Female gender and hyperfiltration: independent predictors of acute kidney injury after liver transplantation

Background: Acute kidney injury (AKI) after liver transplantation (LT), in particular stages 2–3, has recently been recognized to be important predictor for worse post-LT outcome and increased mortality. Risk factors for post-LT AKI are multiple and include pre-LT renal dysfunction, lower pre-LT serum creatinine (sCr) levels, higher MELD score, HCV infection, diabetes, intraop- erative haemodynamic instability, post-LT graft dysfunction and infections. Abnormally lower sCr values (<0.4 mg/dL) are frequent before LT, particularly in female, and are associated to hyperfiltration, not related to a better kidney function. Hyperfiltration has been recognized to be an important predictor of post-LT mortality. Aims of this study are to evaluate incidence and risk factors for AKI, its relation with hyperfiltration and its impact on patients’ survival. Methods: Retrospective single-centre study of 145 patients (117 M, 28 F) who underwent LT (January 2008–October 2015). We considered renal function from listing to transplant and within one week post-LT, functional recovery of the graft, intraoperative parameters. AKI defined and classified on the basis of KDIGO Guidelines (2012). Hyperfiltration defined as eGFR>120 ml/min/1,73 m2. Results: 22 out of 145 patients (15%) experienced post-LT AKI stages 2–3 (13/117M, 11.1%; 9/28F, 32.1%). Survival was significantly lower in patients with AKI stages 2–3 (42% vs. 58%, p = 0.001) (see Figure 1). The evaluation of risk factors on the univariate analysis evidenced female gender, lower pre-LT sCr, higher LAB-MELD and renal hyperfiltration as predictive factors for development of AKI stages 2–3. In the multivariable analysis, the independent predictors of development of AKI stages 2–3 were female gender (p = 0.020) and renal hyperfiltration (p = 0.045). Conclusion: We showed a significant increased mortality in patient develop- ing AKI post-LT. Female gender and renal hyperfiltration resulted independent predictors for development of AKI post-LT.