Antiphosphatidylserine antibodies as diagnostic indicators of antiphospholipid syndrome

Background Antiphospholipid syndrome (APS) is an autoimmune condition that is diagnosed by the presence of at least one of the clinical manifestations (thrombosis and/or pregnancy failure) and one of antiphospholipid antibodies (aPL) laboratory tests. The most relevant aPL are lupus anticoagulant (LA), anti-beta2 glycoprotein I (aβ2GPI) and anticardiolipin (aCL). The clinical significance of other antibodies like anti-phosphatidylserine antibodies (aPS) is still under investigation. Objectives The aim of the study was to assess the diagnostic value of aPS antibodies, and to compare their utility to that of other aPL antibodies. Methods We conducted a prospective observational study consisting of 212 patients with suspected thrombosis, pregnancy failure, or unexplained, prolonged clotting time. Data on demography, clinical presentation and autoantibody levels were assessed. Descriptive analysis, accuracy analysis, sensitivity, specificity, predictive value and likelihood ratio were calculated for aPS in comparison to other aPL. Results The diagnostic value of aPS versus other aPL antibodies revealed the high specificity of aPS (87%), with 70% of aPS-positive patients being confirmed APS. When the aPS test was used as a single test, it was effective for detection of confirmed APS cases (p