Metabolic syndrome, inflammation, and incident heart failure in the elderly: the cardiovascular health study

Abstract

Background: Inflammation markers and metabolic syndrome (MetS) are associated with risk of congestive heart failure (CHF). We evaluated whether combining inflammation markers and MetS provided additive information for incident CHF and if incorporating inflammation markers to the MetS definition added prognostic information.

Methods and results: We studied 4017 men and women > or =65 years old, without baseline CHF or diabetes, participating in the Cardiovascular Health Study, an observational study with 12.2 years follow-up and 966 cases of incident CHF. Baseline "C-reactive protein (CRP)-MetS" or "interleukin (IL)-6-MetS" were defined as presence of 3 out of 6 components, with elevated CRP (> or =3 mg/L) or IL-6 (> or =2.21 pg/mL) as a sixth component added to ATPIII criteria. Cox models adjusted for CHF risk factors and incident coronary disease were used to calculate hazard ratios for CHF. MetS and elevated inflammation markers were independently associated with CHF risk (hazard ratios, 95% CI: 1.32, 1.16 to 1.51 for MetS; 1.53, 1.34 to 1.75 for CRP; 1.37, 1.19 to 1.55 for IL-6). There was a 20% relative excess risk attributed to the combination of MetS and CRP (95% CI, -44% to 88%). CRP-MetS and IL-6-MetS definitions reclassified 18% and 13%, respectively of participants as MetS. Both CRP-MetS and IL-6-MetS increased risk of CHF by 60% compared with those without MetS.

Conclusions: MetS and inflammation markers provided additive information on CHF risk in this elderly cohort. Inflammation-incorporated MetS definitions identified more participants with the same risk level as ATPIII MetS. Considering inflammation markers and MetS together may be useful in clinical and research settings.

Figure 1

Time free from Congestive Heart Failure based on MetS and inflammation status (1A: CRP, 1B: IL-6). Solid black line indicates subjects with MetS and an elevated inflammation marker (1A: CRP, 1B: IL-6). Solid gray line indicates subjects without MetS but with an elevated inflammation marker. Dashed line indicates subjects with MetS but without an inflammation marker. Dotted line indicates subjects with neither of them. MetS indicates metabolic syndrome; CRP, C-reactive protein; IL-6, interleukin-6.