BACKGROUND: Guidance for antiphospholipid antibody (aPL) testing after unprovoked venous thromboembolism (VTE) is inconsistent. Real-world data on the prevalence and outcomes of antiphospholipid syndrome (APS) in those presenting with unprovoked VTE are limited. OBJECTIVES: To determine APS prevalence after unprovoked VTE, compare outcomes from universal versus selective aPL testing, and assess thrombosis recurrence in APS patients within a multi-centre UK cohort. METHODS: This retrospective analysis included 897 patients with unprovoked VTE from five UK centres. One centre used universal (n=533) and four used selective (n=364) aPL testing. The primary outcome was APS prevalence. Secondary outcomes included thrombosis-free survival by testing strategy and by anticoagulant (direct oral anticoagulant DOAC vs. vitamin K antagonist VKA) in APS patients. RESULTS: The overall APS prevalence was 11.7% and was higher in the universal testing compared to the selective cohort (15.8% vs. 5.8%). Baseline clinical features were poor predictors of APS. Among 105 APS patients (median follow-up 4.2 years), the annual thrombotic recurrence rate was 2.1 per 100 person-years. A non-significant trend towards higher recurrence was observed over time for DOACs vs. VKAs (3.8 vs. 1.3 events/100 person-years, p = 0.16). No thrombosis-free survival difference was found between testing strategies (p = 0.71). CONCLUSIONS: The prevalence of APS following unprovoked VTE is notable, and selective testing identified fewer APS cases in practice. Identifying aPL antibodies in patients with unprovoked VTE may inform discussions regarding anticoagulation duration and choice, although optimal testing strategies require further prospective evaluation.
Mathur et al. (Fri,) studied this question.