Purpose: The prevalence of antiphospholipid antibodies (APA) in patients with immune thrombocytopenic purpura (ITP) varies from 25 to 75% in the literature. The risk of thrombosis in this subgroup of patients is debated. In parallel, thrombocytopenia is present in 22 to 42% of patients with antiphospholipid syndrome (APS).
Patients and methods: The main study objective was to compare the profile at diagnosis of lupus anticoagulant (LA), anticardiolipin antibody (ACL) and anti-β(2)GP-I antibody between a cohort of 93 chronic ITP patients and a cohort of 27 primary APS patients. The secondary objectives were: to evaluate the risk of thrombosis in ITP patients depending on the presence of APA; to compare the profile of APA and to assess the occurrence of lupus in APS patients depending on the presence of thrombocytopenia.
Results: In ITP patients, the prevalence of APA was 25%; association of several different APA was less frequent than in APS patients; mean titles of ACL and anti-β(2)GP-I antibodies were comparable between the two cohorts; two spontaneous venous thromboses occurred in ITP patients, with no particular profile of APA (median follow-up: 36 months). Thrombocytopenia was present in 26% of APS patients; it was always moderate and asymptomatic, and sometimes intermittent; no particular profile of APA was associated to thrombocytopenia; only one thrombocytopenic patient developed a systemic lupus and no particular profile of APA could be found associated (median follow-up: 48 months).
Conclusion: ITP patients with APA have less frequently an association of different APA than APS patients do; their risk of thrombosis appears low.
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