Predicting urine output after kidney transplantation: development and internal validation of a nomogram for clinical use

PURPOSE: To analyze pre-transplantation and early postoperative factors affecting post-transplantation urine output and develop a predictive nomogram. PATIENTS AND METHODS: Retrospective analysis of non-preemptive first transplanted adult patients between 2001-2016. The outcomes were hourly diuresis in mL/Kg in the 1(st) (UO(1)) and 8(th) (UO(8)) postoperative days (POD). Predictors for both UO(1) and UO(8) were cold ischemia time (CIT), patient and donor age and sex, HLA I and II compatibility, pre-transplantation duration of renal replacement therapy (RRT), cause of ESRD (ESRD) and immunosuppressive regimen. UO(8) predictors also included UO(1), 1(st)/0(th) POD plasma creatinine concentration ratio (Cr(1/0)), and occurrence of acute cellular rejection (AR). Multivariable linear regression was employed to produce nomograms for UO(1) and UO(8). RESULTS: Four hundred and seventy-three patients were included, mostly deceased donor kidneys’ recipients (361, 70.4%). CIT inversely correlated with UO(1) and UO(8) (Spearman's p=-0.43 and −0.37). CR(1/0) inversely correlated with UO(8) (p=-0.47). On multivariable analysis UO(1) was mainly influenced by CIT, with additional influences of donor age and sex, HLA II matching and ESRD. UO(1) was the strongest predictor of UO(8), with significant influences of AR and ESRD. CONCLUSIONS: The predominant influence of CIT on UO(1) rapidly wanes and is replaced by indicators of functional recovery (mainly UO(1)) and allograft's immunologic acceptance (AR absence). Mean absolute errors for nomograms were 0.08 mL/Kg h (UO(1)) and 0.05 mL/Kg h (UO(8)).