Acute Kidney Injury (AKI)

AKI was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines [38] as an increase in serum creatinine (SCr) ≥26.5 μmol/l within 48 h or an increase in SCr ≥1.5 the baseline value within 7 days [24]. The baseline was defined as kidney function represented by SCr and dependence on KRT on the date of OLT before transplantation (POD 0). Therefore, patients with pre-transplant AKI and acute chronic kidney disease were included in the study. Patients undergoing KRT before OLT were excluded from the AKI analysis. According to KDIGO classification, AKI was subsequently subdivided into Stage 1: rise in SCr of ≥26.5 μmol/l within 48 h or a rise of 1.5–1.9 times baseline; Stage 2: rise in SCr of 2.0–2.9 times baseline; Stage 3: rise in SCr to ≥3.0 times baseline or increase to ≥353.6 μmol/l or need for KRT [38]. Urine output was not available at all collection times and consequently was not used for this study. Resolution of AKI on POD 30 was defined as the absence of AKI criteria and survival on POD 30 in patients with AKI on POD 1–7. Patients with KRT on POD 0 met the definition of AKI resolution when they were without KRT on POD 30. No resolution of AKI on POD 30 was defined as persistent KRT; SCr >353.6 μmol/l; SCr POD 30 divided by SCr POD 0 ≥1.5; died.