Impact of reference category and number of traits in the cluster on risk of coronary heart disease in metabolic syndrome: prospective data from the Bruneck study.

BACKGROUND

We assessed the risk of coronary heart disease (CHD) in subjects with metabolic syndrome using different reference categories and focusing on the number of traits in the cluster.

METHODS

For 15 years, we followed 840 subjects from the general population living in Bruneck, northeastern Italy, aged 40-79 years, without CHD at baseline. Metabolic syndrome was diagnosed at baseline using American Heart Association/National Heart, Lung, and Blood Institute criteria. Subjects with the syndrome were compared to subjects without, as well as to subjects without any metabolic abnormality, using Cox models adjusted for sex, age, smoking, and low-density lipoprotein-cholesterol. There were 89 incident CHD cases.

RESULTS

In subjects with the metabolic syndrome, the risk of CHD was1.5-fold higher when subjects without the syndrome were the reference category. CHD risk, however, was 12.5-fold higher (95% confidence interval [CI], 1.7-92.7, P=0.014) when subjects without any metabolic abnormality composed the reference category. As compared to subjects with no abnormalities (who had a trivial number of CHD events), the risk increased from subjects with one (hazard ratio 7.6, 95% CI 1.0-56.5, P=0.047) to those with 2, 3, and 4/5 abnormalities (11.6, 1.6-84.9, P=0.016; 12.9, 1.7-96.0, P=0.013; and 10.1, 1.3-79.2, P=0.028), respectively.

CONCLUSIONS

When compared to the reference category of people without any metabolic abnormality, those with the metabolic syndrome had high cardiovascular risk. However, in the Bruneck population, the risk of CHD seems to be similar in subjects having two or three to five clinical features of metabolic syndrome. Therefore, the clinical utility of identifying subjects with the syndrome using current diagnostic criteria remains uncertain and might be the focus of further specific studies.