Objective To investigate the prognosis and risk factors of cardiac surgical patients with preoperative renal dysfunction，and evaluate the accuracy of estimated glomerular filtration rate （eGFR） as a predictor of adverse outcomes. Methods A total of 2 151 adult patients undergoing cardiac surgery in Renji Hospital，School of Medicine of Shanghai Jiaotong University from January 2005 to December 2009 were included in this study. There were 1 267 male patientsand 884 female patients with their average age of 58.7 （18-99）years. Clinical characteristics of patients with preoperative renal dysfunction，severity of postoperative acute kidney injury （AKI）and patients’ outcomes were analyzed. Multivariate logistic regression was performed to analyze perioperative risk factors of postoperative AKI. Receiver operating characteristic（ROC） curve was used to evaluate the accuracy of eGFR to predict patients undergoing postoperative renal replacement therapy （RRT） and in-hospital death. Results A total of 221 patients （10.27%） had preoperative renal dysfunction，among whom 124 patients （56.11%） developed postoperative AKI. Patients with preoperative renal dysfunction were older，had more comorbidities including hypertension and diabetes mellitus，were more likely to receive postoperative RRT，and had worse outcomes. Patients with decreased preoperative eGFR had significantly higher in-hospital mortality. Patients with preoperative renal dysfunction who developed postoperative AKI had the worst prognosis. Multivariate logistic regression showed that hypertension （OR=4.497，P=0.003），postoperative central venous pressure （CVP） ＜6 cm H2O （OR=16.410，P=0.000） and postoperative CVP＞14 cm H2O （OR= 5.178，P=0.013） were independent predictors of postoperative AKI for patients with preoperative renal dysfunction. The areas under the ROC curves of eGFR to predict in-hospital mortality and postoperative RRT were 0.691 and 0.704 respectively （95% CI 0.630-0.752，P=0.000；95% CI 0.614-0.795，P=0.001）. Conclusion Patients with preoperative renal dysfunction are older，have more comorbidities，higher likelihood to develop postoperative AKI and worse prognosis. Hypertension，postoperative CVP＜6 cm H2O and postoperative CVP＞14 cm H2O are independent predictors of postoperative AKI for patients with preoperative renal dysfunction. We believe eGFR can accurately predict the risk of adverse kidney outcomes and in-hospital death of patients undergoing cardiac surgery.
Abstract： Objective To evaluate the incidence and prognosis of postoperative acute kidney injury （AKI） in patients after cardiovascular surgery， and analyse the value of AKI criteria and classification using the Acute Kidney Injury Network （AKIN） definition to predict their in-hospital mortality. Methods A total of 1 056 adult patients undergoing cardiovascular surgery in Renji Hospital of School of Medicine， Shanghai Jiaotong University from Jan. 2004 to Jun. 2007 were included in this study. AKI criteria and classification under AKIN definition were used to evaluate the incidence and in-hospital mortality of AKI patients. Univariate and multivariate analyses were used to evaluate preoperative， intraoperative， and postoperative risk factors related to AKI. Results Among the 1 056 patients， 328 patients（31.06%） had AKI. In-hospital mortality of AKI patients was significantly higher than that of non-AKI patients （11.59% vs. 0.69%， P＜0.05）. Multivariate logistic regression analysis suggested that advanced age （OR=1.40 per decade）， preoperative hyperuricemia（OR=1.97）， preoperative left ventricular failure （OR=2.53）， combined CABG and valvular surgery （OR=2.79）， prolonged operation time （OR=1.43 per hour）， postoperative hypovolemia （OR=11.08） were independent risk factors of AKI after cardiovascular surgery. The area under the ROC curve of AKIN classification to predict in-hospital mortality was 0.865 （95% CI 0.801-0.929）. Conclusion Higher AKIN classification is related to higher in-hospital mortality after cardiovascular surgery. Advanced age， preoperative hyperuricemia， preoperative left ventricular failure， combined CABG and valvular surgery， prolonged operation time， postoperative hypovolemia are independent risk factors of AKI after cardiovascular surgery. AKIN classification can effectively predict in-hospital mortality in patients after cardiovascular surgery， which provides evidence to take effective preventive and interventive measures for high-risk patients as early as possible.