Background/Purpose: Thrombocytopenia is a common feature of both systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) and in the former most frequently results from antiplatelet antibodies (i.e., AITP) or aPL antibodies. Patients with AITP paradoxically have an increased risk of thrombosis and it has been speculated that this can result from co-presence of aPL. Primary APS is associated with both thrombosis and thrombocytopenia. We assessed whether there was an association between a history of thrombocytopenia and the prevalence of a thrombotic event in a large, multiethnic cohort of SLE patients.

Methods: We analyzed the NYU SLE SAMPLE registry, consisting of patients fulfilling ACR and/or SLICC criteria for SLE. We identified 105 patients whose SLE criteria included the presence of one or more of the following aPL antibodies: lupus anticoagulant, IgG or IgM anti-β₂-glycoprotein-I, and/or IgG or IgM anticardiolipin antibodies; and determined whether these patients had thrombocytopenia (<100,000/μL) recorded among their SLE classification criteria. We reviewed each patient’s medical record to identify the prevalence of arterial or venous thrombosis (defined as DVT, PE, stroke, arterial occlusion with gangrene or amputation), and/or obstetric events. We compared the prevalence of thrombotic events in SLE patients with and without history of thrombocytopenia.

Results:

The NYU SLE SAMPLE currently includes 612 patients (90% female, mean age 43.0±0.9 years, and mean age of 41.0±0.3 years in the males); 54% of the subjects were Caucasian, 31% African American, 15% Asian, 30% Hispanic White, and 5% Hispanic Black: 17% had aPL antibodies, of whom 89% were female and 11% male (mean age 43.0±0.2 years, 56% Caucasian, 33% African American, and 11% Asian, 24% Hispanic white and 4% Hispanic Black). The total numbers of patients with thrombotic events were 45 (43%), with 5/21 (23%) in the SLE patients with aPL and prior history of thrombocytopenia and 40/84 (47%; p=0.042) in the patients without thrombocytopenia. The most common thrombotic event was DVT followed by stroke.

Conclusion:

The prevalence of aPL in the NYU SLE registry was 17%, and adverse thrombotic events were less common in the patients with prior history of thrombocytopenia (5/21, 23%) as compared to those without (40/84, 47%). This unexpected finding could be explained by protective benefit of anti-platelet antibodies when co-occur with aPL in SLE, or less thrombogenic aPL in SLE when there is concomitant thrombocytopenia. Additionally, our data suggest that there might be different consequences of aPL between primary APS patients and SLE patients with aPL.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/history-of-thrombocytopenia-is-associated-with-lower-prevalence-of-thrombotic-events-in-systemic-lupus-erythematosus-patients-with-antiphospholipid-antibodies/