Characteristics of myasthenia gravis in elderly patients: a retrospective study

Background The incidence of myasthenia gravis (MG) is increasing, and its characteristics in elderly patients are believed to differ from those in younger patients. However, only a few studies have focused on elderly patients with MG. Objective To review the characteristics of MG in elderly patients and evaluate whether older age is an independent factor associated with achieving minimal manifestation status (MMS). Methods This retrospective cohort study included 367 patients (319 non-elderly and 48 elderly patients) with MG enrolled at Xiangya Hospital from September 1, 2016, to December 31, 2018. We collected demographic data and information regarding comorbidities, antibody status, Myasthenia Gravis Foundation of America classification, affected muscle groups, thymoma, and treatment. MMS was defined as the primary outcome. Results Comorbidities were more common in elderly than in younger patients with MG. Anti-acetylcholine receptor antibody was the dominant subtype, whereas anti-muscle-specific tyrosine kinase antibody was rare and detected only in non-elderly patients. Elderly patients were more likely than younger patients to have generalized MG, but the frequency of thymoma was lower (28.5% vs. 10.4%, p = 0.0078). MMS or better was achieved in 154 (48.3%) and 13 (27.1%) non-elderly and elderly patients, respectively. Older age did not appear to be an independent factor associated with MMS (hazard ratio = 0.625; 95% confidence interval, 0.345-1.131). Conclusions Older age was not an independent factor for a worse prognosis in patients with MG. The treatment of elderly patients with MG should be individually tailored.