Clinical and Prognostic Significance of Non-criteria Antiphospholipid Antibody Tests

Abstract

Classification criteria for antiphospholipid syndrome (APS) require IgG and IgM isotypes of the anticardiolipin antibodies (aCL), anti-β2 glycoprotein I antibodies (aβ2GPI), and/or the lupus anticoagulant (LA) to satisfy the laboratory criterion for disease definition. However, over the past 20 years, several other non-criteria antiphospholipid antibodies (aPL) directed to other proteins of the coagulation cascade (i.e., prothrombin and/or phosphatidylserine–prothrombin complex), to some domains of β2GPI, or to the anticoagulant activity of annexin A5, have been proposed. The Laboratory Diagnostics Task Force at the 14th International Congress on aPL (Rio de Janeiro, Brazil, 2013) highlighted several non-criteria assays. However, there was consensus that further studies are necessary to obtain high-quality evidence defining their role as risk predictors. The task force reviewed the literature and conducted new studies between 2013 and 2016; the conclusions were presented at a special session during the 15th International Congress on aPL (www.apsistanbul2016.org, North Cyprus, September 2016). This paper updates our recommendations.