The Association Between Serum Uric Acid Levels And Mortality In Patients With Acute Kidney Injury

Objective:Acute kidney injury(AKI)is a common and serious clinical syndrome,with high morbidity and mortality,which usually diagnosed by urine output and serum creatinine.In addition,survivors often require long-term dialysis because their kidney function has not recovered,posing a huge financial burden.So,it is particularly important to explore the risk factors of death from AKI.Hyperuricemia can lead to an increased incidence of AKI in hospitalized patients,but few researches have pointed to their effect of uric acid levels on the prognosis of patients with AKI.This study aims to perform a retrospective analysis of hospitalized patients with AKI in our hospital to evaluate the relationship between serum uric acid(SUA)and mortality in AKI patients.Method:This study is a single-center retrospective study involving AKI inpatients from the Affiliated Hospital of Qingdao University from January 2015 to July 2020.Retrospectively collected clinical data onto patients using the medical data platform combined with electronic medical records.The study population was divided into the following 4 groups according to the quartile of SUA level,Q1: ≤ 3.6 mg/d L;Q1: > 3.6-5.1 mg/d L;Q1: > 5.1-6.9 mg/d L;Q4: > 6.9 mg/d L.A logistic regression model was used to evaluate the association for different SUA level groups and clinical outcomes in AKI patients.Subgroup analyses were performed to explore the differences in the association for hyperuricemia and in-hospital mortality in different subgroups.Receiver operating characteristic(ROC)curves were used to determine the predictive value of SUA for mortality in AKI patients.Result:A total of 4646 patients with acute kidney injury were finally included in this study,among which 358 patients(7.7%)died during hospitalization.The unadjusted logistic regression analysis showed that,the Q3 group(OR 1.67,CI 1.16-2.39;P = 0.006)and the Q4 group(OR 3.64,CI 2.62-5.05;P < 0.001)had a higher mortality rate compared with the control group Q1.After adjusting to the age,sex,and body mass index,the adjusted ORs(95% CI)were 1.46(1.01-2.12)and 3.16(2.25-4.45)in the Q3 and Q4 groups,respectively.After adjusting to confounders,the Q3(OR 1.72,CI 1.21-2.33;P = 0.006)and Q4(OR 2.75,CI 1.78-4.26;P < 0.001)groups were associated with an increased risk of in-hospital mortality in AKI patients.The unadjusted logistic regression analysis showed that,the non-recovery rate of renal function was higher in the Q4 group(OR 1.51,CI 1.12-2.01;P = 0.012)compared with the control group Q1.The adjusted OR(95% CI)was1.59(1.07-1.98)in the Q4 group compared with the control group Q1 after adjusting to age,sex,and body mass index.After adjusting to confounders,the Q4 group(OR 1.46,CI1.25-1.85;P < 0.001)was associated with an increased non-recovery rate of renal function of AKI patients.In subgroup analyses,significant interactions were observed between age(P < 0.001),gender(P < 0.001),AKI stage(P < 0.001),uric-lowering agents,and diabetes mellitus(P < 0.001)subgroups.Patients with higher AKI stages are more likely to die.Likewise,the risk of in-hospital mortality with higher SUA levels was significantly increased to patients with age ≥65 years(OR,1.20;95% CI,1.12-1.28),female(OR,1.27;95% CI,1.16-1.39),no urate-lowering drugs(OR,1.19;95% CI,1.13-1.25),and diabetes(OR,1.31;95% CI,1.18-1.45).In the ROC curve,the sensitivity was 51%,and the specificity was 73%,when the area under the ROC curves for uric acid to predict the mortality of AKI patients reached the maximum value(0.65).Inclusion of age in the ROC curves showed that age had predictive value of in-hospital mortality in AKI patients(P <0.001).In addition,we combined serum uric acid level with age to predict in-hospital mortality in AKI patients,and the results showed that the ROC curves area and sensitivity increased to 0.74 and 64%,respectively.Conclusion:1.Higher levels of SUA were associated with an increased risk of in-hospital mortality,and associated with an increased risk of non-recovery of renal function of AKI patients.2.SUA is an independent predictor of death in AKI patients.3.It will may be beneficial to AKI hyperuricemia patients to administer the uratelowering drugs.