Metabolic Syndrome: prevalence and prediction of mortality in elderly individuals

Abstract

Objective: Little is known about the prevalence of the metabolic syndrome among elderly people in Italy, its association with all-cause mortality, and whether measurement of serum C-reactive protein (CRP) and interleukin (IL)-6 affects this association.

Research design and methods: The baseline prevalence of metabolic syndrome, diagnosed according to the National Cholesterol Education Program (NCEP) criteria, and all-cause mortality at 4 years were recorded in an Italian population-based cohort (981 subjects, 55% women, aged 65-97 years). A Cox model adjusted for sociodemographic, lifestyle, and medical variables was used to investigate 1) whether metabolic syndrome was a predictor of mortality and 2) how the association was affected by baseline high CRP (>3 mg/l) and IL-6 (>1.33 pg/ml).

Results: Overall, metabolic syndrome prevalence was 27.2% [95% CI 24.0-30.5] and higher in women (33.3% [28.7-38.0]) than in men (19.6% [15.5-24.2]). During follow-up, 137 deaths occurred. Using the no metabolic syndrome/no high IL-6 group as the reference, mortality was not associated with the metabolic syndrome alone (multivariable-adjusted hazard ratio 1.24 [0.60-2.59]), only weakly associated with high IL-6 alone (1.66 [1.04-2.63]), but strongly associated with the concurrent presence of metabolic syndrome and high IL-6 (3.26 [2.00-5.33]). High CRP was not a mortality predictor (0.83 [0.58-1.20]) nor did it affect the association of the other variables with mortality.

Conclusions: Metabolic syndrome by NCEP criteria is highly prevalent in the Italian elderly population. It is not itself associated with mortality but may improve the usefulness of IL-6 as a mortality predictor in older age.