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

Background Phosphatidylserine-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. Objectives To ascertain the value of aPS/PT for APS diagnosis. Methods We 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. Results The Initial study comprised 247 subjects.Statistically significant correlation in the IgG aPS/PT values was obtained with both ELISA kits (r=0.827, p Validation study (n=214) a statistically significant correlation was found in the IgG aPS/PT titers with both ELISAs (r=0.827, p Conclusions The performance of IgG aPS/PT using Inova and MBL ELISA kits is reliable. IgG aPS/PT detection is an easily performed laboratory parameter that may help in the diagnosis of APS. Acknowledgements The authors want to acknowledge the contributions of the late Prof. Silvia Pierangeli, University of Texas Medical Branch, Galveston, TX, USA Disclosure of Interest O. Amengual: None declared, R. Forastiero: None declared, M. Sugiura-Ogasawara: None declared, K. Otomo: None declared, O. Kenji: None declared, C. Favas: None declared, J. Delgado Alves: None declared, P. Žigon: None declared, A. Ambrožic: None declared, M. Tomsic: None declared, I. Ruiz Arruza: None declared, G. Ruiz Irastorza: None declared, M. Bertolaccini: None declared, G. Norman Employee of: Inova Diagnostics, Inc, San Diego, CA USA, Z. Shums: None declared, A. Jiro Employee of: Medical and Biological Laboratories, Co. Ltd, A. Murashima: None declared, A. Tebo: None declared, M. Gerosa: None declared, P. Meroni: None declared, I. Rodriguez-Pintό: None declared, R. Cervera: None declared, J. Swadzba: None declared, J. Musial: None declared, T. Atsumi Grant/research support from: Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Bristol-Myers Squibb Co., Astellas Pharma Inc., Daiichi Sankyo Co., Ltd. and Mitsubishi Tanabe Pharma Co., Speakers bureau: Astellas Pharma Inc. and Mitsubishi Tanabe Pharma Co.