Background Antiphospholipid syndrome (APS) is an autoinmune disease characterized by the presence of antiphospholipid antibodies (aPL) and at least one clinical event (thrombosis and /or pregnancy morbidities). The titers of aPL can fluctuate and eventually become negative. This negativization, particularly if persistent, may be associated with a lower frequency of clinical events.
Objectives To describe the clinical and serological course of patients with thrombotic APS as well as the factors related with the aPL negativization
Methods We performed a retrospective study including patients attended at the Rheumatology clinic from a tertiary hospital in Northern Spain. We included 94 patients with thrombotic APS according to Sidney criteria of 2006. They were classified according to the serological evolution as persistently negative aPL, transiently positive, and persistently positive aPL according to previously established criteria.
Results After a mean follow-up of 145±56 months, 48.9% of patients presented a persistently negative serology, whereas in 12.8% it was transiently positive, and persistently positive in 38.3%. When analyzing potential factors related to the negativization (table 1), we found that patients with positive lupus anticoagulant tended to have a persistently negative serology during follow-up, but it did not reach statistical significance (OR 2.7; 95% CI 0.8–9.4; p=0.145). We found no association between traditional cardiovascular risk factors or previous treatments and the serological evolution.
Conclusions After a mean follow-up of 12 years, 49% of thrombotic APS patients presented a persistently negative serology. We found no significant association between immunological, traditional cardiovascular risk factors or previous treatments and the persistently negative serology.
Disclosure of Interest None declared