Objective:

To estimate the incidence and prevalence of myasthenia gravis (MG) in the United States (US).

Background:

MG is a rare autoimmune disease characterized by muscle weakness caused by the binding of autoantibodies at the neuromuscular junction. In the EU, incidence and prevalence of MG have increased over time due to increased diagnosis and decreased mortality; however recent data in the US are lacking.

Design/Methods:

Clarivate’s Real World Data Product, including Medical claims (Commercial, Medicare, and Medicaid) and electronic health records, representing over 300 million patients in the US from 2011 to present was used for this retrospective analysis.  The incidence and prevalence of MG were calculated for the year 2021 using population estimates from the US Census.  Sex- and age-specific incidence and prevalence estimates were calculated for the following age groups: <2, 2-5, 6-11, 12-17, 18-49, 50-64, and 65+ years.

Results:

In 2021, the overall incidence of MG was 3.2 per 100,000 with similar estimates for males and females (3.2 vs. 3.1 per 100,000, respectively). Total prevalence was estimated to be 37.0 per 100,000 with sex-specific estimates being comparable at 37.3 and 36.7 per 100,000 for males and females, respectively.  The incidence and prevalence of MG increased with age, with incidence estimates of 0.3, 0.5, 0.2, 0.4, 1.5, 4.0, and 10.2 per 100,000 and prevalence estimates calculated as 0.4, 2.1, 3.7, 5.6, 18.3, 47.9, and 116.8 per 100,000 among those who were <2, 2-5, 6-11, 12-17, 18-49, 50-64, and 65+ years of age, respectively.  

Conclusions:

These estimates of the incidence and prevalence of MG in the US are higher than older reported estimates and are consistent with European data that demonstrate an increase in the incidence and prevalence of MG.  Updated prevalence estimates allow for more accurate quantification of the burden of disease associated with MG.