Wolfe GI, Kaminski HJ, Aban IB, et al. Randomized Trial of Thymectomy in Myasthenia Gravis. N Engl J Med 2016; 375:511-522
Submitted by David R. Mayans, MD, News Science Editorial Board
A single-blind randomized trial (rather-blinded) of thymectomy was performed in 126 non-thymomatous adults with myasthenia gravis of less than 5 years duration and Myasthenia Gravis Foundation of America clinical classifications of II to IV. Thymectomy was performed within 1 month of randomization by median sternotomy. Both groups were placed on increasing prednisone immediately after randomization until there was minimal disease activity present. Once minimal manifestation of disease was achieved, prednisone was tapered. Intravenous immunoglobulin and plasma were allowed for exacerbations. Azathioprine or cyclosporine were allowed for refractory cases. Patients who underwent thymectomy demonstrated significantly lower (improved) Quantitative Myasthenia Gravis at 3 years. The time-weighted average prednisone dose was also significantly lower in the thymectomy group (alternate day dose of 44 mg vs 60 mg). There was no difference in treatment association complications (including death) between the groups. Fewer patients in the thymectomy group were hospitalized due to exacerbation than the prednisone alone group (9% vs 37%).
Although thymectomy has been performed for many years in patient with myasthenia gravis and assumed to be beneficial, it has been challenging to prove its efficacy. This study demonstrates a clear clinical benefit of thymectomy in patients with non-thymomatous myasthenia gravis. The relatively high prednisone doses at the conclusion of the study are due partially to restriction of steroid-sparing agents by the study protocol. An interesting modification of this study, therefore, might be a study of thymectomy compared to “maximum medical therapy” with the addition of an agent such as azathioprine, cyclosporine, or mycophenolate mofetil.
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