Insights into the classification of myasthenia gravis

Tetsuya Akaishi, Takuhiro Yamaguchi, Yasushi Suzuki, Yuriko Nagane, Shigeaki Suzuki, Hiroyuki Murai, Tomihiro Imai, Masakatsu Motomura, Kazuo Fujihara, Masashi Aoki, Kimiaki Utsugisawa

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16 Citations (Scopus)

Abstract

Background and Purpose: Myasthenia gravis (MG) is often categorized into thymoma-associated MG, early-onset MG with onset age <50 years, and late-onset MG with onset age ≥50 years. However, the boundary age of 50 years old between early- and late-onset MG remains controversial, and each category contains further subtypes. We attempted to classify MG from a statistical perspective. Methods: We analyzed 640 consecutive MG patients using two-step cluster analysis with clinical variables and discrimination analysis, using onset age as a variable. Results: Two-step cluster analyses categorized MG patients into the following five subtypes: ocular MG; MG with thymic hyperplasia (THMG); generalized anti-acetylcholine receptor antibody (AChR-Ab)-negative MG; thymoma-associated MG; and generalized AChR-Ab-positive (SP) MG without thymic abnormalities. Among these 5 subtypes, THMG showed a distribution of onset age skewed toward a younger age (p<0.01), whereas ocular MG and SPMG without thymic abnormalities showed onset age skewed toward an older age (p<0.001 and p<0.0001, respectively). The other 2 subtypes showed normal distributions. THMG appeared as the main component of early-onset MG, and ocular MG and SPMG without thymic abnormalities as the main components of late-onset MG. Discrimination analyses between THMG and ocular MG and/or SPMG without thymic abnormalities demonstrated a boundary age of 45 years old. Conclusions: From a statistical perspective, the boundary age between early- and late-onset MG is about 45 years old.

Original languageEnglish
Article numbere106757
JournalPloS one
Volume9
Issue number9
DOIs
Publication statusPublished - 2014 Sep 5

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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    Akaishi, T., Yamaguchi, T., Suzuki, Y., Nagane, Y., Suzuki, S., Murai, H., Imai, T., Motomura, M., Fujihara, K., Aoki, M., & Utsugisawa, K. (2014). Insights into the classification of myasthenia gravis. PloS one, 9(9), [e106757]. https://doi.org/10.1371/journal.pone.0106757