Time to first recurrent thrombosis in adults with thrombotic antiphospholipid syndrome: a registry-based...

To estimate time to first recurrent thrombosis and to explore the association between recurrent thrombosis and clinical, laboratory/immunological, and treatment-related factors among Colombian adults with thrombotic antiphospholipid syndrome (APS) enrolled in the ARTMEDICA autoimmune diseases program (2013-2024).

We conducted a registry-based retrospective follow-up study of patients with thrombotic APS. Patients were followed from the index thrombotic event to the first recurrent arterial or venous thrombosis. Time-to-event analyses used interval-censored parametric survival regression with a log-logistic distribution. To explore factors associated with recurrence, we also applied a matched nested case-control design using conditional logistic regression.

We included 355 patients (mean follow-up 6.6 years), 71.0% female, median age 47 years (IQR 32-60). Primary APS accounted for 83.4% of cases, and the index event was arterial in 72.1%. During follow-up, 130 patients experienced a first thrombotic recurrence: 70.8% venous. The 10-year probability of first recurrence was 42% (95% CI 28.4-55.5%), with 20% (95% CI 10.5-29.1%) during the first 2 years. In the nested case-control, recurrent thrombosis was significantly associated with the LA + /aCL + /antiβ2GPI - profile (OR 4.8; p = 0.044), male sex (OR 1.8; p = 0.038), prior gestational death (OR 2.4; p = 0.008), and ANA positivity (OR 2.4; p = 0.015).

The risk of recurrent thrombosis was highest during the first 2 years after the index thrombotic event, supporting an early vulnerable phase and underscoring the need for closer clinical surveillance and secondary prevention. Limitations of the study include its retrospective design, the lack of standardized anticoagulation monitoring and residual confounding. Key Points • Thrombotic APS carries a high early recurrence burden despite anticoagulation, particularly during the first 2 years after the index event. • Early identification of high-risk patients and intensive surveillance may be critical to prevent recurrent thrombosis.