Red Cell Distribution Width is independently associated with Mortality in Sepsis

Background: Mortality in sepsis remains high. Studies in small cohorts have shown that red cell distribution width (RDW) is associated with mortality. The aim of this study was to validate these findings in a large multi-centre cohort. Methods: We conducted this retrospective analysis of the multi-center eICU Collaborative Research Database in 16,423 septic patients. We split the cohort in patients with low (≤15%; n=7,129) and high (>15%; n=9,294) RDW. Univariable and multivariable multilevel logistic regression were used to fit regression models for the binary primary outcome of hospital mortality and the secondary outcome ICU mortality with hospital unit as random effect. Optimal cut-offs were calculated using the Youden-index. Results: Patients with high RDW were more often older than 65 years (57% vs. 50%; p<0.001) and had higher APACHE IV scores (69 vs. 60 pts.; p<0.001). Both hospital- (aOR 1.18 95%CI 1.16-1.20; p<0.001) and ICU-mortality (aOR 1.16 95%CI 1.14-1.18; p<0.001) were associated with RDW as a continuous variable. Patients with high RDW had a higher hospital mortality (20 vs. 9%; aOR 2.63 95%CI 2.38-2.90; p<0.001). This finding persisted after multivariable adjustment (aOR 2.14 95%CI 1.93-2.37; p<0.001) in a multilevel logistic regression analysis. The optimal RDW-cut-off for prediction of hospital mortality was 16%. Conclusion: We found an association of RDW with mortality in septic patients and propose an optimal cut-off value for risk stratification. In a combined model with lactate, RDW shows equivalent diagnostic performance to SOFA score and APACHE IV.