Evaluation Of Laboratory Diagnosis Performance For Acute Kidney Injury In Patients With Liver Cirrhosis

Objective: By detecting the levels of neutrophils associated apolipoprotein in serum(s NGAL)and urine(u NGAL),cystatin C(Cys C),and serum creatinine(s Cr)in liver cirrhosis patients with or without secondary acute kidney injury(AKI)and healthy controls,to statistically analyze the correlations between s NGAL/u NGAL,Cys C/Cys C-e GFR(calculated base on Cys C)and s Cr/c-a GFR(calculated base on s Cr),as well as to investigate the effectiveness of these parameters as biomarkers for predicting the development of AKI in liver cirrhosis patients.Methods: A total of 573 subjects who came to Mianyang Central Hospital for medical consultations and physical examination were recruited into this study from January 2015 to September 2016,including 286 patients with simple liver cirrhosis(group SLC),181 patients with cirrhosis secondary to acute renal impairment(AKI)(group LC-AKI)and 106 healthy subjects(group HC).About 5ml of the fasting venous blood was drawed in the morning,and then about 10 ml of middle urine was collected.Serum creatinine levels were detected by muscle ammonia oxidase method and the levels of s NGAL,u NGAL and Cys C/Cys C-e GFR were detected by transmission turbidimetry.Corresponding estimated glomerular filtration rates(e GFR)named as c-a GFR and Cys C-e GFR were respectively calculated base on s Cr and Cys C.The differences and correlation between the observed parameters(including s NGAL,u NGAL and Cys C/Cys C-e GFR)and the traditional biomarker-s Cr/c-a GFR were statistically analyzed among the various groups.Logistic regression and the receiver-operating characteristic curve(ROC)analysis were finally performed to investigate the diagnostic accuracy of single or joint use of the biomarkers for the diagnosis of AKI in patients with liver cirrhosis.Results:(Ⅰ)Results of Kruskal-wallis test showed that the levels of various biomarkers were significantly different among HC,SLC and LC-AKI groups(χ2=271.035 ~ 326.275,all P<0.001).Compared with SLC and HC groups,the levels of s NGAL(z=16.115 and 14.143),u NGAL(z=16.308 and 14.589),s Cr(z=14.875 and 14.246)and Cys C(z=14.522 and 13.728)in LC-AKI group were significantly elevated(all P<0.001),while the levels of c-a GFR(z=-14.525 and-14.648)and Cys C-e GFR(z=-14.522 and-13.728)were markedly decreased(all P<0.001).(Ⅱ)Jonckheere-Terpstra test suggested that along with the progression of AKI stages,the levels of s NGAL(z=4.741)、u NGAL(z=5.695)、s Cr(z=12.963)and Cys C(z=11.245)in the patients in the LC-AKI group were increasing(all P<0.001),while the levels of c-a GFR(z=-12.712)and Cys C-e GFR(z=-11.241)were decreasing(all P<0.001).(Ⅲ)Results of Spearman’s correlation analysis indicated that the levels of s NGAL,u NGAL and Cys C were positively correlated with traditional biomarker-s Cr(r=0.659,0.669 and 0.713,all P<0.001),on the contrary,Cys C-e GFR was negatively correlated with s Cr(r=-0.713,P<0.001). Meanwhile,the levels of s NGAL,u NGAL and Cys C were negatively correlated with c-a GFR(r=-0.647,-0.667 and-0.727,all P<0.001),whereas Cys C-e GFR was positively correlated with c-a GFR(r=0.727,P<0.001).(Ⅳ)ROC curve analysis in the diagnosis of AKI in patients with liver cirrhosis revealed that the area under curve(AUC)and its 95% confidence interval(CI)of each observed biomarker-s NGAL,u NGAL,s Cr,Cys C,c-a GFR and Cys C-e GFR was 0.958(0.938~0.973),0.966(0.947~0.979),0.934(0.910~0.953),0.922(0.897~0.943),0.931(0.907~0.950)and 0.922(0.897~0.943),respectively.The sensitivity(Se)was 93.9%,97.2%,91.7%,87.8%,87.8% and 87.8%,and the specificity(Sp)was 91.6%,92.1%,79.8%,93.1%,82.7% and 93.1%.When the value of Youden Index(YI)were maximum,the corresponding concentrations of each observed biomarker that were used as the judgment line were respectively 109μg/L,41μg/g Cr,76.8μmol/L,1.29mg/L,96.1ml/min/1.73m2 and 61.1ml/min/1.73m2.In this case,the diagnostic effectiveness of u NGAL was maximum(0.893),followed by s NGAL(0.855).Moreover,the AUC of u NGAL was the largest(0.966),and was significantly higher than that of s Cr(z=3.526,P<0.001),Cys C(z=2.746,P=0.006),c-a GFR(z=3.407,P<0.001)and Cys C-e GFR(z=2.746,P=0.006).However,there was no significant difference when compared with that of s NGAL(z=1.116,P=0.244).As expected,the AUC of s NGAL(0.958)was much higher than that of s Cr(z=2.277,P=0.023),Cys C(z=2.140,P=0.032),c-a GFR(z=2.329,P=0.020)and Cys C-e GFR(z=2.140,P=0.032),presenting marked difference.