| Objective:Membranous nephropathy(MN)is mainly divided into idiopathic MN(iMN)and secondary MN according the etiology.A part of iMN showed "full house" in immunofluorescence and/or electron dense deposits deposited in multisite but without definite etiology,which was called "full house" MN or atypical MN(aMN).It is unknown whether aMN is a single pathological type or a subset of iMN.This study compared the clinical heterogeneity of iMN and aMN patients in a single-center,and analyze the antibody level of phospholipase A2 receptor(PLA2R)in patients with MN to explore more suitable cut-off value for Chinese patients.Methods:Retrospective analysis was performed on iMN and aMN patients at Peking University People’s Hospital from January 2006 to December 2015,detected the level of serum PLA2R antibody of them,multiple logistic regression analysis was used to compared the clinical and pathological characteristics of iMN and aMN,COX risk proportion model was used to contrast the renal outcomes between iMN and aMN patients.We detected the anti-PLA2R antibody level of all hospitalized patients during January 2018 to August 2018 by enzyme linked immunosorbent assay.According to the primary disease,patients were divided into MN group(including patients with iMN and aMN)and control group(other pathological types),compared the difference of anti-PLA2R antibody level between them,and the optimal cut-off value of MN was analyzed by ROC curve.Results:A total of 577 patients were enrolled in this study,including 278 in iMN group and 299 in aMN group.Compared with iMN patients,aMN patients characterized by younger onset age(47.1±16.2 vs 54.8±13.0 years old,p<0.001),more nephrotic syndrome accompanyed with nephritis syndrome in clinical manifestation(17.1%vs 6.1%,p<0.001),lower levels of C4(0.30±0.18 vs 0.27±0.09 g/L,p=0.016),more patients with pathologic phase III of MN(13.4%vs 2.5%,p<0.001),immune fluorescence intensity were stronger than iMN patients except IgG4.aMN patients had similar renal outcome compared with iMN patients(HR=0.787,95%CI 0.410～1.512,p=0.472)after demographics,baseline laboratory values and remission status at 6th month were adjusted.However,the complete remission rate of aMN patients was significantly lower than that of iMN patients(46.1%vs 58.2%,p=0.029),and aMN patients were more difficult to get complete remission using GC+CTX therapy(OR=0.480,95%CI 0.253 to 0.908,p=0.024)compared with iMN patients after multivariate adjusted.A total of 354 patients were enrolled in the anti-PLA2R antibody cut-off study,including 114 in MN group and 240 in control group from our center during January 2018 to August 2018.The serum anti-PLA2R antibody level in MN group was significantly higher than that in control group[16.87(1.88,57,26)vs 1.43(1.20,1.62)RU/ml,p<0.001].ROC curve analysis showed that the sensitivity,specificity and area under the curve were 69.3%(95%CI 60.3%～77.0%),92.9%(95%CI 89.0%～95.5%),and 0.859(95%CI 0.813～0.905)respectively to distinguish MN from other pathological types when the cut-off value was 2.28 RU/ml,which were significantly better than the cut-off value of 20.00RU/ml(sensitivity 46.5%,specificity 97.5%)and 14.00RU/ml(sensitivity 53.5%,specificity 97.1%).Conclusion:Our results suggested that aMN could be a subset of iMN,rather than a new pathological entity,but it had some special feature compared with iMN:younger,more nephritis syndrome,lower C4 levels,severer histological manifestation and lower complete remission rate.Reducing the cut-off value of anti-PLA2R antibody to 2.28RU/ml could improve its sensitivity without sacrificing specificity in distinguishing iMN or aMN from other pathological types. |
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