Antiphospholipid antibodies and thrombosis: do test patterns identify the patients' risk?

We retrospectively analyzed the antiphospholipid profile of 103 lupus anticoagulant-positive patients to investigate whether laboratory patterns emerged for their association with arterial and venous thrombosis in the antiphospholipid syndrome. Anticardiolipin, anti-2-glycoprotein I and antiprothrombin antibodies were combined with coagulation tests in different patterns, which included from 2 to 5 laboratory variables. Overall, 22 out of 180 available associations reached significance: 14 with any type of thrombosis and eight with venous thrombosis. In all but two cases, anticardiolipin antibodies>40 units were present in the laboratory patterns that reached significance. Anti-2-glycoprotein I antibodies were present in 11 significant patterns, and antiprothrombin antibodies in seven cases. Increasing the number of variables of the laboratory patterns did not increase the odds ratio (OR) towards thrombosis. In conclusion, this analysis confirmed that the presence of IgG anticardiolipin antibodies at medium to high titres, either alone or in various combinations with other tests, is clinically useful to establish the patients' risk of thrombosis. The role of the other antiphospholipid antibodies is less clear.