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

BACKGROUND: The revised classification criteria for the antiphospholipid syndrome (APS) 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 patients risk and adequacy of treatment may be deferred by three months. OBJECTIVES: In order to early classify patients risk, we evaluated whether aPL positivity confirmation is related to aPL antibody profiles. PATIENTS AND METHODS: Consecutive patients referred to our Center initially positive to one or more tests exploring the presence of aPL were tested after 3 months. During a four-years period 225 patients were initially positive to one or more test 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% (53out of 54) had their aPL profile confirmed after 12 weeks. Double and single positivity 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 time of the initial screening tests.