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Objectives Antiphospholipid syndrome (APS) presents with various clinical features; some patients exhibit progressive, refractory disease not meeting catastrophic APS (cAPS) criteria. This study describes new subcategory in APS patients - Terrible APS (TrAPS), characterized by recurrent thrombosis despite optimal anticoagulation, often requiring immunomodulation or surgery.Methods We analyzed 306 primary APS patients, excluding those with obstetric, non-criteria APS, or cAPS. TrAPS was defined by >2 breakthrough thrombotic events despite anticoagulation (without provocation or cardiovascular risk), or the need for >1 immunomodulatory or surgical intervention.Results Among 209 thrombotic primary APS patients, 27 (12.7%) met the TrAPS criteria. These patients showed higher rates of venous thrombosis, microvascular involvement, heart valve disease, thrombocytopenia, and triple-positive antiphospholipid antibodies. TrAPS was associated with increased mortality (18.5% vs. 5.1%) and anticoagulation resistance (81.4% with breakthrough events). Based on multivariate analysis we have identified four key predictors which formed the basis of the TrAPScore: severe thrombocytopenia (<50,000, 4 points), heart valve involvement (4 points), microvascular manifestations (3 points), and triple-positive serology (2 points). A TrAPScore >6 had positive predictive value (PPV) of 78-82.5%, while a score <4 had a negative predictive value (NPV) of 96.9% for TrAPS diagnosis.Conclusions We herein individualised a particularly refractory APS subcategory – Named TrAPS. TrAPScore incorporate severe thrombocytopenia, heart valve disease, microvascular manifestation and triple positive serology. TrAPS score >6 predicted a high likelihood of severe, refractory disease while effectively excluded TrAPS.