【Abstract】Objective To investigate the prevalence and risk factors of acute kidney injury (AKI) in patients after coronary artery bypass surgery (CABG). Methods In the period from September 2011 to November 2013, a total of 1,615 consecutive patients undergoing isolated CABG in Fuwai Hospital were enrolled in this retrospective study. Kidney Disease Improving Global Outcomes (KDIGO) diagnostic criteria were used to evaluate the kidney injury 7 days after surgery. Logistic regression model was used to analyze the potential risk factors for AKI. Results A total of 1,574 patients with complete clinical data were finally enrolled in this

study. The mean age of the patients was 60.3±8.4 years and 20.5% were females. Of the studied patients, 70.2% met the criteria for AKI, including 891 (56.6%) with AKI Ⅰ, 182 (11.6%) with AKI Ⅱ and 32 (2.0%) with AKI Ⅲ. Logistic regression analysis showed that age (OR=1.04, 95% CI 1.02～1.05, P＜0.001), cardiopulmonary bypass (OR=1.53, 95% CI 1.23～1.92, P＜0.001) and preoperative left ventricular ejection fraction (LVEF) <50% (OR=1.46, 95% CI 1.01～2.09, P=0.042) were the independent risk factors for postoperative AKI in CABG patients. In addition, CABG patients will be more likely to meet the AKI diagnostic criteria by KDIGO when their blood creatinine levels of the last preoperative measurements were lower (OR=0.98, 95%, CI 0.97～0.99, P＜0.001). Conclusion The higher incidence of postoperative AKI in CABG patients should be concerned by clinicians. Age, application of extracorporeal circulation and preoperative LVEF <50% are the independent risk factors for postoperative AKI in CABG patients. Patients with lower creatinine levels before bypass surgery were more likely to meet the AKI diagnostic criteria by KDIGO.