2026-04-23 バッファロー大学（UB）
高額な新規薬剤（年間30万～50万ドル）に比べ、手術は一時的コストで長期的負担を軽減し、ステロイド使用量も減少、副作用リスクの低下にも寄与する。
2016年に有効性が証明された治療法について、経済面でも有用性が裏付けられ、医療介入の価値評価の重要性を示す結果となった。
＜関連情報＞
- https://www.buffalo.edu/news/releases/2026/04/Thymectomy-economical-in-myasthenia-gravis.html
- https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2847674
非胸腺腫性重症筋無力症の治療における胸腺摘出術の経済的評価 Economic Evaluation of Thymectomy for the Treatment of Nonthymomatous Myasthenia Gravis
Joseph Lord, MSc; Matthew Walton, MSc; Peter Murphy, PhD;et al
JAMA Network Open Published:April 13, 2026
DOI:10.1001/jamanetworkopen.2026.6612
Key Points
Question Is thymectomy a cost-effective treatment option for nonthymomatous myasthenia gravis (MG) in the UK National Health Service (NHS)?
Findings In this model-based economic evaluation, thymectomy plus prednisolone resulted in a lifetime incremental quality-adjusted life year gain of 0.52 and a cost saving of £13 014 per patient, dominating a strategy of prednisolone alone.
Meaning The findings of this study suggest that thymectomy is a highly cost-effective treatment option for patients with nonthymomatous MG in the UK NHS.
Abstract
Importance Myasthenia gravis (MG) is a chronic autoimmune disease that significantly impairs patients’ quality of life by causing fluctuating muscle weakness and fatigue. While pharmacological treatment with corticosteroids remains a cornerstone of treatment, long-term use is often associated with substantial adverse effects. Although thymectomy is an established and effective alternative and adjunct to pharmacological treatment, its long-term cost-effectiveness within the UK National Health Service (NHS) is unknown.
Objective To evaluate the cost-effectiveness of thymectomy in addition to prednisolone therapy compared with prednisolone therapy alone for patients with nonthymomatous MG.
Design, Setting, and Participants This economic evaluation used a Markov state-transition model to simulate the costs and health outcomes of patients with nonthymomatous MG. The patients’ baseline characteristics, disease progression, and treatment efficacy were derived from patient-level data from the Thymectomy Trial in Nonthymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy (MGTX) clinical trial. The model adopted a UK NHS and Personal Social Services perspective over a lifetime horizon. Data analysis was performed from June 2024 to October 2025.
Main Outcomes and Measures The primary outcomes were incremental costs and quality-adjusted life years (QALYs) discounted at 3.5% per annum and the incremental cost-effectiveness ratio (ICER). Extensive deterministic and probabilistic sensitivity analyses were conducted to assess the robustness of the findings to parameter uncertainty.
Results There were 126 participants in the MGTX trial, with a mean age of 35.08 years; 70.63% were female. In the base-case analysis, thymectomy plus prednisolone dominated prednisolone alone, yielding higher health gains (14.63 QALYs vs 14.11 QALYs) and lower lifetime costs (£181 716 vs £194 730). This generated an incremental gain of 0.52 QALYs and a cost saving of £13 014 per patient. The results were robust across a wide range of sensitivity analyses. Probabilistic analysis (1000 simulations) showed that thymectomy had a greater than 99% probability of being cost-effective at a willingness-to-pay threshold of £25 000 per QALY.
Conclusions and Relevance In this economic evaluation, thymectomy was found to be a highly cost-effective intervention for nonthymomatous MG in the UK and likely to be cost-saving relative to prednisolone alone. These findings support current clinical guidelines recommending thymectomy for eligible patients and establish it as the most relevant comparator in evaluations of future health technologies. More broadly, this study demonstrates the importance of high-quality randomized clinical trial evidence in enabling health technology assessment of surgical procedures.
