obese, and normal-BMI subjects with low physical activity were screened. These two criteria might, therefore, be used to prioritise screening programmes in asymptomatic subjects, since even apparently healthy individuals, who are not-overweight, frequently show one or more metabolic abnormalities, whose co-existence has been demonstrated to be hazardous.