Short-term and long-term prognoses in AChR-Ab positive very-late-onset myasthenia gravis patients

Very-late-onset myasthenia gravis (VLOMG) refers to myasthenia gravis (MG) with onset at age 65 or older. Current research on VLOMG prognosis remains limited, especially regarding factors influencing outcomes.

To identify the clinical factors that affect the short- and long-term prognosis of MG patients with an onset age ⩾65 years.

This was a single-center, retrospective cohort study of AChR-ab positive VLOMG patients, classified into two subgroups based on age of onset: sub-very-late-onset MG (S-VLOMG, onset age ⩾65 and <75 years), and super-late-onset MG (SLOMG, onset age ⩾75 years).

A total of 93 patients were included, including 75 in the S-VLOMG group and 18 in the SLOMG group. Clinical, therapeutic, and prognosis data were reviewed, and the Cox regression model was used to identify factors influencing short- and long-term prognosis.

Patient characteristics were well balanced between the groups. Overall, 49.5% of patients achieved minimal symptom expression (MSE) within 6 months and 86% within 24 months. There was no significant difference between the groups in the proportion achieving MSE at 6 months (p = 0.635) or 24 months (p = 0.714). The median time to achieve MSE was also comparable between the S-VLOMG and SLOMG groups (199.0 days vs 280.5 days, p = 0.463). Low baseline MG-ADL score and steroid therapy were associated with better short-term prognosis (p = 0.007 and p = 0.002, respectively). For long-term prognosis, baseline bulbar and limb involvement, time to treatment initiation, and use of immunosuppressants were significant factors (p = 0.025, p = 0.004, p = 0.025, and p < 0.0001, respectively). There were no significant differences in side effects or drug withdrawal rates between two groups.

This study demonstrated that AChR-ab positive VLOMG patients have a favorable prognosis and responded well to medication, with age and comorbidities showing no significant impact.