To describe the association between oral corticosteroid (OCS) use and related adverse effects (AEs) among myasthenia gravis (MG) patients.

MG is a rare disease characterized by autoantibody-driven impairment of neuromuscular junction activity. OCS are included in standard-of-care for MG, with long-term use often necessary for disease control. While OCS use is known to be associated with numerous AEs, there is a gap in understanding the long-term consequences of OCS use among MG patients.

This retrospective, longitudinal cohort study leveraged US claims data from Optum’s de-identified Clinformatics® Data Mart Database to identify MG patients (January 2016-March 2023) using diagnoses (ICD-10-CM G70.0x). Patients were divided into cohorts having no OCS use or, after ≥1 month of continuous OCS use post initial MG diagnosis, 0, 1, or 2 6-month periods of continuous exposure to prednisone-equivalent doses ≥5 mg/day during 12-month follow-up. Inverse probability treatment weighting balanced baseline characteristics across cohorts. Weighted prevalence ratios of select AEs (diabetes, fracture, hyperlipidemia, hypertension, infection, myocardial infarction, osteoporosis, stroke) were calculated.

After weighting, the cohorts with no OCS (n=3297) and 0 (n=418), 1 (n=872), and 2 (n=1243) 6-month periods of continuous OCS use were well-balanced. During follow-up, the 0-, 1-, and 2-period OCS cohorts had significantly increased infection risk relative to the no-OCS cohort: weighted prevalence ratios 1.6 (95% confidence interval [CI]: 1.1-2.1), 1.5 (1.2-2.0), and 1.6 (1.3-2.0), respectively. While osteoporosis risk was similar for the 0-period OCS cohort, the 1- and 2-period OCS cohorts had significantly increased risk relative to the no-OCS cohort: weighted prevalence ratios 1.2 (0.9-1.6), 1.5 (1.2-1.8), and 1.7 (1.4-2.0), respectively.

After adjusting for observable confounders, prolonged OCS exposure within the first year of initiation was associated with an elevated risk of certain AEs among MG patients. Clinicians may consider the risks associated with long-term OCS use.