Age and Treatment Efficacy in Myasthenia Gravis: A Systematic Review, Meta-Analysis, and Meta-Regression

Myasthenia gravis (MG) is increasingly concentrated in older adults, and age may shift the balance of benefit and risk for MG therapies. This study seeks to evaluate the effect of age on treatment efficacy in clinical trials of MG.

PubMed and Cochrane Library were searched and clinical trials enrolling adults with MG that reported the quantitative myasthenia gravis (QMG) score and the myasthenia gravis activities of daily living (MG-ADL) scale were included. Of 2214 records identified, 18 trials met inclusion criteria. Random-effects meta-analysis was used to pool treatment effects, and random-effects meta-regression evaluated trial-level mean baseline age as a modifier of treatment efficacy.

Eighteen trials published from 2017 to 2025 included 1823 participants (982 assigned to treatment and 841 to control). Pooled effects favored treatment over control for the QMG (MD -2.402; 95% CI, -3.099 to -1.706; $I^2$  = 60.7%) and MG-ADL scores (MD, -1.591; 95% CI, -1.874 to -1.309; $I^2$  = 0.0%). In meta-regression, higher mean trial age was associated with attenuation of treatment benefit on the QMG scale (β per 10 years, 1.21; 95% CI, 0.02 to 2.42; p = 0.047). This effect was most pronounced for FcRn inhibitors. No association was observed for the MG-ADL score (β per 10 years, 0.08; 95% CI, -0.50 to 0.66; p = 0.779).

In this meta-analysis, older trial populations showed smaller treatment-related improvements in the QMG but not in the MG-ADL score. These findings suggest that age may contribute to differences in treatment effects across MG trials.