Extended Preoperative Immunotherapy Duration Reduces the Risk of Myasthenia Gravis Exacerbation for Patients with Thymoma: A Multicenter Retrospective Cohort Study

Patients with thymoma-associated myasthenia gravis (TAMG) frequently have a higher risk for clinical deterioration. Previous studies primarily focused on postoperative myasthenic crisis (MC), leaving intermediate and long-term MG outcomes after thymectomy largely unexplored. This study aimed to identify predictors of postoperative acute exacerbation within 1 year after thymectomy and explore the potential benefits of preoperative immunotherapies. This multicenter retrospective study enrolled 347 patients with TAMG from 1756 individuals between February 2008 and October 2024. The primary endpoint was defined as the occurrence of acute exacerbation within 1 year postoperatively. Statistical evaluation employed logistic regression, Cox proportional hazards models, receiver operating characteristic analysis, and Kaplan–Meier curves. Of the study cohort, 96 patients (27.7%) had postoperative acute exacerbation of MG within 1 year. Multivariate Cox regression analysis identified that preoperative Myasthenia Gravis Foundation of America (MGFA) III–V was an independent risk factor for postoperative acute exacerbation (hazard ratio, HR 3.913, P < 0.001); preoperative immunotherapy duration > 14 days was associated with a protective effect (HR 0.419, P < 0.001). Multivariate logistic regression analysis identified preoperative MGFA III–V (odds ratio, OR 0.392, P < 0.05), reduced rate of R0 resection (OR 0.440, P < 0.05), and postoperative acute exacerbation (OR 0.245, P < 0.001) as independent risk predictors for achieving minimal symptom expression (MSE) at 1 year postoperatively. A preoperative immunotherapy duration exceeding 14 days is crucial for improving postoperative outcomes for TAMG.