Survey of epidemiology, clinical picture and current treatments for elderly‐onset (≥ 65 years) patients with myasthenia gravis in Nagano Prefecture, Japan

Background Our previous population-based study in 1982 – 2001, Nagano Prefecture, Japan, indicated increased numbers of patients with elderly-onset (≥ 65) myasthenia gravis (MG). Aim We performed a retrospective survey in 2002 – 2012 in the same area, and investigated the epidemiology, clinical picture, and treatments for MG. Methods Questionnaires were sent to 23 hospitals and patient records were reviewed. Patients were classified into the non-elderly-onset (15 – 64, n = 136) or elderly-onset (≥ 65, n = 78) group. The questionnaires included details of sex, age/date at onset, initial symptoms, disease severity, association with thymoma, and treatments. Post-intervention status and maximum/maintenance dose of prednisolone were investigated. Results The rate of elderly-onset MG patients increased in 2002 – 2012 despite correction for increases in the elderly population. The ratio of MGFA class I was higher, and that of class Πb was lower, and thymectomy rate in non-thymomatous generalized MG patients was lower in the elderly-onset group. There was no marked difference in the rate of intensive treatments (plasma exchange, intravenous immunoglobulin, etc.) between the groups. Immunosuppressive therapies (prednisolone, calcineurin inhibitors) were applied frequently in both groups, while calcineurin inhibitor use rate and mean maximal dose of prednisolone were lower, and the “minimum manifestation status with prednisolone ≤ 5 mg” rate was higher in the elderly-onset group. Conclusion This study suggested that a low or moderate dose of prednisolone can be fully effective in many elderly-onset MG patients, and some may not require calcineurin inhibitors or thymectomy to reduce prednisolone dose. This article is protected by copyright. All rights reserved.