Incidence, Risk Factors and Outcome of Postoperative Acute Kidney Injury in China

Abstract Background and hypothesis Postoperative acute kidney injury (AKI) is a common condition after surgery, however, the available data about nationwide epidemiology of postoperative AKI in China from the large and high-quality studies is limited. This study was aimed to determine the incidence, risk factors, and outcomes of postoperative AKI among patients undergoing surgery in China. Methods This was a large, multicenter, retrospective study performed in 16 tertiary medical centers in China. Adult (at least 18 years old) patients who undergoing surgical procedures from January 1, 2013 to December 31, 2019 were included. Postoperative AKI was defined by the Kidney Disease: Improving Global Outcomes creatinine criteria. The associations of AKI and in-hospital outcomes were investigated using logistic regression models adjusted for potential confounders. Results Among 520 707 patients included in our study, 25 830 (5.0%) patients developed postoperative AKI. The incidence of postoperative AKI varied by surgery type, which was highest in cardiac (34.6%) surgery, followed by urologic (8.7%), and general (4.2%) surgeries. 89.2% postoperative AKI cases were detected in the first 2 postoperative days. However, only 584 (2.3%) patients with postoperative AKI were diagnosed with AKI on discharge. Risk factors for postoperative AKI included advanced age, male sex, lower baseline kidney function, pre-surgery hospital stay ≤ 3 days or > 7 days, hypertension, diabetes mellitus, and use of PPIs or diuretics. The risk of in-hospital death increased with the stage of AKI. In addition, patients with postoperative AKI had longer length of hospital stay (12 vs 19 days), were more likely to require intensive unit care (13.1% vs 45.0%) and renal replacement therapy (0.4% vs 7.7%). Conclusions Postoperative AKI was common across surgery type in China, particularly for patients undergoing cardiac surgery. Implementation and evaluation of an alarm system is important for the battle against postoperative AKI.