Cost-Effectiveness of Imatinib in Comparison with Bone Marrow Transplant in Chronic Phase (CP) Chronic Myeloid Leukaemia (CML) in China.
Authors: Shen Zhixiang , Huang Xiaojun , de Costa Samara Mendes , Chen Zi , Xu Xiaoping , Wang Qiang , Chen Jie 
Published: October 2019

Abstract
Abstract 2474
Poster Board II-451

Background
Imatinib is associated with significant long-term survival benefits in CP CML patients versus bone marrow transplantation (BMT). Despite the proven benefits of imatinib and its position in first line treatment of chronic CML in several countries, BMT remains a treatment option in first line treatment of CML China. This modelling study was designed to explore the cost-effectiveness of imatinib in the Chinese setting.

Methods
A model was built in Microsoft Excel, with quarterly time intervals for overall survival over a 2-year period due to the lack of longer term follow up cost data for BMT. Published survival curves for the Chinese population were not available for either imatinib or BMT; however survival data for both imatinib and BMT from previous published literature were found to be broadly consistent with those reported in an unpublished survival meta-analysis of imatinib and BMT in Chinese population. The overall survival curve for imatinib sourced from the IRIS study (Druker et al 2006) was reconstructed in order to populate the imatinib arm of the model, and transplantation survival curves from Hasford et al (ASH 2008) were used to populate the BMT arm in the model. It was assumed that all patients surviving in each cycle remained in remission. Costs were based on the Chinese payment system. Due to the lack of publicly available cost data in China, a retrospective analysis of patient billings was conducted in 3 top tier hospitals in China (2 in Shanghai and 1 in Beijing) using a paper-based data collection questionnaire, with a target of 60 patients in total. Costs included in the model were: average cost of transplantation (including pre-operative and post-operative care and the transplantation procedure, as well as donor costs), complications associated with BMT and imatinib, quarterly cost of imatinib to the patients, and average quarterly charges for tests and monitoring. Utilities used in the model were sourced from IRIS; the utility for imatinib patients in remission was 0.854. Due to lack of published utility values in BMT patients, it was assumed that transplantation patients in remission would experience the same utility as interferon plus low-dose cytarabine (0.71). The outcomes of the model were total costs of treatment, life years, quality adjusted life years (QALY). A discount rate of 5% was used for costs and 0% for outcomes (utilities and life-years).

Results
Based on a cohort of 500 patients in each arm, the use of imatinib in CP CML yielded 497 and 971 life years (424 and 829 QALYs) at 1 and 2 years for imatinib vs. 485 and 898 for BMT (345 and 637 QALYs). Incremental life years (QALYs) were 12 (80) and 73 (192) at 1 and 2 years comparing imatinib with BMT. Total costs for imatinib were 73,194,400 RMB and 143,380,400 RMB at 1 and 2 years vs. 134,789,745 RMB and 143,552,071 RMB for BMT. Therefore, the cost savings for imatinib vs. BMT were 61,595,345 RMB and 171,671 RMB at 1 and 2 years. Imatinib is a dominant strategy to BMT (i.e., lower cost and higher efficacy) at 1 and 2 years. The model results were most sensitive to varying costs of BMT and discounting rates.

Conclusion
The results of the model demonstrate that imatinib is associated with improved overall survival and lower costs compared with BMT for the first 2 years in treating CP CML patients in the Chinese setting. Imatinib should be the first line treatment in CP CML based on both clinical and economic evidence.

Disclosures:
No relevant conflicts of interest to declare.