Abstract: Objectives To evaluate the value of red blood cell distribution width (RDW) for the prediction of mortality in patients on continuous renal replacement therapy (CRRT) due to acute kidney injury (AKI) following cardiac surgery. Methods Patients without any history of chronic kidney diseases but with AKI following cardiac surgery and underwent continuous veno-venous hemodiafilitration (CVVHDF) in our medical center from January 2012 to June 2013 were enrolled in this study. They were assigned into either survival group or death group. Data from pre-surgery and pre-CVVHDF were collected and analyzed. The value of RDW for mortality prediction was assessed by receiver operator curve, and the 28- day survival rate between high-level and low-level RDW groups was further compared. Results Seventeen adult patients with AKI following cardiac surgery and underwent CVVHDF were enrolled in this study. Six patients survived and 11 patients died, with the mortality of 64.7%. The death group showed a higher level of RDW and SOFA score than those in the survival group (P=0.048 and 0.014, respectively). The area under receiver operator curve (AUC) for mortality prediction was 0.765 for RDW and 0.848 for SOFA score (P=0.024 and 0.0002, respectively), and there was no statistical significance between RDW and SOFA scores (P=0.541). Patients with a RDW level >15% exhibited significantly higher 28-day mortality rate than those with lower RDW level (P= 0.038). Conclusions The present study demonstrated that RDW may be an additive predictor for mortality in patients on CRRT due to AKI following cardiac surgery.

Key words: Red blood cell distribution width, Cardiac surgery, Acute kidney injury, Continuous renal replacement therapy