Persistency of low levels of anticardiolipin and anti-beta2 glycoprotein1 in thrombosis.

Background: Antiphospholipid antibodies, the hallmark of the antiphospholipid syndrome, are associated with both venous and arterial thrombosis. Despite some reports stating that this association may be present in patients with low titres of anticardiolipin antibodies, a clear association has only been established in the presence of a moderate to high concentrations (above 40 GPL or MPL).
Methods: In order to study whether low antibody titres could be associated with thrombosis, we reviewed the files of 196 patients, 94 with and 102 without thrombotic events, for a period of 4.4 and 5.1 years respectively. Files from patients with persistent low titres of antiphospholipid antibodies recorded in the unit database were selected, independently of the associated clinical history or diagnosis. Epidemiology, clinical and treatment information were collected and the serum variability of the antibody titres was analysed in relation to the presence of thrombotic events.
Results: Thrombotic events were classified as venous 81.9% and arterial 18.1%. 23/94 (24.5%) patients with thrombosis had miscarriages. There were no significant differences between serum concentrations of antiphospholipid antibodies in the thrombotic and non-thrombotic groups. However, there was a higher consistency of the antibody concentrations in patients with thrombosis, as seen by the significantly lower variability of IgG aCL and abeta2GP1 titres in patients with thrombosis when compared to non-thrombotic controls (p=0.0025 and p<0.0001, respectively).
Conclusion: Consistency of low titres of antiphospholipid antibody levels may be associated with a higher risk of thrombotic events overall.
(Copyright 2009 Elsevier B.V. All rights reserved.)