Comparative treatment-related adverse event cost burden in immune thrombocytopenic purpura

Real-world evidence on the safety profile and costs associated with immune thrombocytopenic purpura (ITP) treatment in adults is lacking. This study quantifies and compares adverse event (AE) crude rates and costs associated with ITP treatments as found in claims data.

A retrospective claims-based analysis was conducted using IMS Pharmetrics Plus database. Included patients were ≥18 years old, with a diagnosis of ITP (2007-2012); an ITP-related claim for anti-D, intravenous immunoglobulin (IVIG), rituximab, romiplostim, or eltrombopag; and 1-year continuous enrollment (3-years for rituximab) during follow-up. AEs and event costs were identified during active treatment, defined from the first claim of each drug to a pre-defined treatment gap or end of study period. Descriptive statistics were reported with Wilcoxon rank-sum significance tests.

A total of 2,518 patients were identified (mean age = 50.8 (±16.3 years); 55.8% male). Of all patients, 22.8% experienced any AE. Significantly fewer anti-D patients had any AE (13.8% vs IVIG: 21.1%, rituximab: 29.4%, romiplostim: 28.1%, eltrombopag: 22.4%). Nausea/vomiting and arthralgia/musculoskeletal pain were most common across treatments, and hemolytic events did not differ significantly across treatments. Most costly AEs were urinary tract infection, aseptic meningitis, and fever ($5000+/case); headache, nasal congestion, and hemolytic event were $4,000-5,000/case. Cost per AE did not differ by treatment.

Although lower than trial-based AE rates, claims for ITP treatment-related AEs are common, with higher numbers for rituximab and lower numbers for anti-D. This disparity suggests a possible differential cost burden overall that future analysis should explore.