(Ⅴ)Binary Logistic regression analysis indicated that Cys C and c-a GFR were excluded due to the regression coefficient P value above 0.10,while s NGAL(B=0.0073,Wald χ2=18.105,P<0.001),u NGAL(B=0.0201,Wald χ2=14.694,P<0.001),s Cr(B=0.0202,Wald χ2=4.404,P=0.036)and Cys C-e GFR(B=0.0340,Wald χ2=9.853,P= 0.002)were closely related to LC-AKI patients,and included to establish the logistic regression equation respectively: 1LogitsGFRCys CCr Pus NGALNGALe-×+×+-×-×=-6570.20073.00201.00360.00165.0(Nagelkerke R2=0.803,P<0.001)P2LogitsCGALe GFRys CCr-×+-×-×=-4107.20340.00381.00202.0 u N(Nagelkerke R2=0.782,P<0.001)P3LogitCs Cr-×+-×-×=-es NGALGFRCys9771.10113.00431.00217.0(Nagelkerke R2=0.787,P<0.001)The area under curve(AUC)and its 95% confidence interval(CI)of each logistic regression equation(Logit-P1、Logit-P2 and Logit-P3)was 0.976(0.960~0.987),0.973(0.956~0.985)and 0.973(0.956~0.985),respectively.Results of Delong test showed no significant difference among the three AUC(95%CI)[Logit-P1 vs.Logit-P2 vs.Logit-P3: z=0.003~1.862,P=0.063~0.997].The diagnostic sensitivity,specificity and efficiency of Logit-P1,Logit-P2 and Logit-P3 were(100.0%,93.1% and 92.2%),(99.4%,93.1% and 92.8%)and(97.8%,93.4% and 92.0%),respectively.(Ⅵ)ROC curve analysis was performed to investigate the diagnostic values of the combined detection of two(s NGAL/u NGAL,s NGAL/s Cr,s NGAL/Cys C-e GFR,u NGAL/s Cr,u NGAL/Cys C-e GFR and s Cr/Cys C-e GFR)or three biomarkers(s NGAL/ u NGAL/s Cr,s NGAL/u NGAL/Cys C-e GFR,s NGAL/s Cr/Cys C-e GFR,and u NGAL/s Cr/Cys C-e GFR),and the three Logistic regression equations.AUC of each logistic regression equation(Logit-P1、Logit-P2 and Logit-P3)was 0.976,0.973 and 0.973 respectively,and there was no statistically significant difference between each other(z=0.003~1.862,P=0.063~0.997).The sensitivity of them were respectively 100.0%,99.4% and 97.8%,and the specificity of them were 93.1%,93.1% and 93.4%.In addition,results of ROC curve analysis revealed that the logistic regression equations had better diagnostic performance(AUC=0.973~0.976)than the combined measurement of any two(AUC=0.949~0.956)or three(AUC=0.938~0.956)biomarkers(z=2.574~4.558,all P<0.05).Otherwise,no statistically significant difference was found in the diagnostic performance between any two or three combined biomarkers measurement(z=0.000~1.954,all P>0.05).(Ⅶ)In patients with liver cirrhosis,AKI staging is different from its Child-Pugh classification.Although the difference was statistically significant(χ2=56.433,P<0.001),the relationship of them was close(γ=0.481,P<0.001).In different Child-Pugh classification patients with liver cirrhosis,u NGAL abnormalities occur in all Child-A and Child-B subjects,indicating that u NGAL has the highest prediction value of LC-AKI risk(OR=337.659,540.500 and 332.500,all P<0.001).Nevertheless,in Child-C patients,s NGAL present the highest risk prediction value of LC-AKI(OR=179.182,P<0.001).Conclusion:(Ⅰ)The levels of s NGAL,u NGAL and Cys C were significantly different among HC,SLC and LC-AKI groups.Especially in the LC-AKI group,the levels all strikingly elevated,suggesting that these parameters have high sensitivity and specificity for diagnosis of the development of AKI in the patients with liver cirrhosis.(Ⅱ)The levels of s NGAL,u NGAL and Cys C are positively correlated with the severity of AKI in patients with liver cirrhosis.(Ⅲ)Biomarkers of s NGAL,u NGAL and Cys C take a collaborative approach for diagnosis of AKI in patients with liver cirrhosis,which are positively correlated with the s Cr and negatively correlated with c-a GFR.(Ⅳ)By using single marker detection,NGAL may be more reliable than Cys C and s Cr for early diagnosis of the development of AKI in patients with liver cirrhosis.(Ⅴ)Combined detection of u NGAL,s Cr and Cys C-e GFR is preferred to raise the clinical diagnostic coincidence rate with extremely important clinical significance.(Ⅵ)Among patients with liver cirrhosis grading Child-Pugh A and B,u NGAL performed better than other indexes for the prediction of AKI.In addition,s NGAL is the best biomarker for early diagnosis of AKI in subjects with liver cirrhosis grading Child-Pugh C.