Thymectomy with or without maintenance therapy for myasthenia gravis patients: a tri-center, real-world study

Background: The necessity and optimal duration of post-thymectomy immunoregulatory medication (IM) in myasthenia gravis (MG) remain unclear. Objectives: This study aimed to evaluate whether IM is required after thymectomy in MG patients and to determine the appropriate duration of IM in patients without postoperative deterioration by comparing long-term clinical outcomes. Design: This triple-center, retrospective study included 1248 MG patients who underwent thymectomy. Among these patients, we compared outcomes between 483 patients without post-thymectomy IM and 765 patients receiving IM. Methods: Efficacy outcomes included post-thymectomy deterioration and minimal manifestation status (MMS) at 1 year. Safety outcomes, tumor growth, and serious complications were assessed between groups. Subgroup analyses were performed in mild cases (Myasthenia Gravis Foundation of America clinical classification (MGFA) ⩽2a at discharge), patients receiving IM for >1 year, and patients receiving IM for >2 years. Propensity score matching (PSM) was conducted for validation. Results: Relative to 438 MG patients underwent thymectomy with no-IM therapy, 756 thymectomized MG patients receiving concomitant IM showed significantly superior outcomes, including lower deterioration (hazard ratio (HR) = 0.44, adjusted p < 0.001), lower deteriorated MGFA class (adjusted coefficient = 0.94, p < 0.001), and higher odds of achieving MMS at 1 year (odds ratio = 2.06, adjusted p < 0.001). No significant differences were observed in tumor development (3 years: p = 0.78; 5 years: p = 0.27) or serious complications ( p = 0.53). Similar trends were observed across subgroups. Among patients without postoperative deterioration, IM longer than 1 year reduced deterioration risk compared with ⩽1 year (HR = 0.67 (0.50–0.91), p = 0.01), whereas extending IM beyond 2 years offered no additional benefit ( p = 0.137). PSM analysis confirmed these findings. Conclusion: Our real-world analysis of 1248 MG patients suggests that thymectomy alone is not sufficient to achieve satisfactory outcomes. Post-thymectomy IM is recommended for at least 1 year, while extending treatment beyond 2 years appears to offer no further advantage in patients without deterioration.