A Single-center Retrospective Study Of Serum Anti-PLA2R Antibodies With Clinically Significant Cut-off Value In Adults With Idiopathic Membranous Nephropathy

Objective:To explore the most clinically significant cut-off value of serum anti-PLA2 R antibody(sPLA2R-Ab)in adult idiopathic membranous nephropathy(IMN),and analyze the correlation and influencing factors between sPLA2R-Ab level and each index.Methods:A total of 285 patients who received renal puncture biopsy and sPLA2R-Ab test from January 2018 to December 2021 were included in the Department of Nephrology,the First Central Hospital of Baoding City.Renal puncture biopsy is the gold standard for the diagnosis of IMN.According to the pathological results of renal puncture biopsy,it is divided into IMN group and control group(including all pathological types except IMN).Gender,age,systolic blood pressure(SBP),diastolic blood pressure(DBP),hemoglobin(Hb),24 h urinary protein(24h UP),blood urea nitrogen(BUN),serum creatinine(Scr),total protein(TP),albumin(ALB),total cholesterol(TC),triglyceride(TG),pathological results of renal puncture biopsy,and sPLA2R-Ab levels of all the participants were retrospectively collected.T test was used to compare the data conforming to normal distribution between groups.Non-parametric test was used to compare the skewness data between groups.The rate was compared by chi-square test.Spearman correlation analysis was used to analyze the correlation between sPLA2R-Ab level and various indexes in IMN patients.Logistic regression was used to identify risk factors for IMN.ROC curve was drawn to analyze the diagnostic value of sPLA2R-Ab for IMN,and the optimal critical value of sPLA2R-Ab for diagnosing IMN was obtained by calculating Yoden index..Results:1.Comparison of sPLA2R-Ab levels between IMN group and control groupsPLA2R-Ab level in IMN group was significantly higher than that in control group [23.85(4.13,74.10)RU/ml vs.1.21(0.66,2.07)RU/ml,P< 0.001].2.Comparison of clinical indexes between IMN group and control groupTP,ALB,BUN and Scr in IMN group were significantly lower than those in control group(P<0.05),TC and 24 h UP in IMN group were significantly higher than those in control group(P<0.05),and there was no difference in Hb and TG between the two groups(P>0.05).3.Intergroup comparison of different sPLA2R-Ab levels in IMN patientssPLA2R-Ab ≥20RU/ml group showed lower TP,ALB and higher TC(P < 0.05).In this study,there were no statistically significant differences in age,gender,SBP,DBP,Hb,BUN,Scr,TG and 24 h UP between the two groups(P > 0.05).4.Comparison of sPLA2R-Ab levels in IMN patients of different gendersThere was no difference in sPLA2R-Ab level between genders of IMN patients(P> 0.05).5.Correlation between sPLA2R-Ab in IMN group and each indexSpearman correlation analysis showed that: sPLA2R-Ab in IMN group was negatively correlated with TP and ALB(r=-0.385,-0.316,P<0.001),and positively correlated with Scr,TC and 24 h UP(r=0.170,0.227,0.176,P<0.05).In this study,sPLA2R-Ab was not correlated with age,sex,SBP,DBP,Hb,BUN and TG(r=-0.067,-0.128,0.087,0.079,-0.071,0.102,0.095,P>0.05).6.Logistic regression analysis was used to identify the risk factors for IMNAll possible factors influencing IMN were included in univariate Logistic regression,and the results showed that sPLA2R-Ab(OR=1.029,95%CI1.016～1.041,P<0.001),age(OR=1.021,95%CI1.003～1.039,P=0.024),T P(OR=0.938,95%CI0.913～0.964,P<0.001),ALB(OR=0.930,95%CI 0.899～0.962,P<0.001),BUN(OR=0.742,95%CI 0.652～0.845,P<0.001),24 h UP(OR=1.921,95%CI 1.135～3.252,P=0.015)were the relevant factors to distinguish the incidence of IMN in patients.sPLA2R-Ab(OR=1.021,95%CI1.009～1.033,P=0.001),the higher the age(OR=1.034,95%CI 1.010～1.058,P=0.005),the lower the BUN(OR=0.700,95%CI 0.598～0.819,P< 0.001),the more inclined to be diagnosed as IMN.7.ROC curve analysisWhen sPLA2R-Ab diagnostic IMN cut-off value was set at 3.315RU/ml,Youden index was the highest(0.651),and the area under the curve(AUC)was 0.829(95%CI 0.776～0.882).The sensitivity and specificity of IMN were79.4% and 85.7% respectively,P< 0.001.Conclusions:1.In this study,3.315RU/ml is recommended as the most clinically significant threshold for distinguishing sPLA2R-Ab from IMN patients with other pathological types.This new threshold can improve the early diagnosis rate in patients with IMN.2.PLA2 R is a specific receptor for IMN,and the sPLA2R-Ab level in IMN group is significantly higher than that in other pathological types。3.sPLA2R-Ab is associated with the activity of IMN disease.The higher the level of sPLA2R-Ab and age,the lower the BUN,the more likely the diagnosis of IMN.