Evaluation of the Clinical Performance of a Novel Chemiluminescent Immunoassay for Detection of Anticardiolipin and Anti-Beta2-Glycoprotein 1 Antibodies in the Diagnosis of Antiphospholipid Syndrome

Detection of antiphospholipid antibodies represents the first-line approach for diagnosis of antiphospholipid syndrome (APS). In this study, we evaluated the clinical performance of a novel chemiluminescence assay (CIA) in detection of IgG/IgM/IgA anti-cardiolipin (aCL) and IgG/IgM/IgA anti-β2 glycoprotein 1 (aβ2GP1) antibodies and to compare it with commercial enzyme-linked immunosorbent assay (ELISA) kits from the same manufacturer. A total of 227 sera were tested in this study, including 84 samples from patients with APS, 104 samples from patients with non-APS diseases as disease controls, and 39 healthy controls. Serum IgG/IgM/IgA aCL and IgG/IgM/IgA aβ2GP1 were determined by both ELISA (QUANTA Lite™ ELISA) and CIA (QUANTA Flash®assays). Significant quantitative correlations were identified between ELISA and CIA in IgG/IgM/IgA aCL and IgG/IgM/IgA aβ2GP1 autoantibodies detection (P < 0.001), with the rho value ranging from 0.51 to 0.87. In addition, ELISA and CIA demonstrated good qualitative agreements in IgG/IgM/IgA aCL and IgM/IgA aβ2GP1 autoantibodies determination with kappa coefficient ranged from 0.52 to 0.77. In contrast, ELISA and CIA showed a moderate qualitative agreement in IgG aβ2GP1 detection with a kappa value of 0.2. Notably, significantly higher IgG aβ2GP1 positive sera were detected by CIA, compared to those detected by ELISA in both primary APS (52.9% vs. 8.8%) and APS associated to other diseases sera (70.0% vs. 8.0%). For diagnosis of APS, IgG aβ2GP1 detection by CIA (IgG aβ2GP1 CIA) demonstrated the highest sensitivity (63.1%), followed by IgG aCL CIA (48.8%). More importantly, IgG aβ2GP1 CIA demonstrated the highest ability to predict the thrombotic events in patients with APS, with an OR of 3 (95% CI: 1.1–7.9). Our data suggest that this novel CIA assay had good performance in detecting aCL and aβ2GP1 antibodies, especially in the detection of IgG aβ2GP1 antibodies. Our findings could shed insight on the application of CIA in the laboratory diagnosis of APS in China.