Associations of Metabolic Syndrome and its Components with Mortality in the Elderly: A Cohort Study of 73,547 Taiwanese Adults

Available evidence shows that metabolic syndrome (Mets) has clear adverse effects for middle-aged and pre-elderly adults; however, the effect of Mets on mortality among elderly adults remains unclear. In addition, the comparative utility of Mets and its component for predicting mortality among the elderly has not been clearly established. Using data from a large Taiwanese cohort, we evaluated the effect of Mets and its components on subsequent all-cause and cause-specific mortality overtime among the elderly. A total of 73,547 elders (age ≥65 years) participated in the Taipei Elderly Health Examination Program from 2007 to 2010. Mets was diagnosed using the adult treatment panel III criteria, and mortality was ascertained by using national death records. Time-dependent analysis was used to evaluate associations of Mets and its components with all-cause mortality, cardiovascular disease (CVD) mortality, and expanded CVD mortality. This retrospective cohort study found that 42.6% of elders had Mets. During 194,057 person-years of follow-up, 2944 deaths were observed. After adjusting for sociodemographic characteristics and comorbidities, Mets was associated with increased risk of expanded CVD mortality (hazard ratio [HR], 1.27; 95% CI, 1.10-1.46) but not all-cause or CVD mortality. Among Mets components, decreased high-density lipoprotein cholesterol (HDL-C, HR 1.25, 95% CI 1.13-1.37) and hyperglycemia (HR 1.21, 95% CI 1.12-1.31) were associated with a significant increase in all-cause mortality. Hypertension and low HDL-C were predictors of CVD mortality and expanded CVD mortality, and, as compared with Mets, were associated with a higher risk of expanded CVD mortality. The present findings indicate that, in elderly adults, individual components of Mets are better predictors of all-cause and cause-specific mortality than is Mets as a whole. Our results suggest that future efforts should focus on preventing and managing individual risk factors (particularly hypertension, low HDL-C, and hyperglycemia) rather than on "diagnosing" Mets in elders.