Prevalence of Antiphospholipid Antibodies Negativisation in Patients with Antiphospholipid Syndrome: A Long-Term Follow-Up Multicentre Study.

Objective:  This article aims to analyse the rate of antiphospholipid antibodies (aPL) negativisation in patients with antiphospholipid syndrome (APS), and to evaluate potential new clinical manifestations after negativisation and/or aPL fluctuations in a long-term follow-up.

Methods:  Inclusion criteria are (1) any patients with an APS diagnosis according to the current Sydney criteria and (2) patients in whom aPL negativisation occurred. aPL negativisation was defined as repeated aPL measurements on at least two consecutive occasions at least 12 weeks apart, with a follow-up of at least 1 year since aPL first turned negative.

Results:  Out of 259 APS patients, a total of 23 patients (8.9%) met the inclusion criteria for persistent aPL negativisation. Patients were followed-up for 14.4 ± 8.1 years, experienced aPL negativisation after a mean of 5.3 ± 3.5 years and were followed-up after experiencing the aPL negativisation for a mean of 7.6 ± 5.8 years. Seventeen patients (73.9%) presented with thrombotic APS, 2 with pregnancy morbidity (8.7%) and 4 (17.4%) with both. Most of the patients (18; 78.3%) had a single aPL positivity, 5 (21.7%) double, while no triple aPL positivity was observed. At the time of data collection, after aPL negativisation, anticoagulation was stopped in 8 patients with previous thrombotic venous event (8/21, 38%) according to the treating physicians' judgements. None of the patients experienced any recurrent thrombotic event during the follow-up period after their aPL negativisation.

Conclusion:  In our patient cohort consisting of 259 patients with definitive APS, we observed over a mean observation period of > 5 years, that aPL negativisation occurred in approximately 9% of patients. Negativisation occurred most often in patients who were previously found to be positive for only one aPL.