Evaluation of clinical features and prognosis of myasthenia gravis in adults based on the age of onset: A retrospective study from a single center of 30 years MG registry

Objective: We aimed to evaluate the demographic, clinical, and immunological features of myasthenia gravis (MG) in adults according to the age of onset and to investigate the effect on prognosis.
Methods: A total of 332 patients with MG were included in the study. Patients were classified into three age subgroups: early-onset MG (EOMG), late-onset MG (LOMG), and very late-onset MG. Complete stable remission, pharmacological remission, and minimal manifestations for 1 year were assessed as a good prognosis on the MGFA-PIS scale. Improved, unchanged, worse, exacerbation and death due to MG were assessed as having a poor prognosis.
Results: There were 177 (53.3%) female and 155 male (46.7%) patients with a mean age of 55.3 ± 17.4. A total of 176 patients (53%) were classified as EOMG, 94 patients (28.3%) as LOMG, 62 (18.7%) as very late-onset MG, 282 patients (84.9%) as anti-AChR positive, 21 patients (6.3%) as anti-MuSK positive, and two patients (0.6%) as anti- AChR and anti-MuSK double-positive. While 95.6% of patients with a good prognosis had MGFA-1 at the onset of the disease, 40.3% of patients with a poor prognosis had MGFA-2B. At the end of the clinical follow-up, the MGFA-PIS score was evaluated, 55.1% of the patients had a good prognosis, while 44.9% had a poor prognosis.
Conclusions: Age at disease onset was not associated with prognosis. Presence of generalized MG subtype and thymoma, anti-MuSK positivity, hospitalization in the intensive care unit, myasthenic crisis, IVIG administration, plasmapheresis, comorbidity, 2 or more comorbidities were found to have significant association with poor prognosis.