OP0223 Significance of IGG Phosphatidylserine-Dependent Antiprothrombin Antibody Testing for the Diagnosis of Antiphospholipid Syndrome: Results from the Initial and Validation International Multi-Centre Studies

BackgroundPhosphatidylserine-dependent antiprothrombin antibodies (aPS/PT) are strongly correlated with lupus anticoagulant. A Task Force of scientists at the International Congress on Antiphospholipid Antibodies (APLA 2010) accepted that aPS/PT would potentially contribute for a better identification of antiphospholipid syndrome (APS). Accordingly,we carried out an Initial and a Validation retrospective, cross-sectional multi-centre study on aPS/PT.ObjectivesTo ascertain the value of aPS/PT for APS diagnosis.MethodsWe conducted an initial study involving 8 centres from 7 countries.Demographics and clinical/laboratory data were retrospectively collected.A sample from the subjects was prepared at each institution.Specimens were blinded and determination of IgG aPS/PT performed at Inova Diagnostics, Inc.USA (Inova) using ELISA kits from two manufacturers:Medical and Biological Laboratories Co Ltd, Japan (MBL) and Inova.After completing the initial study, a Validation study with a new sample of subjects (5 different centres from 5 countries) was carried out using the same methodology.ResultsThe Initial study comprised 247 subjects.Statistically significant correlation in the IgG aPS/PT values was obtained with both ELISA kits (r=0.827, p