Anticardiolipin antibodies are an independent risk factor for first ischemic stroke. The Antiphospholipid Antibodies in Stroke Study (APASS) Group.

We evaluated 255 consecutive first ischemic stroke patients and 255 age-/sex-matched hospitalized nonstroke patients at 15 medical centers for anticardiolipin antibodies (aCL). Sera were obtained within 7 days of stroke onset (cases) or hospital admission (controls) and stored at -20 degrees C until the aCL level was determined at a central laboratory. Results were read as negative, low, moderate, or high positive based on standardized optical density values. We recorded clinical, laboratory, and radiologic data without knowledge of antibody status. A positive aCL level was present in 9.7% of stroke patients and 4.3% of controls. The odds ratio for stroke status, given aCL positivity, was 2.31 after adjustment for age, ethnicity, gender, hypertension, diabetes mellitus, coronary artery disease, and cigarette smoking. Thus the frequency of aCL is significantly increased in these patients with first ischemic stroke. Further, aCL appear to be an independent risk factor for stroke in these patients.