Plasma fibrinogen associates independently with total and cardiovascular mortality among subjects with normal and reduced kidney function in the general population

Background: The contribution of novel risk factors to mortality in chronic kidney disease remains controversial. Aim: To explore the association of plasma fibrinogen with mortality among individuals with normal and reduced kidney function. Methods: We identified 9184 subjects, age 40 and over from the Third National Health and Nutrition Examination Survey (1988-94) with vital status assessed through 2006. Plasma fibrinogen was modeled as continuous variable and in quartile groups (0 to <7.7, 7.7 to <9.0, 9.0 to <10.5 and ≥10.5 μmol/l) with total and cardiovascular mortality across categories of glomerular filtration rate (eGFR); <60, 60-90, >90 ml/min/1.73 m² using Cox regression. Results: In multivariate analysis, the adjusted hazard ratio (HR) per 1 μmol/l (34 mg/dl) increase in fibrinogen was 1.07 [95% confidence interval (CI) 1.04-1.09] for total mortality and 1.06 (95% CI 1.03-1.09) for cardiovascular mortality. The adjusted HR for total mortality was 1.05 (1.01-1.09) for subjects with eGFR 60-90 ml/min/1.73 m² and 1.06 (1.02-1.10) for subjects with eGFR <60 ml/min/1.73 m². Subjects in the highest quartiles within each eGFR category; >90, 60-90 and <60 ml/min/1.73 m² experienced HRs of 1.45 (95% CI 1.03-2.03), 1.35 (95% CI 1.00-1.83) and 1.72 (95% CI 1.14-2.58), respectively, compared with subjects in the lowest quartile group. The patterns were similar for cardiovascular mortality. Conclusions: Plasma fibrinogen associates with mortality among subjects with mild to moderate kidney impairment as it does in subjects with normal kidney function and should be considered a therapeutic target for cardiovascular risk reduction.