Description of therapeutic strategies in severe systemic lupus erythematosus-associated immune thrombocytopenia: a retrospective cohort study of response and relapse.

Objectives: To describe the response and relapse of severe thrombocytopenia in patients with systemic lupus erythematosus (SLE) with different treatments.

Method: We performed a retrospective cohort study, which included SLE patients who were hospitalized for thrombocytopenia of less than 30,000/µL platelets, from January 2012 to December 2021. Demographic and clinical information was obtained from clinical records. Kaplan-Meier and logrank test were performed.

Results: Forty-seven patients, mostly women (83%) with a median age of 31 years, were included in the study. Eight patients (17%) relapsed within a median period of 35.7 weeks. Initial acute treatment with prednisone at 1 mg/kg/day was as effective as glucocorticoid pulses. However, induction treatment with cyclophosphamide (CYC) had the lowest remission rate (43%, p = 0.034). There was no significant difference in relapse-free survival (RFS) among the acute glucocorticoid treatments. CYC induction was associated with lower RFS compared to rituximab (RTX) (CYC 43.6 weeks vs. RTX 51.8 weeks, p = 0.040) or azathioprine (AZA) (CYC 43.6 weeks vs. AZA 51.2 weeks, p = 0.024). Administration of antimalarials was associated with longer RFS (51.6 weeks vs. 45.0 weeks, p = 0.021). Factors such as antiphospholipid syndrome, IgG anti-β2 glycoprotein I positivity, renal and additional hematologic SLE activity during follow-up significantly reduced RFS.

Conclusions: Despite similar response of acute glucocorticoid regimens, induction therapy with AZA or RTX resulted in a longer RFS compared to CYC. Adding an antimalarial also improved RFS. Our study provides evidence that may help develop better treatment strategies for severe thrombocytopenia in SLE patients. Key Points • Induction therapy with azathioprine or rituximab provided longer relapse-free survival in SLE thrombocytopenia compared with cyclophosphamide. • Antimalarial administration was associated with longer relapse-free survival in SLE thrombocytopenia. • Antiphospholipid syndrome, IgG anti-β2 glycoprotein I positivity, as well as renal and additional hematologic SLE activity during follow-up, decreased relapse-free survival.