The quantitative myasthenia gravis score: comparison with clinical, electrophysiological, and laboratory markers

J Clin Neuromuscul Dis. 2012 Jun;13(4):201-5. doi: 10.1097/CND.0b013e31824619d5.

Abstract

Objective: To determine whether the quantitative myasthenia gravis score (QMGS) accurately represents disease severity in patients with myasthenia gravis (MG).

Methods: One hundred thirty-five patients with MG from 2 previous randomized studies were included. QMGS correlation with the Myasthenia Gravis Foundation of America (MGFA) score, quality of life scale, acetylcholine receptor antibodies (AChRAbs), and electrophysiological parameters was studied.

Results: The QMGS showed a good correlation with the MGFA scale (r² = 0.54, P < 0.0001), jitter (rs = 0.40, P < 0.0001), and 15-item quality of life scale (rs = 0.41, P = 0.007) and was less well correlated with the 60-item myasthenia gravis-specific quality of life survey and other electrophysiological markers. No correlation was demonstrated with AchRAb titers, but AchRAb-positive patients had higher QMGS (14.2 ± 4.5) than AchRAb-negative patients (12.0 ± 3.7, P = 0.008).

Conclusions: These results demonstrate that the QMGS is a valid marker for disease severity as shown by the MGFA scale, quality of life scale, and jitter, supporting the use of the QMGS as a primary outcome measure in clinical trials of MG.

Publication types

  • Comparative Study

MeSH terms

  • Action Potentials / physiology*
  • Adult
  • Aged
  • Analysis of Variance
  • Antibodies / blood*
  • Disability Evaluation
  • Double-Blind Method
  • Electric Stimulation
  • Electromyography
  • Female
  • Humans
  • Immunoglobulins, Intravenous / therapeutic use
  • Male
  • Middle Aged
  • Myasthenia Gravis / diagnosis*
  • Myasthenia Gravis / metabolism
  • Myasthenia Gravis / physiopathology*
  • Myasthenia Gravis / therapy
  • Plasmapheresis / methods
  • Quality of Life
  • Randomized Controlled Trials as Topic
  • Receptors, Cholinergic / immunology
  • Severity of Illness Index*
  • Statistics, Nonparametric

Substances

  • Antibodies
  • Immunoglobulins, Intravenous
  • Receptors, Cholinergic