Second-line treatments and outcomes for immune thrombocytopenia: A retrospective study with electronic health records

Abstract

Background: Second-line treatment for immune thrombocytopenia (ITP) is not well reported for patients treated in real-world clinical settings.

Objective: The purpose of this study was to compare outcomes of four second-line treatments for ITP.

Patients/methods: Included adult patients had at least two medical records containing ITP diagnoses and second-line eltrombopag, romiplostim, rituximab, or splenectomy. Date of treatment initiation or splenectomy was set as index date, between July 1, 2008, and March 31, 2017. Patients had first-line corticosteroid or intravenous immune globulin treatment and continuous database activity from 6 months before to 12 months after index. Patient characteristics, treatment patterns, platelet counts, bleeding-related episodes (BREs), and thrombotic events (TEs) were compared by second-line treatment cohort.

Results: The sample included 3332 patients (mean age, 60.5 years; 52.3% female): eltrombopag (5.8%), romiplostim (9.9%), rituximab (73.3%), and splenectomy (11.0%). Patients having splenectomy were younger, more likely female and commercially insured, and less likely to require a third line of treatment than medical regimen cohorts. Proportions of patients having treatment-free (≥180 days with no second-line index or rescue agent) periods varied significantly (P = .01) by regimen: 33% for eltrombopag, 23% for romiplostim, 26% for rituximab, and 17% for splenectomy. All regimens significantly improved platelet counts, while TE and BRE rates differed significantly (P = .03 and P = .01, respectively) when all treatment groups were compared.

Conclusions: Over an average 7-year follow-up, all second-line regimens improved platelet counts, but eltrombopag yielded the highest proportion of patients with completely treatment-free periods of at least 180 days.

Keywords: eltrombopag; rituximab; romiplostim; splenectomy; thrombocytopenia.

Figure 1

The second‐line of therapy (LOT2) index date was the date of the first prescription for medication (eltrombopag, rituximab, romiplostim) or splenectomy date, collectively referred to as LOT2 index therapy. Patient characteristics were described during the baseline period. Treatment patterns and outcomes were observed in the follow‐up period. ITP, immune thrombocytopenia; LOT, line of therapy

Figure 2

Patients were initially identified by diagnosis codes for immune thrombocytopenia (ITP), then by LOT2 regimens of interest (eltrombopag, rituximab, romiplostim) or splenectomy. Included patients also had requirements in age and continuous activity in the database, as well as evidence of at least a first line (LOT1) and second line (LOT2) of treatment. Patients were excluded by clinical trial enrollment, pregnancy, or missing demographic information or platelet count data

Figure 3

*Statistically significant trend within treatments, across years. Comparisons were not made between treatments. Wald chi‐square test in a logistic regression

Figure 4

Platelet counts at baseline were collected within ± 14 days of initiation of the LOT2 index treatment; all available platelet counts were obtained for at least 1 year of follow‐up. Patients with no platelet count data in either period were excluded from the analytic sample. ITP, immune thrombocytopenia; LOT, line of therapy; SD, standard deviation. *Baseline and 1‐year mean counts differed significantly (P < .001) across all treatments. Platelet counts compared between eltrombopag and romiplostim were not significantly different, at baseline (P = .47) or follow‐up (P = .07).