Ab0842 Line Immunoassay Versus Chemiluminescence Assay and Multiplexed Bead Immunoassay for Detection of Anti-Ro and Anti-La Antibodies

Background: Anti-Ro and anti-La antibodies are the hallmark of primary Sjögren's syndrome (pSS) and have long been included in the classification criteria for the disease[1]. Although various assays have been used for the detection of anti-Ro and anti-La antibodies, none have been recommended as the gold standard. Objectives: To compare the diagnostic performance of automated quantitative assays to that of line immunoassay (LIA), which is most commonly used in China. Methods: Based on the Chinese Sjögren's Syndrome Collaborative Research Group, this study recruited patients diagnosed with pSS (n=434) at 21 tertiary hospitals. The diagnostic performance of the chemiluminescence assay (CLIA) and multiplexed bead immunoassay (MBI) in detecting anti-Ro and anti-La antibodies was compared to that of LIA. Receiver operating characteristic analysis was performed to compare test accuracy between the different methods and areas under curves (AUCs) were calculated; the DeLong test was used to compare AUCs. Results: High specificity, varying from 95% to 100%, was observed by these assays in the detection of both anti-Ro and anti-La antibodies in patients with pSS (Table 1). Despite statistical difference in sensitivity, moderate to good qualitative agreement was achieved between assays, with kappa values ranging from 0.74 to 0.93. Notably, good diagnostic values were achieved by all of the assays (AUCs: 0.859 - 0.980); MBI yielded the best AUC values for anti-Ro60 and anti-La antibodies in pSS (Table 2). Conclusion: Automated quantitative assays, CLIA and MBI, are potential alternatives to LIA in the detection of anti-Ro and anti-La antibodies in patients with pSS. REFERENCES: [1] Shiboski CH, Shiboski SC, Seror R, et al. 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjogren's syndrome: A consensus and data-driven methodology involving three international patient cohorts. ANN RHEUM DIS 2017, 76(1):9-16. Acknowledgements: NIL. Disclosure of Interests: None declared.