Background: To describe the frequency, in some European populations, of the World Health Organisation (WHO) defined metabolic syndrome and to compare the frequency of this syndrome with an alternative definition for non-diabetic subjects, called the insulin resistance syndrome proposed by the European Group for the Study of Insulin Resistance (EGIR).
Methods: Investigators of eight European studies contributed, according to a written protocol, the frequencies of abnormalities of these two syndromes, by sex and age class, as well as the overall frequencies of the syndromes and the average number of abnormalities: 8200 men and 9363 women were included.
Results: The frequency of both syndromes increased with age and was almost always higher in men than women for a given age. In non-diabetic subjects the frequency of the WHO syndrome varied between 7% and 36% for men 40 to 55 years; for women of the same age, between 5% and 22%. The EGIR syndrome was less frequent than the WHO syndrome (1% to 22% in men, 1% to 14% in women 40-55 years), and in men this was mainly due to the differing definitions of central obesity, as the WHO definition included overall obesity, BMI > or = 30 kg/m(2).
Conclusions: There is great variability in the frequency of the syndrome between different populations, due to the differing frequencies of the abnormalities and no doubt to the differing methodologies of measurement. Prospective studies and advances in the knowledge of physio-pathological mechanisms are required to determine the most appropriate and practical definition of the syndrome.