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

The necessity and optimal duration of post-thymectomy immunoregulatory medication (IM) in myasthenia gravis (MG) remain unclear.

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.

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.

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.

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.

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.