Construction And Evaluation Of A Non-invasive Diagnostic Model For IgA Nephropathy With Different Clinical Manifestations

Objective:To explore the clinical indicators related to the diagnosis of IgA nephropathy,and to establish a non-invasive diagnostic model for IgA nephropathy with clinical manifestations of chronic nephritis syndrome and nephrotic syndrome.Methods:Patients admitted to the Department of Nephrology of The Affiliated Hospital of Qingdao University from June 1,2012 to June 30,2019 were selected.Patients with chronic nephritis syndrome or nephrotic syndrome diagnosed by renal biopsy were enrolled in our study.They were assigned into training set and validation set based on the enrolled time.The data of patients with IgA nephropathy and non-IgA nephropathy in the training set were compared.These data included general data(age,sex,history of hypertension,gross hematuria),serological tests(23 tests including serum albumin,serum creatinine,serum IgA,serum IgG,serum complement C3)and urine tests(count of urinary erythrocyte,24-hour urine protein quantification).The factors with p<0.05 were included in the receiver operating characteristic curve(ROC)analysis to screen factors related to the diagnosis of IgA nephropathy and establish the diagnositic model.Then,the model was validated in the validation set.Results:1.First part:(1)According to ROC curve analysis and logistic regression analysis,count of urinary erythrocyte,level of total protein,blood low density lipoprotein cholesterin,serum IgG and ratio value of IgA/C3 were selected as predictors for the diagnosis of IgA nephropathy manifested with chronic nephritis syndrome.(2)Based on the above indicators,a non-invasive diagnostic model for IgA nephropathy with clinical manifestations of chronic nephritis syndrome was established.In the training set,the area under the ROC curve of the model was 0.88(95%CI =0.84～0.92),the best diagnostic threshold was 0.50,the diagnostic sensitivity was 83.67%,the diagnostic specificity was79.66%,the positive predictive value was 83.67%,the negative predictive value was79.48%.In the validation set,the area under the ROC curve of the model was 0.84(95% CI=0.78～0.89),the diagnostic sensitivity was 79.55%,the diagnostic specificity was 73.56%,the positive predictive value was 76.53%,the negative predictive value was 83.11%.2.Second part:(1)According to ROC curve analysis and logistic regression analysis,count of urinary erythrocyte,level of serum creatinine and ratio value of IgA/ C3 were selected as predictors for diagnosis of IgA nephropathy with nephrotic syndrome.(2)Based on the above indicators,a non-invasive diagnostic model of IgA nephropathy with clinical manifestations of nephrotic syndrome was established.In the training set,the area under the ROC curve of the model was 0.88(95%CI =0.83～0.93),the best diagnostic threshold was 0.27,the diagnostic sensitivity was 76.90%,the diagnostic specificity was 87.50%,the positive predictive value was 66.67%,the negative predictive value was 92.11%.In the validation set,the area under the ROC curve of the model was 0.94(95% CI=0.88～0.99),the diagnostic sensitivity was 84%,the diagnostic specificity was 96.20%,the positive predictive value was 87.50%,the negative predictive value was 95%.3.Third part: Compared with patients with chronic nephritis syndrome,patients with nephrotic syndrome had an older age,a higher incidence of hypertension,and a lower incidence of gross hematuria.Compared with patients with chronic nephritis syndrome,patients with nephrotic syndrome had higher level of systolic pressure,diastolic pressure,24 hours urinary protein quantification,urea nitrogen,serum creatinine,blood triglycerides,total cholesterol,high-density lipoprotein cholesterol,low density lipoprotein cholesterol,blood lactic dehydrogenase,blood fibrinogen,blood D-dimer,serum IgE,and serum complement C4(all P < 0.05).The levels of total protein,albumin,total bilirubin,direct bilirubin,indirect bilirubin,serum IgA,serum IgG and IgA/ C3 ratio were lower in patients with nephrotic syndrome(all P < 0.05).Conclusions:1.First part: The non-invasive IgAN diagnostic model established by the urinary erythrocyte count,total protein,low density lipoprotein cholesterin,IgA/C3 ratio and serum IgG has certain accuracy and can be used for assisting the diagnosis of IgAN with clinical manifestations of nephrotic syndrome.2.Second part: The non-invasive IgAN diagnostic model established by the urinary erythrocyte count,serum creatinine and IgA/C3 ratio has certain accuracy and can be used for assisting the diagnosis of IgAN with clinical manifestations of nephrotic syndrome.