The incidence (number of new cases) and prevalence (sum of old and new cases) of myasthenia gravis (MG) both appear to be rising in the in the older U.S. population, according to a recently published study in Neurology.
Tracking trends in prevalence and incidence is crucial for clinicians, researchers and policymakers, as it reflects changing disease dynamics and helps in planning for future healthcare needs.
The study used data from the Medicare Fee-For-Service (FFS) claims database spanning 2006 to 2019. It included individuals aged 65 and above who had continuous coverage under Medicare Parts A and B, but excluded those with health maintenance organization coverage.
MG cases were identified using a validated claims-based algorithm, requiring at least two MG-related healthcare encounters separated by at least 28 days within a two-year period. Incidence was calculated for beneficiaries with new MG diagnoses following a year of continuous coverage, and mortality rates were tracked among those with MG compared to other Medicare beneficiaries.
Findings showed a notable increase in MG prevalence: In 2006–2007 there were 81 patients with MG per 100,000 Medicare beneficiaries, but by 2018–2019 that number had risen to 119 patients, representing approximately a 7% rise every two years.
The authors noted that the trend occured across all subgroups, including men and women, different age ranges, racial/ethnic groups and all geographic regions.
MG incidence rates also increased to a lesser degree, from 12.2 new cases per 100,000 person-years in 2008–2009 to 13 new cases in 2018–2019, or about a 2% increase every two years.
The authors hypothesized that the rising prevalence of MG in the older U.S. population could be driven by both a modest increase in new cases and lower mortality rates due to advances in treatment alternatives.
“In summary, we demonstrate that MG prevalence and incidence have consistently increased in the Medicare FFS–covered elderly US population over a 14-year period. The increase in MG prevalence occurred in all subgroups, irrespective of analyzed sex, age, race and ethnicity, and region,” noted the study’s authors.
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