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Thymectomy and disease duration in non-thymomatous acetylcholine receptor antibody-positive myasthenia gravis: a single-centre, cross-sectional study
  1. Hye Yoon Chung1,
  2. Seung Woo Kim1,
  3. Jin Gu Lee2,
  4. Hyo Sup Shim3,
  5. Ha Young Shin1
  1. 1 Department of Neurology, Yonsei University College of Medicine, Seoul, Korea (the Republic of)
  2. 2 Department of Thoracic and Cardiovascular surgery, Yonsei University College of Medicine, Seodaemun-gu, Korea (the Republic of)
  3. 3 Department of Pathology, Yonsei University College of Medicine, Seodaemun-gu, Korea (the Republic of)
  1. Correspondence to Dr Ha Young Shin, Department of Neurology, Yonsei University College of Medicine, Seodaemun-gu, Korea (the Republic of); hayshin{at}

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Myasthenia gravis (MG) is an autoantibody-mediated disorder of the neuromuscular junction. Autoantibody against the acetylcholine receptor (AChR-Ab) is detected in 80% of MG patients, and its production is associated with thymic follicular hyperplasia (TFH) and germinal centres in the thymus. In non-thymomatous AChR-Ab positive MG (AChR-MG), the therapeutic effect of thymectomy has been demonstrated.1 Although thymectomy is generally performed on patients with short disease duration, few studies have directly evaluated the impact of disease duration on the therapeutic effect of thymectomy. In addition, it is unclear whether thymectomy done after the early stage of MG is effective.2 We aimed to assess whether thymectomy during the early stage of MG has a better therapeutic effect than thymectomy done at a later stage in patients with non-thymomatous AChR-MG and whether thymectomy done at a later stage is more beneficial than medical treatment alone.


This single-centre, retrospective, cross-sectional study obtained data from medical records of patients with non-thymomatous AChR-MG. Among 1214 patients, those who had undergone thymectomy (thymectomy group) were propensity score matched with those who had not (control group) (online supplemental figure 1). Thymectomy was performed as a therapeutic option to potentially minimise or avoid immunotherapy, or if patients showed inadequate response to immunotherapy or could not maintain immunotherapy due to side effects. The thymectomy group was further divided into two groups according to disease duration before surgery: early-thymectomy group (less than 2 years of disease duration before thymectomy) and late-thymectomy group (2 or more …

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  • HSS and HYS are joint senior authors.

  • HSS and HYS contributed equally.

  • Contributors HYC drafted the manuscript and figures with input from SWK, JGL, HSS and HYS. HYC and HYS performed statistical analysis. HYC, SWK, JGL, HSS and HYS contributed to the acquisition and analysis of data. All authors critically revised, read and approved the final manuscript.

  • Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. NRF-2020R1C1C1010130).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.