Evaluation of clinical and laboratory features of antiphospholipid syndrome: a retrospective study of 637 patients.

We retrospectively analysed the data of 1519 antiphospholipid antibody (APLA) positive patients between 1986 and 1999. Among them 637 were considered to have antiphospholipid syndrome (APS) based on the 1999 preliminary classification criteria, while 704 patients had no clinical signs of the syndrome. Our aim was to compare the autoantibody profile and clinical characteristics of primary and secondary APS, moreover to evaluate the associations between different APLA and specific symptoms attributable to APS. In our results, the APLA profiles for primary and SLE-associated secondary APS were similar. Among the evaluated clinical symptoms, cerebrovascular thrombosis was found to be more frequent in the SLE-associated, than in the primary APS group (P = 0.04). We identified important differences in the clinical profile of patient populations with various types of APLA. Venous thrombosis occurred more frequently in subjects withlupus anticoagulant (LA), than in those with IgG or IgM type ACLA (P < 0.0001), while coronary, carotid and peripheral artery thrombosis occurred more often in subjects with IgG or IgM ACLA (P < 0.0001). These findings may support the role of antibodies to cardiolipin or its cofactor, beta2glycoprotein I (beta2-GPI) in the initiation and progression of atherosclerosis. Cerebrovascular thrombosis was detected in larger proportion of LA or IgG ACLA-positive patients compared with to IgM ACLA-positive subjects, while the occurrence of foetal loss was similar in all three groups.