Abstract
Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the appearance of antiphospholipid antibodies (aPLs) and clinical findings such as arterial and/or venous thrombosis and obstetric complications. As per the revised criteria of the International Classification Criteria for APS, the items required for testing of aPL include anti-cardiolipin antibodies (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI), lupus anticoagulant (LA) activity. Recent clinical studies suggest that direct oral anticoagulant (DOACs) therapy affects coagulation assays for determining LA activity. In the present study, we investigated the effects of DOAC type and plasma concentration on dilute Russell’s viper venom time (dRVVT), which is recommended as the first-line test for determining LA activity. We prepared DOAC-containing plasma so that the DOAC concentrations equivalent to the peek and trough values in the patient’s blood by adding each of the four types of DOAC to pooled plasma from healthy individuals. We performed LA activity determination on these samples using three types of commercially available dRVVT reagents. In measurements using LA test-Gradypore and LA reagent DRVVT, which are widely used in Japan, all cases of plasma containing various DOACs were determined to be LA false positive. On the other hand, the recently developed Coagpia LA reagent correctly determined that all plasma containing various DOACs were LA negative. The present suggested that patients who received DOAC therapy may be diagnosed as LA false-positive in the dRVVT-LA test depending on the measurement reagent used. Therefore, we recommend using Coagpia LA reagent to determine LA activity in patients treated with DOACs.
