Effectiveness and safety of primary thromboprophylaxis in antiphospholipid antibody carriers by serological 2023 ACR/EULAR domains.

INTRODUCTION

The 2023 ACR/EULAR antiphospholipid syndrome (APS) criteria reduced IgM weighting and introduced a category for isolated lupus anticoagulant (LA), creating uncertainty about primary thromboprophylaxis in aPL carriers with <3 laboratory points. This study evaluates efficacy and safety of antiplatelet therapy and predictive value of the new ACR/EULAR thrombotic risk profiles.

MATERIAL AND

METHODS

All asymptomatic carriers of single or confirmed LA, anticardiolipin (aCL), or anti-β2-glycoprotein I antibodies (anti-β2GPI), between January 2018 and March 2024 were included (n = 985). Primary outcomes were thrombotic-free survival (TFS), grade ≥3 bleeding-free survival (BFS), and bleeding symptoms. Logistic and Cox regression models were applied, and Altman-Andersen method estimated the number needed to treat (NNT) and harm (NNH).

RESULTS

During a median follow-up of 2.84 [IQR 1,12-4,74] years, venous (VTE) and arterial (ATE) thromboses occurred in 4.6% and 4.1% of patients, respectively. Among the entire cohort, aspirin (ASA) improved TFS (HR 0.51; p = 0.001) without affecting BFS (HR 0.96; p = 0.81). P2Y12 inhibitors were associated with higher ATE (OR 13.17; p < 0.001) and minor bleeding (OR 4.875; p = 0.007). High-risk venous profiles predicted VTE (OR 2.42; p = 0.005). Among 458 carriers with <3 laboratory points, ASA remained protective (HR 0.53; p = 0.047) without increasing minor or major bleeding. P2Y12 inhibitors showed no benefit in TFS and were linked to decreased BFS (HR 4.211; p = 0.008).

CONCLUSIONS

Low-dose aspirin may lower thrombotic risk without increasing bleeding in asymptomatic aPL carriers, even in those with <3 laboratory points. P2Y12 inhibitors demonstrated reduced efficacy and an increased risk of bleeding, warranting confirmation in future studies.