Lupus Anticoagulant Testing for Diagnosis of Antiphospholipid Syndrome: A Perspective Informed by Local Practice

Assessment for the presence or absence of lupus anticoagulant (LA) represents a common investigation in hemostasis laboratories. In particular, LA represents one of the laboratory criteria for the diagnosis of definite antiphospholipid syndrome (APS). The other laboratory criteria are the solid phase assays (anticardiolipin (aCL) and anti-β2Glycoprotein I (aβ2GPI) antibodies of IgG and IgM isotypes). Current International Society on Thrombosis and Haemostasis (ISTH) guidance recommends testing LA by at least two tests based on different principles, with the activated partial thromboplastin time (aPTT) and dilute Russell viper venom time (dRVVT) being preferred. Additional assays may be used in addition, or instead of these assays in particular situations. For example, aPTT and dRVVT assays are very sensitive to the presence of various anticoagulants, and this may lead to false-positive identification of LA. This is particularly problematic in the age of the DOACs (direct oral anticoagulants), which are now the leading anticoagulants in use worldwide. We review recent literature on LA testing as well as our local practice to provide an update on this common test procedure. Our experience should be useful for laboratories struggling with LA interpretation for diagnosis or exclusion of APS.