Thymectomy may not predict sustained clinical outcomes in patients with myasthenia gravis
Austria: Recent data in the European Journal of Neurology suggest the long-term clinical response of myasthenia gravis (MG) patients after thymectomy is significantly lower than that suggested by the initial response rates.
The observation that none of the evaluated clinical factors was tied to a worse outcome supports the clinical practice of patient selection for thymectomy. After surgery, the relative decline of acetylcholine receptor antibody (AChR-Ab) appears to be a promising prognostic marker.
Fritz Zimprich, Department of Neurology, Medical University of Vienna, Vienna, Austria, and colleagues undertook this study to investigate short- and long-term outcomes following thymectomy in patients with acetylcholine receptor antibody-positive myasthenia gravis.
For this purpose, the researchers retrospectively analyzed the rates of clinical response (defined as minimal manifestation, pharmacological remission, or complete stable remission). During follow-up, the occurrence of relapses was recorded. Clinical factors associated with achieving an initial or sustained response were analyzed.
Key findings of the study include:
- Ninety-four patients with a median age of 33 years (interquartile range [IQR] = 22–51), 68% with nonthymomatous MG, and 32% with thymoma-associated MG were included. An initial clinical response was reached 72% (68/94).
- Neither sex, age at onset, thymus histology, delay to surgery after disease onset, surgical approach, corticosteroid treatment, nor clinical severity before thymectomy was significantly associated with achieving this endpoint.
- During long-term follow-up (median = 89.5 months, IQR = 46–189.5), only half of the patients with an initial response (34/68) had a sustained response without relapses.
- No clinical factors predicted whether the response would become sustained.
- In patients without immunosuppressive treatment before thymectomy (n = 24), a high AChR-Ab reduction rate after thymectomy was associated with a higher likelihood of achieving an initial response.
The sustained long-term clinical response of MG patients after thymectomy is significantly lower than the initial response rates would suggest. The observation that none of the evaluated clinical factors was associated with a worse outcome supports the current clinical practice of patient selection for thymectomy. The relative decline of AChR-Abs after surgery appears to be a promising prognostic marker.
Reference:
Rath J, Taborsky M, Moser B, Zulehner G, Weng R, Krenn M, Cetin H, Matilla JR, Müllauer L, Zimprich F. Short-term and sustained clinical response following thymectomy in patients with myasthenia gravis. Eur J Neurol. 2022 Apr 18. doi: 10.1111/ene.15362. Epub ahead of print. PMID: 35435305.
