Risk Stratification Based on Metabolic Syndrome as well as Non- Metabolic Risk Factors in the Assessment of Carotid Atherosclerosis

AIM: We aimed to develop a new approach to risk stratification using metabolic syndrome as well as traditional non-metabolic risk factors, and to examine its validity in carotid atherosclerosis. METHODS: A total of 1,189 men and women aged 21-93 years old were stratified according to the absence or presence of metabolic syndrome defined by Japanese criteria, non-metabolic risk factors, and a past history of coronary heart disease. The risk stratification was as follows: (S-1) persons without a past history, non-metabolic risk factors and metabolic syndrome, (S-2a) those with metabolic syndrome only, (S-2b) those with non-metabolic risk factors only, (S-3) those with non-metabolic risk factors and metabolic syndrome but no past history, and (S-4) those with a past history. Carotid atherosclerosis was defined as maximum intima-media thickness ≥1.1 mm of the far wall of the common carotid artery. RESULTS: Compared with individuals without these three risk components (S-1), the odds ratio was 7.2 (2.8-18.6) for a past history (S-4), 4.3 (1.7-10.9) for non-metabolic risk factors plus metabolic syndrome but no past history (S-3), 2.6 (1.1-6.4) for non-metabolic risk factors only (S-2b) and 0.5 (0.0-5.7) for metabolic syndrome only (S-2a). Net reclassification improvement from metabolic syndrome only (presence versus absence) to our risk stratification (≥S-3 versus < S-3) was 16.4% (p< 0.0001), suggesting that our risk stratification improved the classification of atherosclerosis in comparison to metabolic syndrome only. CONCLUSION: Risk stratification based on traditional non-metabolic risk factors plus metabolic syndrome rather than metabolic syndrome only appears to be more useful for the clinical assessment of atherosclerosis, and probably in the prevention and control of atherosclerotic disease.