The metabolic syndrome is not a sensible tool for predicting the risk of coronary heart disease

Abstract

The metabolic syndrome (MS) is a popularly used risk marker for coronary heart disease (CHD), yet its utility is in doubt. Cohort study based in Glasgow, Scotland, of 1471 men and women free of cardiovascular disease, followed up for a median of 13.7 years. MS was defined according to current criteria, requiring at least three of five dichotomous risk factors to be positive. Cox models were used to obtain hazard ratios (HRs) and discrimination was quantified by areas under receiver operating characteristic curves (AUCs) using 500 bootstrap samples. The HR (95% confidence interval) for CHD, MS versus no MS was 2.23 (1.67-2.97). However, the HR rose monotonically when plotted against the number of positive components, with no suggestion of a threshold effect at three positive components. Furthermore, the HR also changed monotonically as each of the five continuous variables defining the different components increased, again with no obvious threshold effects. The AUC for MS was low, at 0.5764, this being significantly (P<0.0001) lower than the AUCs for other risk prediction models, including the Framingham score, 0.7517. Although MS is related to CHD, there is no epidemiological justification for using it, rather than other criteria, as a risk predictor for CHD.