Interaction between inflammation and blood viscosity predicts cardiovascular mortality.

Abstract

Objectives: Inflammation and increased blood viscosity are associated with increased risk of cardiovascular mortality. Erythrocyte sedimentation rate (ESR) and hematocrit both influence blood viscosity whereas the first also is a marker of inflammation. We aimed to investigate ESR, hematocrit and the interaction between them as predictors of cardiovascular mortality during 26 years follow-up among healthy middle aged men.

Design: Four hundred and eighty eight men aged 40-59 were extensively examined in 1972-1975 and followed over a period of 26 years. Risk estimation was made in Cox proportional hazards and adjusted for age, smoking, systolic blood pressure, total serum cholesterol, and physical fitness.

Results: A 2.44-fold (95% CI 1.37-4.35) adjusted risk of cardiovascular mortality was found in the highest quartile of hematocrit compared to the lowest. Among the 265 men who had an ESR <6 mm/h (median), the adjusted risk of cardiovascular mortality was 3.05-fold (95% CI 1.49-6.23) in the highest quartile of hematocrit compared to the lowest. This association was not observed among the 223 men with ESR <6 mm/h.

Conclusion: Elevated hematocrit is independently associated with increased long-term risk of cardiovascular mortality in men with high ESR. Our data suggest that the combination of inflammation and blood viscosity may improve the prediction of cardiovascular risk.