Antiphosphatidylserine/prothrombin antibodies define a high-risk antiphospholipid syndrome profile associated with organ damage

OBJECTIVES: Antiphosphatidylserine/prothrombin (aPS/PT) antibodies are promising non-criteria aPLs associated with antiphospholipid syndrome (APS) manifestations. Their influence on long-term outcomes and damage remains uncertain. To assess aPS/PT antibodies association with accrual damage and severe APS disease phenotypes, focusing on their potential for risk stratification. METHODS: This single-centre cohort study involved 163 patients who fulfilled the 2023 ACR/EULAR APS criteria. IgG/IgM aPS/PT, aCL, and anti-β2GPI antibodies were measured by commercial ELISA. Lupus anticoagulant (LA) was detected in accordance with the ISTH-SSC recommendation. Clinical data covered macrovascular, microvascular, obstetric, and hematologic manifestations. Damage was assessed using DIAPS. RESULTS: aPS/PT IgG and IgM were positive in 46.0 % and 65.6 %, respectively. aPS/PT IgG positivity was linked to microvascular involvement (58.7 % vs. 34.1 %, p=0.002), obstetric APS (57.4 % vs. 24.6 %, p