Clinical differences of early and late-onset myasthenia gravis in 985 patients

Objective: The clinical differences of early-onset myasthenia gravis (EOMG) and late-onset MG (LOMG) have not been elucidated in China. In order to clarify this, a retrospective study was conducted in 985 MG patients, whose disease duration was longer than 3 years.

Methods: These patients were separated into EOMG and LOMG according to the onset age of 50 years. The clinical differences including demographics, clinical features, thymus abnormalities and comorbidities of EOMG and LOMG patients were analyzed.

Results: Results indicated that 485 were males and 500 were females, 714 were EOMG and 271 were LOMG. Female was more common in EOMG and male was more common in LOMG (p = 0.003). The peak onset age was 0–4 years in EOMG and 55–59 years in LOMG. Ocular MG (OMG) was more common in EOMG and generalized MG (GMG) was more common in LOMG (p = 0.004). The transformation rate of OMG to GMG was higher in LOMG (p = 0.002). The positive incidence of repetitive nerve stimulation (RNS) was higher in EOMG (p = 0.026). Thymoma was more frequent in LOMG (p = 0.017) and thymic hyperplasia was more frequent in EOMG (p < 0.001). Hyperthyroidism was more common in EOMG (p = 0.017) and diabetes was more common in LOMG (p < 0.001).

Conclusion: These results have potential significance for the recognition of clinical features and the determination of management strategies in EOMG and LOMG.