Antiphospholipid syndrome: frequency, main causes and risk factors of mortality.

The presence of antiphospholipid antibodies has been shown to be related to an increased risk of thrombotic events. In patients with definite antiphospholipid syndrome (APS), that is, those who have had thrombosis and at least two positive determinations of antiphospholipid antibodies, secondary thromboprophylaxis with long-term anticoagulation therapy results in a low rate of recurrent thrombotic events, ranging from 0.016 to 0.031 events per patient per year. Thrombotic complications are, however, the most common cause of death in APS. The mortality rate in a large European cohort of patients with APS during a 5-year study period was 5.3%, and up to 40% of the deaths in this cohort were attributed to severe thrombotic events such as myocardial infarction, stroke and pulmonary embolism. Catastrophic APS is an unusual form of the disease, being observed in less than 1% of reported cases of APS, which is associated with a much higher mortality rate than classical APS. The combined use of anticoagulation, corticosteroids, plasma exchange and intravenous immunoglobulin therapy could result in a dramatic reduction in mortality, by approximately 20%, in patients with catastrophic APS.