Effectiveness and safety of direct oral anticoagulants in patients with thrombotic antiphospholipid syndrome and venous thrombosis: A retrospective cohort study

BACKGROUND: Vitamin K antagonists (VKA) are the recommended treatment for thrombotic antiphospholipid syndrome (TAPS), but it remains uncertain whether direct oral anticoagulants (DOAC) could serve as an alternative to VKA in a subgroup of low-risk TAPS patients with venous thromboembolism (VTE). OBJECTIVES: To compare the incidence of thrombosis recurrence between DOACs and VKAs in TAPS patients with VTE as index event. METHODS: In this retrospective cohort study, we included adults with TAPS and index VTE treated with a DOAC or VKA between January 2013 and March 2023. Outcomes were recurrent thrombosis, defined as arterial thromboembolism (ATE) or VTE, and bleeding. Cox regression with time-varying covariates was applied, adjusted for age and sex and stratified by laboratory risk profile according to the 2023 ACR/EULAR criteria. RESULTS: We included 277 patients (mean follow-up 3.9 ± 2.8 years); 87% single positive. Recurrent thrombosis occurred in 26 patients (9.4%). The risk of the combined ATE/VTE outcome was higher in the DOAC group than in the VKA group, but not statistically significant (aHR 1.90, 95% CI 0.81-4.49). When analyzed separately, DOAC use was associated with more arterial events (1.34 vs. 0.51 per 100 person-years; HR = 3.72 95% CI 1.04-13.29). Major bleeding occurred in 4.0% of patients, with similar rates between treatments (aHR 0.67, 95% CI 0.34-1.31). CONCLUSION: In TAPS patients with index VTE, DOACs were associated with more arterial recurrences, with no significant difference in the combined ATE/VTE outcome. Interpretation is limited by few events and retrospective design.