TY - JOUR
T1 - Characteristics of myasthenia gravis according to onset-age
T2 - Japanese nationwide survey
AU - Murai, Hiroyuki
AU - Yamashita, Natsumi
AU - Watanabe, Makoto
AU - Nomura, Yoshiko
AU - Motomura, Masakatsu
AU - Yoshikawa, Hiroaki
AU - Nakamura, Yosikazu
AU - Kawaguchi, Naoki
AU - Onodera, Hiroshi
AU - Araga, Shigeru
AU - Isobe, Noriko
AU - Nagai, Masaki
AU - Kira, Jun Ichi
N1 - Funding Information:
A nationwide MG survey was conducted by the Research Committees of Neuroimmunological Diseases and of Epidemiology of Intractable Diseases, sponsored by the Ministry of Health, Labour and Welfare, Japan. The study was approved by the Kyushu University Ethics Committee. The survey was carried out in two steps. First, a preliminary survey was undertaken to determine the prevalence and the approximate number of patients with MG in Japan, and a second survey was then conducted using a questionnaire to gather clinical information about each patient. The hospitals included in the study were randomly selected from the directory of all registered hospitals throughout Japan. Selection was made according to a stratification based on the number of beds in each hospital, whereby a higher number of beds led to a higher probability of being selected [19] . The sampling rates were approximately 5%, 10%, 20%, 40%, 80%, and 100% for general hospitals with 20–99 beds, 100–199 beds, 200–299 beds, 300–399 beds, 400–499 beds, and 500 or more beds, respectively. All university hospitals, as well as clinics in which a substantial number of MG patients were seen, were also surveyed.
Funding Information:
The authors thank Dr. Tetsuro Konishi for providing helpful advice. This work was supported in part by grants from the Neuroimmunological Disease Research Committee and the Epidemiology of Intractable Diseases Research Committee from the Ministry of Health, Labour and Welfare, Japan .
PY - 2011/6/15
Y1 - 2011/6/15
N2 - Objective: To clarify the prevalence and clinical characteristics of myasthenia gravis (MG) in Japan. Methods: We performed a nationwide epidemiological survey of MG in Japan. The clinical features were compared among five groups of patients, divided according to onset age. A generalized additive model (GAM) was used to assess the linearity of these relationships. Results: A total of 8542 patients were reported, and detailed data were analyzed for 3141 patients. The estimated number of MG patients in Japan was 15,100, giving a prevalence of 11.8 per 100,000. Elderly-onset MG (≥ 65 years) accounted for 7.3% in 1987 (adjusted for population in 2005), but this had increased to 16.8% in 2006. Infantile-onset MG (0-4 years) accounted for 10.1% in 1987, and was still as high as 7.0% in 2006. The rate of ocular MG was highest (80.6%) in infantile-onset and lowest (26.4%) in early-onset disease, but the rate rose again in the late-onset group. GAM analysis of the ocular form showed a U-shaped curve, with a dip in the 20s. Anti-acetylcholine receptor antibodies were positive in only 50% of infantile-onset, but nearly 90% of elderly-onset patients. GAM analyses assessing the concurrence of thymoma and hyperplasia both showed reversed U-shapes, with peaks in the 50s and 20s-40s, respectively. Conclusions: Persistent high incidence of infantile-onset disease and clinical heterogeneity according to onset age are characteristic features of MG in Japan.
AB - Objective: To clarify the prevalence and clinical characteristics of myasthenia gravis (MG) in Japan. Methods: We performed a nationwide epidemiological survey of MG in Japan. The clinical features were compared among five groups of patients, divided according to onset age. A generalized additive model (GAM) was used to assess the linearity of these relationships. Results: A total of 8542 patients were reported, and detailed data were analyzed for 3141 patients. The estimated number of MG patients in Japan was 15,100, giving a prevalence of 11.8 per 100,000. Elderly-onset MG (≥ 65 years) accounted for 7.3% in 1987 (adjusted for population in 2005), but this had increased to 16.8% in 2006. Infantile-onset MG (0-4 years) accounted for 10.1% in 1987, and was still as high as 7.0% in 2006. The rate of ocular MG was highest (80.6%) in infantile-onset and lowest (26.4%) in early-onset disease, but the rate rose again in the late-onset group. GAM analysis of the ocular form showed a U-shaped curve, with a dip in the 20s. Anti-acetylcholine receptor antibodies were positive in only 50% of infantile-onset, but nearly 90% of elderly-onset patients. GAM analyses assessing the concurrence of thymoma and hyperplasia both showed reversed U-shapes, with peaks in the 50s and 20s-40s, respectively. Conclusions: Persistent high incidence of infantile-onset disease and clinical heterogeneity according to onset age are characteristic features of MG in Japan.
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U2 - 10.1016/j.jns.2011.03.004
DO - 10.1016/j.jns.2011.03.004
M3 - Article
C2 - 21440910
AN - SCOPUS:79955702892
SN - 0022-510X
VL - 305
SP - 97
EP - 102
JO - Journal of the Neurological Sciences
JF - Journal of the Neurological Sciences
IS - 1-2
ER -