Objective:

To characterize the comorbidity burden and steroid usage patterns in Medicare fee-for-service beneficiaries with generalized myasthenia gravis (gMG) in the US.

Background:

gMG is a rare, autoimmune, neuromuscular disease characterized by fluctuating fatigable muscle weakness. The aging patient population and corticosteroid-related adverse effects contribute to the high comorbidity burden associated with gMG. Corticosteroids can exacerbate certain comorbidities; however, detailed information on comorbidities and gMG-directed steroid treatment in the US patient population is limited.

Design/Methods:

This retrospective observational cohort study collected patient data from the Inovalon 100% Medicare Parts A and B fee-for-service claims and 100% Part D prescription drug event claims between January 1, 2016, and December 31, 2021. Eligible patients were ≥18 years old, had been diagnosed with gMG, had continuous health plan enrollment (combined medical and pharmacy benefits) for 12 months before the index date, and were not enrolled in any clinical trial. Demographics and clinical characteristics, comorbidities, and treatment patterns were extracted for the overall patient population.

Results:

Data from 29,349 patients with gMG were collected. Key patient demographics: 88.8% of patients were White and 52.3% were male; median age at index was 75 years and mean Elixhauser comorbidity score was 6.1. Common baseline comorbidities included complicated hypertension (70.0%), hyperlipidemia (60.2%), cardiac arrhythmia (29.5%), uncomplicated diabetes (29.5%), and sleep disorder (26.4%). During follow up, 58.7% of patients received an oral corticosteroid to manage gMG symptoms, of which 53.8% reported long-term (≥3 continuous months) use. Among patients with 6 months of continuous enrollment and long‑term oral corticosteroid use (n=7,142), mean starting dose (± standard deviation) was 16.3 ± 17.9 mg/day, and 56.8% of these patients had no dose reduction during the study (mean duration of follow up: 716.3 days).

Conclusions:

Patients with gMG have high rates of comorbidities, which should be taken into consideration when selecting gMG therapies such as oral corticosteroids.