Antiphospholipid syndrome (APS) is a disorder of recurrent venous or arterial thrombosis, pregnancy losses, and thrombocytopenia. Recurrent thrombosis has particularly adverse effects on patients prognosis. The factors that influence recurrence and management techniques that prevent these events remain controversial. To add further insight regarding predisposing factors and the prevention of thrombotic recurrence, 61 well-characterized patients with APS were followed up for a median time of 77 months.

A retrospective cohort study was conducted in which the following factors were examined to determine their influence on thrombotic recurrence: primary vs secondary syndrome; the presence of hypertension, hyperlipidemia, diabetes, or smoking; patient age, sex, and race; pregnancy and oral contraceptives use; and treatment with warfarin sodium, warfarin plus aspirin, aspirin alone, prednisone, or no treatment.

There was no difference between patients with primary and secondary APS with respect to recurrent arterial (55% vs 38%, respectively) or recurrent venous (47% vs 50%, respectively) thrombotic events. In all patients with APS, white race (P = .02) was associated with recurrent arterial events. Venous thrombosis occurred during pregnancy or in the postpartum period in 16 (30%) of 53 women and in 8 women taking oral contraceptives. Recurrent arterial and venous thromboses were significantly decreased with prophylactic warfarin use when compared with prednisone use or no treatment. Recurrences were infrequent in patients with prothrombin ratios of 1.5 to 2.0.

Treatment with warfarin was most effective in preventing recurrent arterial and venous thrombosis. Pregnancy and the use of oral contraceptives or prednisone may also influence recurrence.