Metabolic Syndrome: prevalence and prediction of mortality in elderly individuals

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.

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).

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.

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.