To evaluate the clinical outcome after aPL (antiphospholipid antibodies) disappearance in primary APS patients.

From a cohort of 70 patients with primary APS, we selected patients with positive aPL determinations at onset and ≥2 subsequent negative aPL determinations during the last 5years. To corroborate the immunologic profile, we determined IgG/IgM aCL antibodies, IgG/IgM antiβ2GPl, anti-annexin A5 antibodies and lupus anticoagulant (LA). All patients continued treatment with oral anticoagulants. Clinical data and aPL determinations at onset/after disappearance were obtained.

descriptive statistics and Kaplan-Meier analysis.

We found 24 patients with persistently negative aPL, including the last immunologic profile, 17 females, 7 males, mean age 51.7, disease evolution 16.3years, mean of 4 aPL previous positive determinations. aCL was positive at onset in 87.5%, 29% had double aPL positivity at onset (aCL/LA). Deep venous thrombosis (DVT) and ischemic stroke in 33% and pulmonary embolism in 12.5% were the most frequent manifestations at onset. INR range: 2-3. Time with aPL positive 109.4±80.7months. After 60months of follow-up since aPL disappearance, 45.8% of patients presented thrombosis recurrence, DVT in 9 patients, ischemic stroke in 1, pulmonary artery hypertension in 1. Other non-thrombotic APS manifestations were chronic ulcers in lower extremities and severe thrombocytopenia.

This study suggest, that in primary APS, persistent negative aPL profile is not an indication to interrupt oral anticoagulant therapy. However, there is a subset of patients that remained asymptomatic. Other studies are necessary in order to elucidate this controversy.