Confirmation of initial antiphospholipid antibody positivity depends on the antiphospholipid antibody profile

Abstract

Background: The revised classification criteria for the antiphospholipid syndrome state that antiphospholipid (aPL) antibodies (lupus anticoagulant [LAC] and/or anticardiolipin [aCL] and/or anti-β2-glycoprotein I [aβ2GPI] antibodies) should be detected on two or more occasions at least 12 weeks apart. Consequently, classification of patient risk and adequacy of treatment may be deferred by 3 months. Objectives: In order to early classify patient risk, we evaluated whether aPL positivity confirmation is related to aPL antibody profiles. Patients and Methods: Consecutive patients referred to our center who were initially positive in one or more tests exploring the presence of aPL were tested after 3 months. During a 4-year period, 225 patients were initially positive in one or more tests, and 161 were available for confirmation after 3 months. Patients were classified as triple-positive (n = 54: LAC+, aCL+, aβ2GPI+, same isotype), double-positive (n = 50: LAC-, aCL+, aβ2GPI+, same isotype) and single-positive (n = 53: LAC or aCL or aβ2GPI antibodies as the sole positive test). Results: Among subjects with triple positivity at initial testing, 98% (53 of 54) had their aPL profile confirmed after 12 weeks. The double-positive and single-positive groups had data confirmed in 42 of 50 (84%) and 23 of 57 (40%) subjects, respectively. Conclusions: Our results show that high-risk subjects with triple-positive aPL profiles are identified early, at the time of the initial screening tests. © 2013 International Society on Thrombosis and Haemostasis.