Predictors of end-stage renal disease after cardiac surgery

Introduction Cardiac surgery associated acute kidney injury (CSI AKI) is severe complication. Incidence in literature varies up to 30%. In 2-5% of AKI patients introducing renal replacement therapy (RRT) is necessary and they are prone to development of a terminal renal failure. Aim of this study was to analyse incidence of AKI in our institution, compare to literature and benchmark institutions and define probably perioperative variables that are manageable and could be altered in order to reduce incidence of AKI. In order to analyse perioperative factors that can cause development of end-stage renal disease (ESRD) we collected data from Croatian Institute of Public Health (CIPH) registry of chronic renal disease and connected with our data. Methods Study design: a single centre retrospective observational study. Institutional board of Clinic Magdalena as well as Ethical Board of CIPH approved the study. There were 2181 heart operation in our institution during period 2013-2017. Eligible for study (all data collected) were 1817 patients. Categorical variables were analysed using Pearson Chi-square test, continuous variables were analysed using an unpaired T-test. The p value below 0.05 was considered statistically significant. AKIN classification was used for diagnosis of AKI. Results Data was collected from 1817 patients; 303 (16,6%) patients developed some kind of AKI; stage I 258 (85%), stage II 38 (12,5%) and stage III 9 patients (2,97%). Overall mortality was 1,98% (36) and in AKI group 5,28% (16). Thirteen patients developed ESRD (0,71%), 5 of them had AKI during hospitalisation (stage I 4, and stage III 1 patient). We found age, body mass index (BMI), Euroscore II score, cerebrovascular disease, pre-existing renal disease, peripheral vascular disease, hypertension, haemoglobin (Hb), haematocrit (Htc) and C reactive protein level to be preoperative variables related to development of AKI. Intraoperative variables with statistically significant difference among groups are operating time and clamp time. As for variables related to development of ESRD we found preoperative Hb and Htc level as well as preoperative creatinine clearens (CrCl), pre-existing renal disease, diabetes mellitus, and atrial fibrillation to be statistically significant. Discussion Discussion: Our data are comparable with literature data. Interestingly both level of Hb and Htc are variables related to development of AKI as well as ESRD after cardiac surgery. It seems that preoperative correction of anaemia and intraoperative meticulous blood management, among others perioperative tactics, could lead to reduction of incidence of AKI and ESRD after cardiac surgery.