Background: Prolonged anticoagulation is the treatment of choice for patients with thrombosis and the antiphospholipid syndrome. However, there is still debate about the optimum intensity of anticoagulation.
Methods: The study included 66 patients with antiphospholipid syndrome (Sapporo criteria) and previous thrombosis. All were receiving oral anticoagulation to a target international normalized ratio of 3.5. Every patient was individually interviewed to recall major bleeding and thrombotic episodes during the previous 12 months.
Results: Patients were mainly women and white. The rate of major bleeding was 6 cases per 100 patient-years (95% confidence interval [CI] 1.6-15.0). The rate of intracranial bleed was 1.5 per 100 patient-years (95% CI, 0.04-8.4). None of the bleeding episodes was fatal. The rate of thrombotic recurrences was 9.1 cases per 100 patient-years (95% CI, 3.3-19.6). Most recurrences took place in the same vascular bed as the original thrombosis. Age, time receiving anticoagulant therapy, primary vs secondary antiphospholipid syndrome, positivity for anticardiolipin antibodies, positivity for lupus anticoagulant, previous arterial thrombosis, previous stroke, previous venous thrombosis, and previous thrombocytopenia were not predictive of bleeding events. However, the risk of thrombotic recurrences was independently higher in patients who were receiving anticoagulation for longer periods.
Conclusions: The risk of intracranial and fatal bleeding in patients with definite antiphospholipid syndrome and previous thrombosis treated with oral anticoagulation to a target international normalized ratio of 3.5 is similar than in groups of patients treated to lower target ratios. The risk of thrombotic recurrences, even during anticoagulation, was high. Most recurrences took place in the same territory as original thromboses.