title: Does change in acetylcholine receptor antibody level correlate with clinical change in myasthenia gravis?
abstract: BACKGROUND
  The objective of this study is to determine if change in acetylcholine receptor antibody (AChR-ab) levels reflects change in clinical severity in patients with myasthenia gravis (MG).
  
  
  METHODS
  We reviewed results from a prospective trial in MG and from all 85 patients in an MG Clinic who had AChR-ab determinations performed at least twice by the same commercial laboratory.
  
  
  RESULTS
  Change in AChR-ab levels correlated only weakly with change in clinical severity. AChR-ab levels fell in 92% of patients who improved and in 63% who did not. A fall in AChR-ab level had a positive predictive value for clinical improvement of 83% and a negative predictive value of only 59%.
  
  
  CONCLUSIONS
  AChR-ab levels fell in almost all patients who improved, but also in most patients who did not. Thus, we do not recommend commercially available AChR-ab levels as a biomarker of improvement in MG. However, antibody levels might be useful as a marker for inadequate immunotherapy.
authors.affiliation: Neuromuscular Division, Department of Neurology, Box 3403, Duke University Medical Center, Durham, North Carolina, 27710.
authors.forename: Donald B
authors.initials: DB
authors.lastname: Sanders
authors.forename: Ted M
authors.initials: TM
authors.lastname: Burns
authors.forename: Gary R
authors.initials: GR
authors.lastname: Cutter
authors.forename: Janice M
authors.initials: JM
authors.lastname: Massey
authors.forename: Vern C
authors.initials: VC
authors.lastname: Juel
authors.forename: Lisa
authors.initials: L
authors.lastname: Hobson-Webb
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D016208:Databases, Factual / Q000639:trends; D006801:Humans; D009157:Myasthenia Gravis / Q000097:blood* / Q000175:diagnosis* / Q000628:therapy; D011446:Prospective Studies; D011950:Receptors, Cholinergic / Q000097:blood*; D012042:Registries
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D011950:Receptors, Cholinergic
keywords: MG Composite; QMG score; acetylcholine receptor antibody; clinical trials; myasthenia gravis; outcome measures