Prognostic predictors of remission in ocular myasthenia after thymectomy

Identifying prognostic predictors can assist in making clinical decisions. This study aimed to identify the potential predictors of remission in patients with ocular myasthenia gravis (OMG) after thymectomy.

OMG patients who had thymectomy between 2011 and 2017 were reviewed retrospectively. Clinical outcomes were assessed according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS). Kaplan-Meier analysis was used to estimate the cumulative probability of complete stable remission (CSR). Univariate and multivariable analyses with Cox proportional hazards regression were used to identify predictors of CSR.

Fifty-one patients (23 male, 28 female) with a median age at OMG onset of 40 (range, 5-79) years were eligible for inclusion. Patients with thymomatous OMG (n=9) had a statistically older median age at disease onset [61 (range, 32-78) vs. 33.5 (range, 5-79) years, P=0.001], shorter duration from disease onset to thymectomy [3 (range, 2-24) vs. 10 (range, 1-132) months, P=0.004], and a higher rate of postoperative complication (44.4% vs. 9.5%, P=0.025), compared with non-thymomatous OMG (n=42). The estimated cumulative probability of CSR in the whole cohort was 41.8% (95% CI, 28.6-58.2%) 5 years after surgery. Age at onset of 40 years or younger (P=0.00016), female sex (P=0.069), and thymic hyperplasia (P=0.0061) were potential predictors under univariate analysis. However, only age at onset of 40 years or younger (HR: 4.117, 95% CI, 1.177-14.399, P=0.027) remained significant after multivariable analysis.

CSR could be achieved in about 40% of OMG patients 5 years after thymectomy and is likely to be predicted by age at onset of 40 years or younger.