Characteristics of myasthenia gravis according to onset-age: Japanese nationwide survey

Hiroyuki Murai, Natsumi Yamashita, Makoto Watanabe, Yoshiko Nomura, Masakatsu Motomura, Hiroaki Yoshikawa, Yosikazu Nakamura, Naoki Kawaguchi, Hiroshi Onodera, Shigeru Araga, Noriko Isobe, Masaki Nagai, Jun Ichi Kira

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Abstract

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.

Original languageEnglish
Pages (from-to)97-102
Number of pages6
JournalJournal of the Neurological Sciences
Volume305
Issue number1-2
DOIs
Publication statusPublished - Jun 15 2011

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Myasthenia Gravis
Age of Onset
Japan
Thymoma
Cholinergic Receptors
Surveys and Questionnaires
Hyperplasia
Antibodies
Incidence
Population

All Science Journal Classification (ASJC) codes

  • Neurology
  • Clinical Neurology

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Characteristics of myasthenia gravis according to onset-age : Japanese nationwide survey. / Murai, Hiroyuki; Yamashita, Natsumi; Watanabe, Makoto; Nomura, Yoshiko; Motomura, Masakatsu; Yoshikawa, Hiroaki; Nakamura, Yosikazu; Kawaguchi, Naoki; Onodera, Hiroshi; Araga, Shigeru; Isobe, Noriko; Nagai, Masaki; Kira, Jun Ichi.

In: Journal of the Neurological Sciences, Vol. 305, No. 1-2, 15.06.2011, p. 97-102.

Research output: Contribution to journalArticle

Murai, H, Yamashita, N, Watanabe, M, Nomura, Y, Motomura, M, Yoshikawa, H, Nakamura, Y, Kawaguchi, N, Onodera, H, Araga, S, Isobe, N, Nagai, M & Kira, JI 2011, 'Characteristics of myasthenia gravis according to onset-age: Japanese nationwide survey', Journal of the Neurological Sciences, vol. 305, no. 1-2, pp. 97-102. https://doi.org/10.1016/j.jns.2011.03.004
Murai, Hiroyuki ; Yamashita, Natsumi ; Watanabe, Makoto ; Nomura, Yoshiko ; Motomura, Masakatsu ; Yoshikawa, Hiroaki ; Nakamura, Yosikazu ; Kawaguchi, Naoki ; Onodera, Hiroshi ; Araga, Shigeru ; Isobe, Noriko ; Nagai, Masaki ; Kira, Jun Ichi. / Characteristics of myasthenia gravis according to onset-age : Japanese nationwide survey. In: Journal of the Neurological Sciences. 2011 ; Vol. 305, No. 1-2. pp. 97-102.
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abstract = "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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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

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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.

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