title: Complete stable remission and autoantibody specificity in myasthenia gravis.
abstract: OBJECTIVE
  Patients with myasthenia gravis (MG) are subgrouped as acetylcholine receptor (AChR)-positive, muscle-specific kinase (MuSK)-positive, and AChR/MuSK-negative MG (or double negative [DN]) on the basis of autoantibody assay. We investigated the relationships between autoantibody specificity, main clinical features, and outcome of the disease, in particular the occurrence of complete stable remission (CSR), by means of a retrospective study on a cohort of 677 Italian patients with MG.
  
  
  METHODS
  A total of 517 (76%) patients with AChR-positive MG, 55 (8%) patients with MuSK-positive MG, and 105 (16%) patients with DN MG were included in the study. Kaplan-Meier and Cox proportional hazard regression analyses were used to evaluate associations between baseline characteristics, antibody specificity, and CSR.
  
  
  RESULTS
  Clinical stage at onset and at maximal worsening was more severe for MuSK-positive patients: bulbar impairment at maximal worsening was found in 83.6% of MuSK-positive patients compared with 58.6% of AChR-positive patients and 43.8% of DN patients (p < 0.001). Baseline characteristics of AChR-positive and DN patients were similar. CSR was observed in 3.6% of MuSK-positive patients compared with 22.2% of AChR-positive and 21.9% of DN patients. In the whole MG cohort, onset before age 40 (hazard ratio [HR] = 1.96, 95% confidence interval [CI] 1.27-3.02, p = 0.002) and ocular and generalized clinical stages at maximal worsening were associated with CSR (ocular, HR = 8.05, 95% CI 1.88-34.53, p = 0.005; generalized, HR = 3.71, 95% CI 1.16-11.90, p = 0.023; bulbar, HR = 3.16, 95% CI 1.00-10.05, p = 0.051).
  
  
  CONCLUSIONS
  MuSK antibodies identify a clinically distinguishable, more severe form of MG since the disease onset, with a lower occurrence of CSR. These features should be considered by the clinician in the management of this particular form of MG.
authors.affiliation: Neurology IV, Neurological Institute Foundation Carlo Besta, Milan, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Baggi
authors.forename: Francesca
authors.initials: F
authors.lastname: Andreetta
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Maggi
authors.forename: Paolo
authors.initials: P
authors.lastname: Confalonieri
authors.forename: Lucia
authors.initials: L
authors.lastname: Morandi
authors.forename: Franco
authors.initials: F
authors.lastname: Salerno
authors.forename: Pia
authors.initials: P
authors.lastname: Bernasconi
authors.forename: Cristina
authors.initials: C
authors.lastname: Montomoli
authors.forename: Massimo
authors.initials: M
authors.lastname: Barberis
authors.forename: Renato
authors.initials: R
authors.lastname: Mantegazza
authors.forename: Carlo
authors.initials: C
authors.lastname: Antozzi
mesh_terms: D000328:Adult; D017668:Age of Onset; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis*; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D019635:Neurosurgical Procedures; D010951:Plasma Exchange; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology; D011950:Receptors, Cholinergic / Q000276:immunology; D012189:Retrospective Studies; D012727:Sex Characteristics; D013950:Thymus Gland / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D001323:Autoantibodies; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases