Treatment patterns and safety outcomes after splenectomy or thrombopoietin receptor agonists as second-line therapy for immune thrombocytopenia: Korean claims-based study

Background Splenectomy and thrombopoietin receptor agonists (TPO-RAs) are recommended second-line therapies for immune thrombocytopenia (ITP). Although guidelines recommend tailoring second-line treatments to patient characteristics, this approach is often unclear in real-world practice. Objectives We examined claims-based time to next treatment (TTNT) and safety outcomes after splenectomy or TPO-RA as a second-line therapy using nationally representative Korean claims data. Methods Patients diagnosed with ITP between 2002 and 2021 were included. From the eligible cohort, we identified patients whose index second-line treatment was splenectomy (group 1) or TPO-RA without prior splenectomy (group 2). Propensity score matching was performed between patients in both groups who had received corticosteroids as first-line treatment. Results After matching, 447 group 1 and 57 group 2 patients were analyzed. Subsequent treatment was administered to 82.3% and 61.4% of patients in groups 1 and 2, respectively. Median TTNTs were 5.80 and 3.03 months in groups 1 and 2, respectively. Estimated TTNT curves diverged after 24 months, with a longer TTNT observed in the TPO-RA group. Pneumococcal infections occurred in 3.1% of patients in group 1 and none in group 2. Venous thromboembolism (VTE) occurred in 10.5% and 15.7% of patients in groups 1 and 2, respectively. The observed time to VTE was shorter in group 2 than in group 1. Conclusion Patients treated with TPO-RAs as a second-line therapy were associated with a longer TTNT after 24 months, whereas VTE occurred earlier in the TPO-RA group. However, these findings should be interpreted with caution because of residual confounding.