Mortality in generalized myasthenia gravis among Medicare beneficiaries in the United States.

Abstract

Background: Data on mortality risk and its predictors among elderly patients with generalized myasthenia gravis (gMG) in the United States remain limited.

Methods: A prevalent cohort of Medicare Fee-for-Service beneficiaries with gMG and those without MG were identified using data from 01/2018 to 12/2023. Patients without MG were matched 10:1 to the gMG cohort on age and index year. Cohorts were weighted using overlap propensity scores on demographic and clinical characteristics. Mortality was assessed using Kaplan-Meier and Cox proportional hazards models from the index date (gMG cohort: random gMG-related visit; non-MG cohort: random medical visit) until death, end of data, or loss of eligibility. Predictors of all-cause mortality were evaluated among the gMG cohort using multivariable Cox regression.

Results: The study included 37,321 patients with gMG and 373,210 patients without MG (mean age: 74 years; 47% female). Patients with gMG had 8% higher mortality risk at 12 months and 7% higher risk at 24 and 36 months than those without MG (all p < 0.001). Among patients with gMG, mortality risk increased with older age (by 430% for ages ≥85 vs <65 years), male sex (by 25%), dual Medicare-Medicaid eligibility (by 17%), MG exacerbation (by 15%) and crisis (by 16%), and most comorbidities (all p < 0.05).

Conclusions: Mortality risk is elevated in Medicare beneficiaries with gMG relative to those without MG. In gMG, mortality risk is higher among men and increases with age, disease severity, and comorbidities. Findings underscore the complexity of managing gMG alongside comorbidities in elderly patients.