Background: Many studies have concluded that the presence of anticardiolipin antibodies is associated with both venous and arterial thrombotic events. The role of IgA anticardiolipin has been studied previously with conflicting results. Some of this disparity is thought to be due in part to the lack of international standards in measuring these levels.

Objective : To further evaluate the role of IgA anticardiolipin anitbody as a risk factor for thrombosis.

Patients and Methods: We conducted a single institution retrospective review of all patients with elevated IgA anticardiolipin antibodies extracted from a database of 20,000 patients for whom IgA anticardiolipin had been measured.

Results: One hundred forty-eight patients were identified with elevated IgA anticardiolipin antibodies as measured by semiquantitative indirect Elisa. Patients had a median age of 52.5; 52% were African American, 38% Caucasain and 9% of other ethnic background. Of these patients, 67 had associated arterial or venous thrombotic events: 15.9% were pulmonary embolisms, 47.5% were deep venous thromboses and 36.6% were arterial thrombotic events. Patients were further evaluated for other thrombotic risk factors including IgG and IgM anticardiolipin antibodies; lupus anticoagulant; pt 20210; activated protein C resistance/Factor V Leiden; hyperhomocysteinemia; antithrombin; protein C/protein S deficiency; active malignancy with or without concurrent chemotherapy; tamoxifen, oral contraceptive or hormone replacement therapy; catheter-related risk; pregnancy; myeloproliferative disorders and hyperviscosity syndromes; sickle cell disease; and surgery, trauma or immobilization within 6 weeks of the event. In 35.8% of evaluated patients with elevated IgA and thrombotic events, there was was no concommitant elevation of IgG or IgM anticardiolipin. In 33.3% of patients with thrombotic events, none of the other predetermined risk factors were present.

Conclusion: IgA anticardiolipin may be an independent risk factor for development of venous and arterial thrombotic events. A large case-controlled or prospective, randomized trial with standardized measurement will likely be needed to further clarify this issue.

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