EPO and acute kidney injury: Based on these results, the following variables were entered into the multivariate logistic regression model as dependent variables: the continuous variables of admission APACHE II score, mean daily SOFA score and phlebotomy volumes (both after day 21), and ICU LOS; and the binary variables of sex, surgical admission, coronary artery disease, erythropoietin therapy, iron therapy, day 21 hemoglobin, inotrope/vasopressor therapy, and acute renal failure requiring dialysis.