Acute Kidney Injury in Allogeneic Hematopoietic Transplant Recipients

Abstract

<h3>Background</h3> The reported incidence of acute kidney injury (AKI) after allogeneic hematopoietic cell transplantation (allo-HCT) varies from 10 to 73%. The association between GVHD, calcineurin inhibitors (CNIs) and risk for kidney injury remains controversial. We sought to describe the incidence of AKI and identify modifiable risk factors in large cohort of patients undergoing allo-HCT in our institution. <h3>Methods</h3> All consecutive patients undergoing allo-HCT from 2014 to 2017 in our institution were included. Pre-HCT variables including patient and graft characteristics, as well as post-HCT variables, including nephrotoxic medication exposure, ICU admission, and CNI levels were analyzed in association with AKI. AKI was defined using KDIGO criteria, grades 1, 2 and 3, through post-transplant day 100. Severe AKI was defined as grades 2 or 3. Differences across groups were assessed using either Wilcoxon rank-sum tests or Fisher's exact tests. AKI risk factors were estimated using cause-specific Cox proportional hazards regression. <h3>Results</h3> A total of 616 patients underwent allo-HCT during the study period. Median age was 58 (19-79) years, 59% male, 83% Caucasian. Indication for HCT was leukemia in 49%, myelodysplastic syndrome in 16%, and lymphoma in 17%. Median baseline creatinine was 0.8 (0.3-2.7) mg/dL. Median age-adjusted HCT-comorbidity index was 3 (range 0-9). Median baseline albumin was 3.5 (IQR 3.3-3.8) mg/dL and BMI 27.2 (IQR 23.8-30.8). Incidence of acute GVHD was 47%, and 60 patients had severe (grades 3-4) GVHD. Bacteremia occurred in 19% of patients. Amphotericin preceded max-grade AKI in 3.1%, cidofovir in 0.8%, and Foscarnet in 4.4% of patients. Median tacrolimus level preceding AKI was 7.88 (range 4.2-23.2) mg/dL. By day 100 post-HCT, 403 (65.4%) had any AKI, 220 (35.7%) patients had grade 1 AKI, 119 (19.3%) grade 2 AKI, and 64 (10.4%) grade 3 AKI; 19 (3.1%) required hemodialysis. Median time to AKI was 17 (IQR 8-35) days, and median time to max-grade AKI was 31 (IQR 13-53) days. Ex vivo CD34-selected HCT patients had a lower risk for AKI, hazard ratio 0.46 (0.35-0.62), p<0.001 (Table 1). <h3>Conclusion</h3> AKI in patients undergoing allo-HCT remains a major concern, affecting 65.4% of patients, with grade 2 and 3 AKI occurring in 19.3% and 10.4%, respectively. Patients receiving CNIs including tacrolimus have a significantly higher risk for AKI, whereas patients undergoing CD34-selected allo-HCT have a lower risk of AKI. The effect of AKI after HCT on long-term kidney function requires further prospective study.