Contribution of Acute Kidney Injury After Liver Transplant in Development of Chronic Kidney Disease: A Single-Center Retrospective Cohort Study

BACKGROUND: Acute kidney injury (AKI) is common after liver transplant and associated with increased morbidity and mortality. Transplantation of nonrenal organs is also associated with eventual chronic kidney disease (CKD). Development of CKD after liver transplant is known to be multifactorial; however, this study evaluates the unique contribution of AKI in this complex disease pathway. METHODS: Patients were classified into 2 groups: presence or absence of severe AKI within 72 hours postoperatively. Kidney function was assessed at year 1: normal/mild (estimated glomerular filtration rate [eGFR] ≥60 mL/min/1.73 m 2 ); moderate (30 ≤eGFR <60 mL/min/1.73 m 2 ); or severe (eGFR <30 mL/min/1.73 m 2 ) disease. Adjusted relative risks of both CKD and death at years 1 through 3 in the presence versus absence of severe AKI were estimated using discrete-time targeted maximum likelihood estimation. RESULTS: Of 1574 patients, 769 (49%) experienced severe AKI. At year 1, 1024 (65%) patients had normal/mild, 487 (31%) had moderate, and 63 (4%) had severe CKD. The unadjusted relative risk of severe CKD was 3.66 (95% confidence interval [CI], 2.15-7.33), and the adjusted relative risk was 2.62 (95% CI, 1.61-4.28) in patients with severe AKI. In total, 66 (4%), 115 (7%), and 147 (9%) patients died in years 1, 2, and 3, respectively. Patients with severe AKI had an unadjusted relative risk of death at year 1 of 2.41 (95% CI, 1.47-4.19) compared to an adjusted relative risk of 1.15 (95% CI, 1.04-1.28); at year 2, the unadjusted relative risk of death was 1.51 (95% CI, 1.07-2.19) compared to an adjusted relative risk of 1.14 (95% CI, 1.04-1.25); and at year 3, the unadjusted relative risk of death was 1.44 (95% CI, 1.05-1.97) compared to an adjusted relative risk of 1.13 (95% CI, 1.04-1.23). CONCLUSION: Severe postoperative AKI is associated with an increased risk of severe CKD at 1 year and mortality up to 3 years after liver transplant. Postoperative AKI represents an important target for future perioperative interventions aimed at mitigating the risk of long-term morbidity and mortality for liver transplant patients.