Cost effectiveness of romiplostim for the treatment of chronic immune thrombocytopenia in Ireland

Abstract

Background: Romiplostim, a thrombopoietin receptor agonist (TPOra), is a second-line medical treatment option for adults with chronic immune thrombocytopenia (ITP). Clinical trials have shown that romiplostim increases platelet counts, while reducing the risk of bleeding and, in turn, the need for costly rescue medications.

Aims: The objective of this study was to assess the cost effectiveness of romiplostim in the treatment of adult ITP in Ireland, in comparison with eltrombopag and the medical standard of care (SoC).

Methods: A lifetime treatment-sequence cost-utility Markov model with embedded decision tree was developed from an Irish healthcare perspective to compare romiplostim with eltrombopag and SoC. The model was driven by platelet response (platelet count ≥50 × 10(9)/L), which determined effectiveness and progression along the treatment pathway, need for rescue therapy (e.g. intravenous immunoglobulin [IVIg] and steroids) and risk of bleeding. Probability of response, mean treatment duration, average time to initial response and utilities were derived from clinical trials and other published evidence. Treatment sequences and healthcare utilization practice were validated by Irish clinical experts. Costs were assessed in <euro> for 2011 and included drug acquisition costs and costs associated with monitoring patients and management of bleeding, as available from published Irish reimbursement lists and other relevant sources. Deterministic and probabilistic sensitivity analyses were conducted.

Results: Romiplostim treatment resulted in an average of 20.2 fewer administrations of rescue medication (IVIg or intravenous steroids) over a patient lifetime than eltrombopag, and 29.3 fewer rescue medication administrations than SoC. Romiplostim was dominant, with cost savings of <euro>13,258 and <euro>22,673 and gains of 0.76 and 1.17 quality-adjusted life-years (QALYs), compared with eltrombopag and SoC, respectively. Romiplostim remained cost effective throughout a variety of potential scenarios, including short-term TPOra treatment duration (1 year). One-way sensitivity analysis showed that the model was most sensitive to variation in the cost of IVIg and use of romiplostim and IVIg. Probabilistic sensitivity analysis showed that romiplostim was likely to be cost effective in over 90 % of cases compared with eltrombopag, and 96 % compared with SoC at a willingness-to-pay threshold of <euro>30,000 per QALY.

Conclusions: Use of romiplostim in the ITP treatment pathway, compared with eltrombopag or SoC, is likely to be cost effective in Ireland. Romiplostim improves clinical outcomes by increasing platelet counts, reducing bleeding events and the use of IVIg and steroids, resulting in both cost savings and additional QALYs when compared with current treatment practices.

Fig. 1

Model treatment pathways for adult immune thrombocytopenia (the proportions of patients represent patient treatment flow after the failure of the previous treatment based on the findings of a 2008 survey of 169 UK clinicians [16] updated and validated to match Irish practice [17]). SOC standard of care

Fig. 2

Markov model with embedded decision tree overview (health states [platelets ≥50 × 10⁹/L, platelets <50 × 10⁹/L, dead] evaluated in 4-week cycles). GI gastrointestinal, W&R watch and rescue, Tn current treatment, Tn + 1 next treatment in sequence

Fig. 3

Deterministic sensitivity analysis: a romiplostim vs. eltrombopag, b romiplostim vs. standard of care (incremental net benefit is based on the incremental QALYs multiplied by the willingness-to-pay threshold, minus incremental costs. The central vertical line represents the base-case net benefit). CI confidence interval, IV intravenous, IVIg intravenous immunoglobulin, OP outpatient

Fig. 4

Cost-effectiveness acceptability frontier for romiplostim, eltrombopag and standard of care. QALY quality-adjusted life-year