The results of bivariate correlation analyses showed that there was a positive correlation between elevated RDW and age (r = 0.188, P <  0.001), HTN (r = 0.080, P <  0.001), DM (r = 0.052, P <  0.001), BUN(r = 0.039, P <  0.001), CPB time (r = 0.159, P <  0.001), ACC time (r = 0.136, P <  0.001), AKI stage (r = 0.171, P <  0.001) and a negative correlation with male (r = − 0.096, P <  0.001), BMI(r = − 0.045, P = 0.01), hemoglobin (r = − 0.147, P <  0.001), Albumin (r = − 0.047, P <  0.001), and eGFR (r = − 0.105, P <  0.001) (see Table 4). This evidence concerns the gene ALB and hypertensive disorder.