The Cutoff Value and Prognosis of Anti-PLA2R for Idiopathic Membranous Nephropathy: A Single- Center Retrospective Study From China

Background: ： Analyzing the antibody level of anti-phospholipase A2 receptor (anti-PLA2R) with idiopathic membrane nephropathy (IMN) and its correlation with clinical parameters and prognosis, and to explore optimal cut-off value for Chinese patients. Methods: All hospitalized patients with renal biopsy from April 2017 to November 2019 in Peking University Third Hospital whose clinical and pathological characteristics were analyzed, and the level of serum PLA2R antibodies was detected using the method of enzyme-linked immunosorbent assay (ELISA). Result: The sensitivity, specificity, and Youden index of anti-PLA2R in the diagnosis of IMN in the Chinese patients were 85.7%, 88.3%, and 0.740 for the 2.5 RU/ml cut-off value; 77.8%, 96.0%, and 0.737 for the 6.3RU/ml cutoff value, respectively. The area under the ROC curve was 0.916. Compared with the high titer group, the low titer group had a higher serum albumin level (p=0.016), a lower cholesterol level (p=0.025) and a lower low density lipoprotein cholesterol (p=0.010). Multivariable Cox regression analysis showed that just immunosuppressive therapy (adjusted HR=4.656, 95 % CI 1.461-14.839, p=0.006) was associated with higher remission rate of IMN patients. Conclusion: The best cutoff for ELISA method to detect anti-PLA2R antibodies in IMN patients is probably much lower (around 2-7 RU/ml) than that indicated by the manufacturer. The cut-off value of 6.3 RU/ml could get a higher sensitivity and not a lower specificity. If the IMN patients were treated actively, they maybe can get better prognosis.