Definitions
Nephrotoxicity was evaluated according to the RIFLE (Risk, Injury, Failure, Loss, End-stage kidney disease) criteria based on serum creatinine concentrations. According to this system, risk (R) is defined as a 1.5-fold increase in serum creatinine concentration, injury (I) as a 2-fold increase in serum creatinine concentration, and failure (F) as a 3-fold increase in serum creatinine or concentration ≥4 mg/dL; loss (L) is defined as persistent acute renal failure >4 weeks and end-stage renal disease (E) is defined as persistent failure >3 months (10). Infection was diagnosed according to the criteria defined by the Centers for Disease Control and Prevention (11). Urea and creatinine concentrations on the first day of COL therapy were accepted as initial values. In patients with nephrotoxicity, the dose of COL was adjusted according to creatinine clearance. Urea and creatinine concentrations on the day of discontinuation of COL treatment were evaluated as end-of-treatment values.