To investigate the possible relationships between plasma homocysteine levels and thrombotic events in a select population of rheumatoid arthritis (RA) patients with or without antiphospholipid (aPL) antibody positivity.
168 female RA patients attending the Extra-articular Involvement RA Clinic of University of Genova and 72 female subjects matched for age and vascular diseases as controls were included in the study. 30 of the RA patients showed aPL antibody positivity and 138 aPL antibody negativity on the basis of the concomitant presence or absence of high concentrations of anticardiolipin (aCL) antibodies or the presence of lupus anticoagulant (LA). All subjects were evaluated for plasma homocysteine concentrations and for the occurrence of thrombotic events.
Twenty-five RA patients and 5 controls reported a history of thrombotic events. Eleven and 5 of RA patients were found to have been previously affected by venous or arterial thrombosis, respectively. Plasma levels of homocysteine in aPL antibody positive patients with thrombosis were found to be significantly higher than in aPL antibody positive RA patients without thrombosis (p < 0.001). When RA patients with thromboses were analyzed, a significant increase of plasma homocysteine levels was found in aPL antibody-positive RA patients versus aPL antibody-negative RA patients (p < 0.04) and versus related controls (p < 0.003).
The association observed between aPL antibody positivity and high levels of plasma homocysteine in RA patients may represent a possible risk factor for thrombotic events. Therefore, it is suggested that hyperhomocysteinemia might be involved in the vascular-related mortality observed in RA patients with a history of thrombosis.