Clinical Significance Of Cystatin C In Patients With Severe Pneumonia Complicated With Renal Insufficiency

Objective To evaluate the significance of cystatin C in the early diagnosis of severe pneumonia complicated with acute kidney injury by detecting the dynamic changes of cystatin C in elderly patients.MethodsAccording to the IDSA / ATS diagnostic criteria for severe pneumonia,a retrospective study was conducted on 70 elderly patients aged 60-89years(excluding those with renal insufficiency at admission)and 20 elderly healthy volunteers aged 60-89 years in Dongfang Hospital from October 2018 to September 2019.The elderly pneumonia patients were divided into acute kidney injury(AKI)group and non AKI group according to Glomerular filtration rate(GFR).Venous blood samples were collected in the morning at d 1,d 3,d 5 and d 7 after patients enrollment to detect the levels of Cystatin-C,blood urea nitrogen(BUN)and serum creatinine(SCR).SPSS.25.0 software was used to analyze the test data.The dynamic changes of blood urea nitrogen,serum creatinine and cystatin C were analyzed and compared at different time points in healthy group,non AKI group and AKI group.The dynamic trends of urea nitrogen,serum creatinine and cystatin C in AKI group were analyzed.The changes of cystatin C at different time points in the three groups were analyzed and compared.The receiver operating characteristic curve(ROC)was used to analyze the changes of cystatin C in AKI group and non AKI group at each time point,and the area under the curve(AUC),sensitivity and specificity were calculated.The data of urea nitrogen,serum creatinine and cystatin C in AKI group and non AKI group at d 1 and d 3 were compared with GFR for ROC analysis,and the combination of cystatin C,urea nitrogen and serum creatinine in the diagnosis of AKI was made by logistic regression analysis.The data was compared with GFR for ROC analysis.Results1.The dynamic expressions of blood urea nitrogen,serum creatinine and cystatin C were compared at different time points among healthy group,non AKI group and AKI group.There were no significant different expression of blood urea nitrogen,serum creatinine and cystatin C among the healthy group and the non AKI group at d 1,d 3,d 5 and d 7(P > 0.05).Cystatin C in AKI group exhibited much higher than that in healthy group and non AKI group at each time point(P < 0.05).Serum creatinine and urea nitrogen in AKI group were significantly higher at d 3,d 5 and d7 than those in non AKI group and the healthy group(P < 0.05),while no significant diffrence in serum creatinine and urea nitrogen was found at d7(P < 0.05).2.The dynamic trends of urea nitrogen,serum creatinine and cystatin C were further analyzed in AKI group.It was found that cystatin C was significantly increased at d 1,but the serum creatinine and urea nitrogen were not significantly increased at d 1.Cystatin C increased sharply at d 3,d 5 and d 7.The concentration change of cystatin C in AKI group was significantly higher than the creatinine compared with its baseline at d 1,d 3,d 5 and d 7(P < 0.05),and moreover significantly higher than that of urea nitrogen(P < 0.05).This data indicated that cystatin C increased early on the first day till d 7,whereas serum creatinine and urea nitrogen did not increase at d 1,which may show that cystatin C had better diagnosis value on the 3rd,5th,7th day compared with serum creatinine and urea nitrogen.3.The change trend of cystatin C was compared in the three groups at different time points.It showed that cystatin C was within the normal range in healthy group and non AKI group,and there was no significant difference between that two groups(P > 0.05).Cystatin C in AKI group increased significantly at d 1,d 3,d 5 and d 7,which was significantly higher than that in healthy group and non AKI group(P < 0.05),and showed a rapid increase trend.4.ROC curve analysis showed that the area under curve(AUC)of cystatin C was 0.739,0.857,0.930 and 0.967 at d 1,d 3,d 5 and d 7 in predicting the diagnosis value for pheumonia patients with AKI,respectively.It showed that cystatin C at d 3 exhibited better sensitivity and specificity than that at d 1 for the early diagnosis of AKI,with an increased diagnosis value from d 3.5.ROC curve analysis showed that the AUC of cystatin C,serum creatinine and urea nitrogen at d 1 was 0.739,0.646 and 0.576 in predicting the diagnosis value for pheumonia patients with AKI,respectively.It showed that cystatin C exhibited better sensitivity and specificity than the serum creatinine and urea nitrogen for the early diagnosis of AKI.In addition,logistic regression analysis and ROC analasis were used to assess the combined diagnosis value of cystatin,urea nitrogen and serum creatinine.The AUC of the three comibined index was 0.787,indicating that that had better predicted effect early diagnosis value for pheumonia patients with AKI.6.ROC curve analysis showed that the AUC of cystatin C,serum creatinine and urea nitrogen at d 3 was 0.857,0.743 and 0.686 in predicting the diagnosis value for pheumonia patients with AKI,respectively.It showed that cystatin C exhibited better sensitivity and specificity than the serum creatinine and urea nitrogen for the diagnosis of AKI at d 3.In addition,logistic regression analysis and ROC analasis were used to assess the combined diagnosis value of cystatin,urea nitrogen and serum creatinine.The AUC of the three comibined index was 0.934,indicating that that had better predicted effect early diagnosis value for pheumonia patients with AKI.ConclusionCystatin C increased in the early course of the elderly severe pheumonia patients complicated with acute kidney injury.In addition,the dynamic monitoring of cystatin C demonstrated the diagnosis value for pheumonia patients with AKI.Moreover,cystatin C combined with urea nitrogen and serum creatinine had higher diagnostic value.