JMIR Publications

ABSTRACT

Background:

The metabolic syndrome (MetS) is a common metabolic disorder that results from the increasing prevalence of obesity, which has been an increasing concern in recent years. Previous evidence indicated that MetS was associated with mortality; however, different definitions of MetS were used. In 2005, ATP III updated again the definition of MetS according to the modified American Diabetes Association (ADA) criteria for impaired fasting glucose, which has been widely adopted in the United States and elsewhere due to its simplicitye to use in a clinical setting and its advantage of avoiding emphasis on a single cause. Therefore, it is necessary to conduct a novel study among other populations and countries with larger sample size using an updated definition of MetS and death code to examine the association of MetS with all-cause and cause-specific mortality.

Objective:

We aimed to examine the associations of metabolic syndrome (MetS) with all-cause and cause-specific mortality.

Methods:

A total of 36,414 adults were included in the present study from the US Third National Health and Nutrition Examination Survey (NHANES III) and NHANES 1999-2014. Death outcomes were ascertained by linkage to National Death Index records through 31 December 2015. MetS was defined by the NCEP ATP III-2005 criterion. Complex survey design factors including sample weights, clustering, and stratification were considered for all analyses with instructions for using NHANES data. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality from all causes, heart disease, diabetes and cancer.

Results:

We observed 8,494 deaths during 16.71 years of follow-up. Compared with those without MetS, individuals with MetS were associated with a significantly elevated multi-adjusted HR of 1.24 (95%CI, 1.16-1.33), 1.44 (95%CI, 1.25-1.66) and 5.15 (95%CI, 3.15-8.43) for all cause, heart diseases and diabetes mellitus (DM), respectively, while no significant association was found for cancer mortality (HR=1.17; 95%CI, 0.95-1.43). Similar findings were observed between different number of MetS components and all-cause, heart disease and DM mortality. Moreover, the risk of mortality increased with the increase of number of MetS components, and the associations between different MetS components and mortality varied. In the stratified analyses, significant associations between MetS and all-cause mortality were found among most groups, similar findings were observed in the associations of MetS with heart disease and DM mortality.

Conclusions:

Our study provides additional evidence that MetS and its components are significantly associated with all-cause, heart disease and diabetes mortality, but not with cancer mortality. MetS and its individual component should be paid more attention by health care professionals.