Metabolic syndrome, its components and mortality: A population-based study

Background: The association between Metabolic syndrome (MetS), its components and mortality has not been clearly established. The aim of this study was to determine the effects of Mets and its components on all cause and cause-specific mortality and to examine whether MetS or its components were better predictors of mortality. Methods: In this retrospective cohort study, we used data from the Zanjan Healthy Heart Study performed in 2003 on 4000 persons. Based on the definitions provided by the NCEP- ATPIII, 1051 participants with MetS and 1219 with none or one of its components at study entry were enrolled. Information regarding the mortality and morbidity of 502 participants with MetS and 523 controls was collected in 2013 by telephone. Cause of death was defined as Cardio-Vascular Disease (CVD) or non-CVD. Data were analyzed using the Cox Proportional Hazards model to estimate the hazard ratios predicted by MetS and its individual components. Results: The median duration of follow-up was 104±10.7 months. Thirty-five deaths occurred, including 18 cardiovascular deaths. The proportion of those with CVD, hypertension, diabetes or hospital stay was statistically higher in MetS patients than controls (p<0.0001). The hazard ratios of all-cause and cardiovascular mortality for those with MetS were 1.75 (%95CI: 0.88-3.47) and 3.66 (%95CI: 1.2-11.1) higher than controls, respectively. Among the components of MetS, only hypertension predicted a higher risk of all-cause and CVD mortality after adjusting for age and sex. Conclusion: The results of this study indicated that MetS was associated with a higher risk of CVD mortality, morbidity, and hospital stay. Among the components of MetS, the association of hypertension was stronger compared to MetS as a whole. Therefore, this study confirms that MetS is a risk factor for CVD mortality, but not beyond the risk associated with its individual components.