Prospective cohort study reveals high incidence of myasthenia gravis in older adults, highlighting age-dependent treatment needs.
Key Points
To assess the incidence, age distribution, clinical course, and treatment outcomes of myasthenia gravis onset across age groups over a 10-year period.
Prospective population-based study recruiting all individuals diagnosed with myasthenia gravis (N = 40) in Osona County, Spain (population 142,337 in 2005) between January 2001 and December 2010.
Diagnosis confirmed via clinical evaluation, edrophonium testing, electrophysiological examination, or serum antibody detection (antiacetylcholine receptor or anti-MuSK antibodies).
Calculated annual cumulative incidence and compared clinical presentations, comorbid autoimmune conditions, and therapeutic responses between patients aged <65 and ≥65 years.
Annual incidence rate was 28.0 cases per million inhabitants (95% CI, 19.3–36.7) with median onset at 74.1 years; incidence rose from 49.8 per million (aged 65–74) to 157.64 per million (aged 75–84) and 170.89 per million (aged ≥85).
Older adults (≥65 years) exhibited higher rates of concurrent autoimmune conditions (38.4% [10/26] vs 14.2% [2/14] in those <65 years) while maintaining comparable baseline disease severity (P = .41).
Favorable response to therapy occurred in surviving patients; older adults required lower alternate-day maintenance prednisone doses (10–20 mg in 5/18 vs 30–40 mg in 5/12) and less frequent additional immunosuppression (16.6% [3/18] vs 41.6% [5/12]) than younger individuals.