Assessment of diagnostic methods for the detection of anticardiolipin and anti-βeta glycoprotein I antibodies in patients under routine evaluation for antiphospholipid syndrome.

Background: We assessed the performance characteristics and correlations of the traditional enzyme-linked immunosorbent assay (ELISA) and chemiluminescence immunoassay (CIA) for detecting IgG and IgM antibodies to cardiolipin (aCL) and beta glycoprotein (anti-βGPI) antibodies in patients under routine evaluation for APS.

Methods: Patients (n = 216) referred to ARUP Laboratories for lupus anticoagulant (LAC) and/or aCL or anti-βGPI IgG/IgM antibodies evaluation were assessed by ELISA and CIA methods. Diagnostic accuracies, correlations between methods and specific clinical manifestations in APS were investigated.

Results: The areas under the curve (%) for APS using LAC with CIA (74, 95% CI: 65-82) or ELISA (70, 95% CI: 61-79) aPLs were comparable. The overall agreements and linear regression correlations between methods for aPL antibody of the same specificity were variable: aCL IgG 87.3%; R = 0.7491, aCL IgM 71.6%; R = 0.2656, anti-βGPI IgG 77.2%; R = 0.7688 and anti-βGPI IgM 81.7%; R = 0.3305.

Conclusions: With inclusion of LAC, the ELISA and CIA show comparable performance for the diagnosis of APS. However, correlations of APS-specific manifestations were dependent on method of detecting the aPL antibodies suggesting platforms may not be used interchangeable.