**3.4 Antiphospholipid syndrome**

Primary prophylaxis with anticoagulant medication has not been shown to be beneficial for asymptomatic patients with no other risk factors, regardless of risk profile. Instead, some authors suggest daily administration of a low dose of aspirin, but this measure is not widely accepted. If other risk factors for thrombosis are associated, such as hospitalization, surgery, or concomitant autoimmune disease, prophylaxis is recommended, on a case-by-case basis [16, 34].

Secondary prophylaxis is recommended for patients with definite antiphospholipid syndrome and consists of lifelong vitamin K antagonist medication with a target INR of 2–3. In case of relapse or episodes of arterial thrombosis, the target INR should be >3. Combination with aspirin is not supported by data and is subject to controversy [16, 35].

The use of DOAC in patients with the definite antiphospholipid syndrome is not recommended, following the results of several studies that found direct oral anticoagulation to have a lower efficacy and safety profile than traditional vitamin K antagonist therapy [36].
