Both the incidence and prevalence of myasthenia gravis (MG) in the United States have increased in recent years, according to research recently presented at the annual meeting of the American Association of Neuromuscular and Electrodiagnostic Medicine.
Incidence and prevalence are terms used to describe the frequency of a disease in a population: Incidence means the number of new cases, while prevalence refers to the percentage of a population with the disease. Together, these numbers indicate that more Americans are living with MG.
To analyze U.S. cases of MG, the researchers reviewed claims data from the Optum Clinformatics Data Mart between January 2016 and June 2024. Persons included in the study were adults aged 18 years and older with either two outpatient claims for MG or one inpatient and one outpatient claim. A one-year washout period was applied when determining new cases in order to prevent individuals with previously diagnosed MG from being counted as new incidents.
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The researchers found that the annual incidence rate of MG increased from 10.6 to 13.8 per 100,000 person-years during the timeframe studied. Put another way, if the authors had observed 100,000 people for a year they would expect 10.6 to be diagnosed with MG during a year at the beginning of the study period and 13.8 to be diagnosed during a year at the end.
The researchers identified the highest number of new MG cases — 3,908 — among adults older than 75.
The overall prevalence of people living with MG was 44.1 per 100,000 persons, with an 18% increase from 2021 to 2023.
Their analysis also documented high rates of disease exacerbations, highlighting the continued burden of MG among adults.
At the start of the study, the rate of new MG exacerbations ranged from 53.3 to 65.9 per 100 person-years. There were 785 prevalent and 1,239 incident patients who experienced an exacerbation on the day they were indexed into the study.
“The observed increase in MG incidence and prevalence may be due to heightened health care provider awareness, better survival rates due to treatment advancements and potentially a surge in reporting post-COVID pandemic,” the authors wrote.
They added that the high rate of exacerbations indicates that care remains suboptimal for many patients, underscoring the need for more effective, targeted therapies to achieve sustained disease control and improve quality of life.
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