Correlation Analysis Between Early Serum Uric Acid Concentration And Acute Kidney Injury After Coronary Artery Bypass Grafting

[Objective]To evaluate whether early postoperative serum uric acid(UA)level predict postoperative acute renal injury(AKI)among patients undergoing coronary artery bypass grafting(CABG).[Methods]The study prospectively enrolled 1306 patients undergoing coronary artery bypass grafting(CABG)in Fuwai Hospital between September of 2012 and December of 2013.The patients were divided into 5 groups by the concentrations of serum uric acid measured on the morning of the first postoperative day(6-12h after operation,the average time is 10h),and uric acid categories were as follow:less than 195 a mol/L,195-236 a mol/L,237-280 a mol/L,281-336 ?mol/L,more than 336 ? mol/L.The primary end points were AKI(RIFLE criteria),severe AKI(AKI?I),postoperative continuous renal replacement therapy(CRRT)requirement,in-hospital death,length of stay in hospital and ICU.The area under the receiver-operating characteristic curve(ROC-AUC)was used to determine the ability of the early postoperative serum uric acid level as a risk factor for postoperative AKI prediction.[Results]Among the 1306 patients enrolled in the study,AKI was found in 335 patients(25.65%).The incidence of AKI of group 1 through 5 were 17.2%,17.1%,21.9%,26.4%,45.8%,the incidence of AKII were 3.4%,2.7%,4.2%,4.6%,14.2%,and the incidence of CRRT were 0%,0.4%,0.8%,0.8%,2.3%,respectively.We adjusted for covariates including gender and age of patients,previous myocardial infarction,heart failure,preoperative use of diuretics,preoperative EF,baseline creatinine,baseline eGFR,intraoperative CPB,cardiopulmonary bypass time and aortic clamping time.Compared with the lowest UA quintile,the group 5 had significantly higher risk of AKI,AKI?I and the requirement of CRRT(P<0.01).Compared with the Q1 group,the odds ratios(ORs)of postoperative adverse events in the Q5 group were:AKI 2.58(95%CI:2.06-3.07),AKI?1 4.22(95%CI:3.73-4.71);Compared with the Q2 group,the odds ratio(OR)of the Q5 group for postoperative CRRT was 8.36(95%CI:7.85-8.86).The ROC for the outcome of postoperative AKI had an AUC of 0.648(95%CI:0.612-0.683)when serum crieatinine levels alone were used and 0.722(95%CI:0.688-0.755)when serum UA levels alone were used.Early postoperative serum UA was a better predictor than serum creatinine.[Conclusions]The serum uric acid concentration within 12 hours after operation is an independent predictor of postoperative AKI in patients undergoing CABG,which could be used to identify patients at high risk for AKI,so as to facilitate early intervention and improve prognosis.