Metabolic syndrome and coronary heart disease risk in a population-based study of middle-aged men from France and Northern Ireland. A nested case-control study from the PRIME cohort.

Metabolic Syndrome (MetS) was found associated with an increased CHD risk in several studies but data about this relationship in Southern Europe are lacking. We studied the association of MetS according to three different indexes (the National Cholesterol Education Program's definition (NCEP), a modified World Health Organization's definition (WHO) and the recent International Diabetes Federation's definition (IDF)) with CHD risk in a case-control study nested within the PRIME cohort, composed of subjects from France (Southern Europe) and Belfast (Northern Europe). The PRIME prospective study is composed of 10 592 men, aged 50-59 at baseline and followed for 5 years. Subjects included in this nested case-control study were 296 cases of incident CHD and 540 controls, who remained free of CHD during the 5 years of follow-up of the PRIME cohort and matched for age, recruitment centre and recruitment date. All subjects had questionnaires and a medical examination at baseline, and a blood sample was taken. Using the IDF's, the WHO's and the NCEP's definitions respectively, the frequency of MetS was 38.9%, 35.5% and 29.7% in cases and 32.4%, 28.7% and 22.6% in controls. After adjustment for physical activity, smoking and drinking habits, MetS was associated with CHD risk whichever the definition used (ORIDF=1.41 [1.02-1.95], P<0.04, ORWHO=1.40 [1.01-1.94], P<0.05 and ORNCEP=1.46[1.04-2.04], P<0.04). These results were homogeneous in France (low risk of CHD) and Belfast (high risk of CHD). Our results add further evidence that MetS is predictive of CHD risk in middle-aged men from Northern and Southern Europe, and highlight differences between the three definitions studied.