Allogeneic hematopoietic stem cell transplantation for patients with mildly reduced renal function as defined based on creatinine clearance before transplantation

While renal comorbidity is generally defined by the serum creatinine level, the creatinine clearance rate (Ccr) is a more accurate indicator of renal function. Therefore, we retrospectively assessed how mildly reduced renal function as defined based on Ccr affects the outcome after allogeneic hematopoietic stem cell transplantation (HSCT). Patients who underwent allogeneic HSCT at the eight institutes of the Kanto Study Group for Cell Therapy were included in this study. Based on the corrected Ccr, patients were classified into group 0 (n = 440, ≥ 90 mL/min/1.73 m²), group 1 (n = 56, 60-89 mL/min/1.73 m²), or group 2 (n = 11, 30-59 mL/min/1.73 m²). Therefore, 67 patients were considered to have mild renal impairment, whereas only 2 had a serum creatinine level higher than 1.2 mg/dL. Twenty-eight patients required hemodialysis after HSCT, with 5.5, 5.4, and 9.1 % in groups 0, 1, and 2, respectively (p = 0.65). The incidence of non-relapse mortality (NRM) was higher in group 2, although these differences were not statistically significant probably due to the small sample size (23.7, 28.2, and 47.2 % at 3 years, p = 0.20). In conclusion, NRM may be associated with mildly reduced renal function before allogeneic HSCT, which cannot be detected by measurement of the serum creatinine level alone.