Metabolic Syndrome, C-Reactive Protein, and Mortality in U.S. Blacks and Whites: The Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Abstract

OBJECTIVE We evaluate associations of metabolic syndrome (MetS), C-reactive protein (CRP), and a CRP-incorporated definition of MetS (CRPMetS) with risk of all-cause mortality in a biracial population. RESEARCH DESIGN AND METHODS We studied 23,998 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, an observational study of black and white adults ≥45 years old across the U.S. Elevated CRP was defined as ≥3 mg/L and MetS by the revised Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III; ATP III) criteria (three of five components). CRPMetS was defined as presence of three out of six components, with elevated CRP added to ATP III criteria as a sixth component. Cox models were used to calculate hazard ratios (HRs) for all-cause mortality, and population attributable risk (PAR) was calculated. Stratified analyses based on race and diabetes status were performed. RESULTS There were 9,741 participants (41%) with MetS and 12,179 (51%) with CRPMetS at baseline. Over 4.8 years of follow-up, 2,050 participants died. After adjustment for multiple confounders, MetS, elevated CRP, and CRPMetS were each significantly associated with increased mortality risk (HRs 1.26 [95% CI 1.15–1.38], 1.55 [1.41–1.70], and 1.34 [1.22–1.48], respectively). The PAR was 9.5% for MetS, 18.1% for CRP, and 14.7% for CRPMetS. Associations of elevated CRP and of CRPMetS with mortality were significantly greater in whites than blacks, while no differences in associations were observed based on diabetes status. CONCLUSIONS By definition, CRPMetS identifies more people at risk than MetS but still maintains a similar mortality risk. Incorporating CRP into the definition for MetS may be useful in identifying additional high-risk populations to target for prevention.