Performance of two new, automated chemiluminescence assay panels for anticardiolipin and anti-beta2-glycoprotein I antibodies in the laboratory diagnosis of the antiphospholipid syndrome.

Introduction: Anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies are two of the three laboratory criteria for antiphospholipid syndrome (APS). All assays for antiphospholipid antibodies (aPL), coagulation assays as well as ELISAs, show methodological shortcomings, which makes the search for better assays everlasting. The purpose of this study was to investigate the diagnostic performance of two new, fully automated systems (Zenit RA and HemosIL Acustar) applying chemiluminescent technology for aPL detection.

Methods: The study cohort consisted of a patient population presenting with thrombosis. In such patient population, the demonstration of aPL determines whether a patient has APS or not with implications for treatment. One hundred and twenty-four patients with thrombotic complications, of whom 26 were patients with definite APS, were integrated in this study. Besides, aPL titres were compared to the Sapporo standards.

Results: Results of both systems agreed well with ELISA and mutually. Analysis of the discrepant results between Zenit and Acustar finally led to one misclassification as APS.

Conclusion: Diagnostic performances of both Zenit RA and HemosIL Acustar were comparable with odds ratios lower limits of CI of 5 for aβ2 GPI IgG for Zenit and Acustar and 6 and 5 for aCl IgG on Zenit and Acustar, respectively. However, even with these new automated systems, titres differed largely between systems, especially for aβ2 GPI IgG.