title: The quantitative myasthenia gravis score:  comparison with clinical, electrophysiological, and laboratory markers.
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.
authors.affiliation: Division of Neurology, Department of Medicine, Toronto General Hospital, University Health Network, Toronto, Canada.
authors.forename: Carolina
authors.initials: C
authors.lastname: Barnett
authors.forename: Hans
authors.initials: H
authors.lastname: Katzberg
authors.forename: Maryam
authors.initials: M
authors.lastname: Nabavi
authors.forename: Vera
authors.initials: V
authors.lastname: Bril
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000906:Antibodies / Q000097:blood*; D004185:Disability Evaluation; D004311:Double-Blind Method; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology* / Q000628:therapy; D010956:Plasmapheresis / Q000379:methods; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D011950:Receptors, Cholinergic / Q000276:immunology; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric
chemical_list: D000906:Antibodies; D016756:Immunoglobulins, Intravenous; D011950:Receptors, Cholinergic