Real-world practice of obstetricians in respect of assays for antiphospholipid antibodies

Objective. The international classification criteria (CC) for definite antiphospholipid syndrome (APS) recommend confirmation of the sustained presence, for at least 12 weeks, of both lupus anticoagulant (LA), as determined by aPTT and RVVT, and anti beta 2glycoprotein I (beta 2GPI) or anticardiolipin (aCL) IgG and/or IgM. However, it remains unclear whether obstetricians comply with the aforementioned CC for the diagnosis of APS in daily clinical practice. We performed a nationwide survey to examine the attitudes of Japanese obstetricians toward the use of assays for antiphospholipid antibodies (aPLs). Methods. A questionnaire was sent to 2,700 obstetric facilities where maternity checkups are car-ried out. The types of assays conducted for aPLs, ascertainment of persistence of the antibodies for at least 12 weeks, and the cutoff points used for the assays were examined. Results. Of the facilities surveyed, 61.5% carried out the assay(s) only once. In regard to the type of assay performed, 97.1% carried out the assay for aCL IgG and/or beta 2GPI-dependent aCL, while 67.9% performed the LA-aPTT and/or LA-RVVT assay. Only 8.8% carried out assays for both LA. As for the cutoff points used, 98% of the facilities used lower cutoff points described in the manufacturers' manuals rather than the cutoff values recommended in the CC. Conclusion. Thus, only a limited number of facilities adhered precisely to the CC for the diagnosis of APS. Inappropriate treatment and unnecessary expense are potentially major concerns when facilities overdiagnose APS using lower cutoff points or without ascertaining the persistence of the antibodies for at least 12 weeks. On the other hand, some patients miss the opportunity to be treated for APS because of the absence of testing for LA.