Background: Different definitions of the metabolic syndrome are used, and at least one of these does not include indices of glucose intolerance and/or insulin resistance as obligatory components. In this paper, we examine the predictive power of indices having and not having these obligatory components.
Methods: A total of 1135 men and women, aged 37-61 years, were randomly selected from the populations of Mölndal and Orebro, Sweden. Mortality rate and incidence of cardiovascular morbidity were analyzed in subjects with and without the metabolic syndrome according to the definitions of WHO (World Health Organization), EGIR (European Group for the study of Insulin Resistance), and ATPIII (Adult Treatment Panel-III Guidelines). Atherosclerotic morbidity was traced until December 2002 and mortality until December 2003. Due to lack of data, our WHO definition does not include information on micro-albuminuria.
Results: There were 17 deaths during the 3-8 year follow-up. As compared to subjects without the metabolic syndrome, all-cause mortality was increased significantly in subjects with the syndrome defined according to WHO(non u-alb) (hazards ratio [HR] 2.98, 95% CI 1.07, 8.28, p = 0.036) but not according to EGIR (HR 1.93, 95% CI 0.67, 5.55, p = 0.230) or ATPIII (HR 0.88, 95% CI 0.20, 3.89, p = 0.870). Incident cases of ischemic heart, cerebrovascular, and/or peripheral arterial disease (n = 18) were related to the metabolic syndrome according to WHO(non u-alb) and EGIR but not according to ATPIII.
Conclusions: Inclusion of glucose intolerance and/or insulin resistance as obligatory criteria in the definition of the metabolic syndrome seems to be important for the ability to predict all-cause mortality and incident cardiovascular morbidity.