Background/Purpose: We evaluated the features of our systemic lupus erythematosus (SLE) patients who presented with immune thrombocytopenia (ITP) and compared them to other SLE patients. In addition, we searched for the frequency of autoantibody positivity in our ITP series and evaluated ITP patients who developed SLE during follow-up.

Methods: Patients who were diagnosed with SLE at our university’s rheumatology department and those diagnosed with ITP at the hematology department were retrospectively evaluated. The clinical features, autoantibody profiles and outcome of the patients were recorded down. SLE was diagnosed according to revised ACR criteria. ITP was diagnosed according to American Society of Hematology (ASH) 2011 guidelines and a platelet count <100000/mm3 was a prerequisite. Antiplatelet antibodies were not routinely evaluated. SLE presenting with ITP was diagnosed when the clinical symptoms of SLE and autoantibody positivity did develop within the first year after the diagnosis of ITP.

Results: Twelve (6.7%) of the 280 SLE patients who were diagnosed within this time period presented with isolated ITP. The median time for the development of SLE in these patients was 3 years. Two SLE patients presented with thrombotic thrombocytopenic purpura (TTP) and one SLE patient had TTP during follow-up.When the features of 14 SLE patients who presented with ITP or TTP were compared to others, it was seen that the mean age (31.8±11.1 vs. 38.6±12.1, p=0.043) and anti-ds-DNA positivity (21.4% vs. 47.3%, p=0.05) were lower in this group; and these patients tended to have more active disease during pregnancy or had a higher probability of initially presenting with pregnancy (35.7% vs. 15.8%, p=0.067).Fortyone SLE patients (14.6%) had thrombocytopenia during any time of their disease. SLE patients with thrombocytopenia had more frequently initially active SLE (SLEDAI score >6) (70.7% vs 37.3%, p<0.001); fever (26.8% vs 14%, p=0.038); neurologic involvement (34.1% vs. 18.5%, p=0.022); renal involvement (45% vs 25%, p=0.009); low C3 level (61% vs 30.6%, p<0.001); also, the frequency of patients whose disease started with pregnancy or become aggravated with pregnancy were significantly higher (31.6% vs. 14.3%, p=0.009). There was no association between antiphospholipid antibodies (APS) and thrombocytopenia in SLE patients. Of 216 patients with ITP, ANA was positive in 18.5% (28/151), and anti-DNA was present in 1.6%  (2/121). None of the patients had findings of SLE or other autoimmune rheumatic diseases. After 2, 5, and 6 years of follow-up, however, 3 female patients developed SLE. APS antibodies were positive in 29.3% (24/82) of ITP patients in which they were available. Nevertheless, except one, all were IgM antibody positivity at low titers. None of the cases with positive APS antibodies had history of thrombosis or abortion.    

Conclusion: Some patients with ITP might develop SLE during follow-up. Onset of SLE with pregnancy, renal or neurologic involvement, and initially active disease are risk factors for the development of ITP in SLE patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-lupus-erythematosus-patients-presenting-with-immune-thrombocytopenia-and-the-association-between-two-diseases/