Clinical performance of automated chemiluminescent methods for anticardiolipin and anti‐β2‐glycoprotein I antibodies detection in a large cohort of Chinese patients with antiphospholipid syndrome

Introduction To assess the clinical performance and correlations of automated chemiluminescence assay (CIA) and enzyme‐linked immunosorbent assay (ELISA) for detecting antiphospholipid (aPL) antibodies in the diagnosis of antiphospholipid syndrome (APS). Methods The study recruited 505 subjects, including 192 with APS, 193 with connective tissue diseases other than APS, and 120 healthy donors. We measured anticardiolipin (aCL) and anti‐β2‐glycoprotein I (anti‐β2GPI) antibodies IgG, IgM, and IgA in all the samples using both CIA and ELISA. Results Total agreement between the two methods ranged from 83.50% for anti‐β2GPI IgG antibodies to 92.76% for anti‐β2GPI IgM antibodies in all the groups. Anti‐β2GPI and aCL IgG assays showed the highest Spearman's rho coefficients (anti‐β2GPI IgG = 0.742, aCL IgG = 0.715). Anti‐β2GPI IgG CIA showed the highest sensitivity for diagnosis of APS at 80.21%, which was significantly higher than the sensitivity of anti‐β2GPI IgG ELISA (52.08%). For diagnosis of APS, anti‐β2GPI IgG CIA had the best discrimination power with the area under the curves (AUC) of 0.922, followed by aCL IgG CIA (AUC of 0.905). While the CIA AUC was slightly higher in all cases, the difference was not statistically significant. Conclusion CIA measurements had a good agreement and correlation with comparative ELISA assays. The CIA anti‐β2GPI IgG however was significantly more sensitive for APS diagnosis. The two assay methodologies showed comparable predictive powers and support the value of the CIA method for improved diagnosis and management of patients with APS.