Disease-Modifying Treatments for Myasthenia Gravis

Inclusion Criteria: Participants eligible for inclusion in this study must fulfill all of the following criteria: 1. Age ≥ 18 years of age 2. Acquired autoimmune MG, with weakness and confirmed by one or more of the following: 1. Elevated AChR or MuSK antibodies 2. Unequivocal response to cholinesterase inhibitors 3. Abnormal RNS or increased jitter (without nerve or muscle disease sufficient to produce a decrement or increased jitter) 3. Patients seen initially at the participating center after January 1, 2017. 4. Patients on pyridostigmine at the first evaluation at the participating center ("baseline visit") may be included if pyridostigmine was started ≤3 months before the baseline visit. 5. Patients who received corticosteroids \>90 days prior to baseline visit for a non-MG indication may be included. (Patients who have received corticosteroids for a non-MG indication between 31 and 90 days before baseline visit will be evaluated by the primary investigators on a case by case basis to determine if the extent and dose of corticosteroid could have impacted the course of MG or symptoms of MG.) Exclusion Criteria: Patients fulfilling any of the following criteria are not eligible for inclusion in this study. No additional exclusions may be applied by the investigator, in order to ensure that the study population will be representative of all eligible participants. 1. Patients with non-autoimmune MG (congenital myasthenic syndromes, drug-induced MG) 2. Patients on immunosuppressive agents at the baseline visit. 3. Patients who have previously received steroids for the treatment of MG. 4. Patients with steroid use for a non-MG indication \< 30 days prior to the baseline visit. 5. Patients with previous thymectomy, IVIg or plasma exchange, or treatment with a non-steroidal immunosuppressive agent (azathioprine, mycophenolate mofetil cyclosporine, methotrexate, cyclophosphamide, tacrolimus, rituximab, or any investigational immunosuppressive agent). Patients who have outcomes measured within 24 hours after initiation of IVIg or PLEX are acceptable.