Effect of serum uric acid level on the incidence of acute kidney injury after off-pump coronary artery bypass grafting

Objective To investigate the effect of preoperative serum uric acid level on the incidence of acute kidney injury after off-pump coronary artery bypass grafting and to discuss whether serum uric acid level is an independent predictor of postoperative acute kidney injury. Methods A total of 631 patients undergoing off-pump coronary artery bypass grafting in Anzhen Hospital from January 2018 to June 2018 were reviewed. Patients were divided into high uric acid group(higher-than-median)and low uric acid group(lower-than-median) , based on the preoperative serum uric acid level of the patients. The demographic variables, comorbidities, the chelsea comorbidity index, preoperative medication, serum creatinine level and glomerular filtration rate were compared between the two groups. Meanwhile, intraoperative operative time, infusion volume, postoperative acute kidney injury staging and the rate of frozen plasma usage, continuous renal replacement therapy and reoperation rate were observed. Results Among the 631 patients, 83(13.2%, 83/631)cases developed postoperative acute kidney injury, 65(78.3%, 65/83) cases had a higher level of preoperative serum uric acid above the median(OR=3.143, 95%CI: 1.850-8.798, P=0.001). After adjustment, multivariate analysis showed that elevated level of serum uric acid and BMI>30 kg/m2, the increase of preoperative serum creatinine level, the decrease of glomerular filtration rate(<60 ml/min) and higher CCI score were associated with postoperative acute kidney injury independently. Intraoperative fluid volume, diabetes and preoperative diuretic administration did not relate to the incidence of acute kidney injury after cardiac surgery. Conclusion Elevated serum uric acid level can be a strong predictor for the incidence of acute kidney injury after off-pump coronary artery bypass grafting. Key words: Off-pump coronary artery bypass grafting; Serum uric acid level; Acute kidney injury