Determinants of risk for venous and arterial thrombosis in primary antiphospholipid syndrome and in antiphospholipid syndrome with systemic lupus erythematosus

Objective. Antiphospholipid syndrome (APS) is characterized by thrombosis (venous and arterial) and pregnancy loss in conjunction with the lupus anticoagulant, IgG or IgM anticardiolipin, or IgG or IgM anti- β ₂-glycoprotein I. In most series, only a minority of patients with antiphospholipid antibodies develop a clinical manifestation. Methods. A cross-sectional study of consecutive patients in the Hopkins Lupus Center was performed. Interviews were done and records were reviewed for the following variables: gender, ethnicity, hypertension, triglycerides, cholesterol, smoking, diabetes mellitus, homocysteine, cancer, hepatitis C, hormone replacement therapy/oral contraceptives, hereditary thrombophilia, anticardiolipin antibodies IgG, IgM and IgA, and lupus anticoagulant (LAC). Our aim was to identify risk factors associated with thrombosis and pregnancy loss in patients with antiphospholipid antibodies. Results. A total of 122 patients (84% female, 74% Caucasian) were studied. Patients were divided into 3 groups: primary APS, APS associated with systemic lupus erythematosus, and patients with systemic lupus erythematosus (SLE) with antiphospholipid antibodies but no thrombosis or pregnancy loss. Venous thrombosis was associated with high triglycerides (p = 0.001), hereditary thrombophilia (p = 0.02), anticardiolipin antibodies IgG > 40 (p = 0.04), and LAC (p = 0.012). Hypertriglyceridemia was associated with a 6.4-fold increase, hereditary thrombophilia with a 7.3-fold increase, and anticardiolipin IgG > 40 GPL with a 2.8-fold increase in the risk of venous thrombosis. Arterial thrombosis was associated with hypertension (p = 0.008) and elevated homocysteine (p = 0.044). Hypertension was associated with a 2.4-fold increase in the risk of arterial thrombosis. No correlations were found for pregnancy loss. Conclusion. The frequency of thrombosis and pregnancy loss is greater in APS associated with SLE than in primary APS. Risk factors differ for venous and arterial thrombosis in APS. Treatment of hypertension may be the most important intervention to reduce arterial thrombosis. Elevated triglycerides are a major associate of venous thrombosis, but the benefit of treatment is not known. Hereditary thrombophilia is an associate of venous but not arterial thrombosis, making it cost-effective to investigate only in venous thrombosis. The Journal of Rheumatology