Can Non-Thymomatous Late-Onset Myasthenia Gravis Benefit From Thymectomy? A Systematic Review and Meta-Analysis

Background: Thymectomy is beneficial for treating early-onset acetylcholine receptor antibody-positive myasthenia gravis (MG); however, its effects on late-onset MG (LOMG) remain less well understood. Given the increasing incidence of MG among the population 50 years old and above, addressing the question of whether thymectomy is effective for this age group is critically important. This study aimed to assess the present evidence for the efficacy of thymectomy in LOMG and identify potential characteristics that may predict the treatment response. Methods: Four electronic databases were searched from their inception to September 10, 2024. Six studies with both thymectomy and medical therapies in LOMG patients, along with another 14 studies with only a surgical group, were enrolled in the meta-analysis. The primary outcome was the response (remission and minimal manifestations status) to thymectomy in LOMG. Results: In LOMG, response in the surgical group was greater than in the medical therapies alone group (OR = 1.42 [0.86-2.35], p = 0.169), but not significantly. However, subgroup analysis showed that when the age of MG onset was >= 45 years old or the age at thymectomy was >= 50 years old, thymectomy appeared better than medical therapies alone (OR = 1.92 [1.06-3.48], p = 0.031). Across all 20 studies, 34% (24%-44%) of LOMG patients improved with thymectomy. A higher response was observed in patients with a preoperative duration of less than 3 years from diagnosis [39% (16%-65%), p < 0.001, q < 0.001]. Conclusion: Thymectomy may be a potentially effective treatment for LOMG, particularly in patients who undergo the procedure soon after diagnosis. A randomized controlled study for LOMG patients is needed.