The association of antibodies to cardiolipin, β2‐glycoprotein I, prothrombin, and oxidized low‐density lipoprotein with thrombosis in 292 patients with familial and sporadic systemic lupus erythematosus

Abstract

Objective: To determine the prevalence of antibodies to phospholipid‐binding plasma proteins (aPL) and to oxidized low‐density lipoprotein (OX‐LDL), and to study the association of these antibodies with thrombosis and coronary heart disease (CHD) in patients with systemic lupus erythematosus (SLE).Methods: Clinical data and sera from 89 Finnish patients with familial and 203 with sporadic SLE were available for the study. Enzyme‐linked immunosorbent assays (ELISA) were used for antibody determination.Results: The occurrence of thrombosis in our SLE patients was 13.7% (40/292) and of clinically diagnosed CHD was 1.4% (4/292). All antibody assays, except IgM‐aCL, were significantly associated with thrombosis. IgG‐aCL alone or in combination with anti β2‐GPI or with anti OX‐LDL were reasonably sensitive (38%, 48%, and 58%, respectively) and specific (87%, 80% and 72%, respectively) for a history of thrombosis. A high risk of arterial thrombosis (TIA or stroke) was associated with positivity of IgG‐aCL, anti β2‐GPI, and anti‐prothrombin. Venous thrombosis was significantly associated with all other assays except IgM‐aCL and anti‐prothrombin. No test correlated with CHD, but the number of affected patients was small. There were three multiplex SLE families with two patients having a history of thrombosis: no consistent pattern of aPL or anti OX‐LDL was found in these patients.Conclusion: IgG‐aCL alone or in combination with anti β2‐GPI or anti OX‐LDL are sensitive and specific tests for detecting SLE patients at increased risk of thrombosis. The aetiopathogenesis of thrombosis in familial SLE appears to be multifactorial.