Acute Kidney Injury (AKI) in Pediatric Hematopoietic Stem Cell Transplant Patients Predicts Day 100 Mortality

Background: Hematopoietic stem cell transplantation (HSCT) outcomes continue to improve, but there remains significant morbidity and mortality associated with this therapy. Acute kidney injury (AKI) has been shown to be an independent predictor of poor outcomes in many patient populations. Previous studies have demonstrated that development of AKI is associated with chronic renal disease and mortality in patients undergoing HSCT. We sought to determine the incidence of AKI in pediatric patients during the first 7 and 30 days following HSCT, and to examine the association between the presence of AKI and 100 day and 1 year survival.

Patients and Methods: We retrospectively reviewed data on 132 consecutive pediatric patients who received HSCT at Children’s Hospital of Alabama between 2000-2007. Autologous transplants were performed in 45 (34%) patients, and allogeneic transplants were from a matched related (19%) or unrelated (47%) donor source. Stem cell source was bone marrow (42%), peripheral blood (36%), or umbilical cord blood (22%).  Patients were classified as having AKI if they had either an increase in serum creatinine (SCr) ≥ 0.3 mg/dl from the baseline value over 7 days or ≥ 150% increase in SCr, in accordance with contemporary AKI definitions. Baseline SCr values for all patients were obtained during the pre-transplant evaluation. The incidence of AKI was determined at 7 and 30 days post-transplant. Measured outcomes were survival at day 100 and 1 year following HSCT.

Results: During the first 100 days following HSCT, 70 of 132 (53%) of patients met criteria for AKI. Donor source did not appear to influence the incidence of AKI; however patients receiving bone marrow stem cells had a higher incidence of AKI compared to other stem cell sources. 23 of 70 patients (33%) were diagnosed with AKI during the first week post-HSCT, with the remainder of patients meeting criteria within 2-4 weeks post-HSCT. Of those patients that developed AKI by 7 days post-HSCT, three of 23 patients (13%) died before 100 days following transplant and five of 23 (22%) died prior to 1 year post-transplant, which was not significant when compared to those patients without AKI. In comparison, for patients diagnosed with AKI by day 30, 14 of 70 patients (20%) died before 100 days following transplant, and 25 of 70 patients (35%) died prior to 1 year post-transplant. Statistical analysis revealed that presence of AKI at 30 days post-HSCT was associated with increased mortality at 100 days post-transplant (p=0.05), but not 1-year mortality.

Conclusions: This retrospective cohort study demonstrates that AKI is a common morbidity following HSCT for pediatric patients. Furthermore, we have shown that later development of AKI (by day 30) is associated with increased day 100 mortality. Future studies are planned to determine potential interventions to prevent or treat AKI, which could improve outcomes for this at-risk population.