Risk Factors for Severe Acute Kidney Injury after Pediatric Hematopoietic Stem Cell Transplantation

Background: Acute Kidney Injury (AKI) is common after Hematopoietic Stem Cell Transplantation (HSCT) and is associated with increased morbidity and mortality. Risk factors for AKI after HSCT are not fully understood, and there are limited pediatric studies that describe post HSCT AKI. Objective: To assess unique risk factors for AKI in the HSCT population. Design/Methods: We conducted a retrospective cohort study of patients < 20 years age who received an HSCT at Seattle Children’s Hospital from 10/1/2008 to 7/31/2017 (n=484). We defined AKI using Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Severe AKI was > KDIGO Stage 2. We collected information on demographics, baseline transplant characteristics (including conditioning regimen, donor type, cell source, indication for HSCT), post-HSCT complications (inotrope use, sepsis, ventilator use), and mortality at 1 year. Multinomial logistic regression was used to estimate the association between AKI and potential risk factors. We used adjusted cox proportional hazard ratios to evaluate differences in mortality between groups. Results: 186 patients (38%) developed AKI. Of those with AKI, 79 (42%) had severe AKI and 27 (15%) required renal replacement therapy (RRT). There were no significant differences in demographics and indication for HSCT between the groups. Fluid overload was common in all groups with 53 (67%) of those with severe AKI with a fluid overload>10%. Nephrology consult was obtained in fewer than 50% of those with severe AKI. Children who received a cord blood transplant or mismatched transplant had a higher relative risk of severe AKI on univariable analysis only. In both univariable and multivariable analysis, the risk of severe AKI was lower in those who had myeloablative conditioning (RR 0.65 (95% CI 0.3-0.99)) and those who received Tacrolimus (RR 0.42 (95% CI 0.11-0.73)). . Risk of mortality was 4.61 (2.61-8.15) times higher in severe AKI compared to no AKI. Conclusions: AKI and fluid overload are common in pediatric patients post HSCT. In our study, severe AKI was less frequent in those with received a myeloablative conditioning regimen or Tacrolimus and was associated with higher mortality. These risk factors could represent unique causes of AKI in this population that warrant further evaluation for use in predicting AKI after HSCT. Nephrology consultation was underutilized and often delayed.