Clinical characteristics and outcome of treatment-refractory myasthenia gravis -a retrospective study

Objective This study aimed to investigate the frequency, clinical characteristics, and outcomes of treatment-refractory myasthenia gravis (MG) in a Chinese cohort. Methods A retrospective cohort of 277 MG patients was conducted between August 2016 and May 2023. Patients were classified as refractory if their Myasthenia Gravis Foundation of America post-intervention status (MGFA-PIS) was categorized as “unchanged” or “worse”. Additionally, patients with persistent symptoms and functional limitations despite at least 12 months of concurrent immunosuppressive therapy, including adequately dosed steroids and two other immunosuppressive drugs, were also classified as refractory. The clinical features and outcomes at the end of follow-up of drug-refractory patients were compared with those of drug-responsive patients. Results Of the 277 patients, 36 were unequivocally diagnosed with refractory MG. Treatment-refractory patients frequently presented at a younger age, with a generalized form of the disease, and with bulbar/or respiratory symptoms at onset. These patients also exhibited higher disease severity than non-drug-refractory patients. Furthermore, patients classified as drug-resistant experienced a longer interval between disease onset and the initiation of immunotherapy. At the end of follow-up, poor outcome was more frequently found in treatment-refractory MG patients. Conclusion This study found that 13% of MG patients were classified as drug-refractory. There is a need for new, more specific drugs to treat drug-refractory MG patients.