Factors Affecting Generalization of Ocular Myasthenia Gravis in Patients With Positive Acetylcholine Receptor Antibody

Am J Ophthalmol. 2020 Jan;209:10-17. doi: 10.1016/j.ajo.2019.09.019. Epub 2019 Sep 25.

Abstract

Purpose: To evaluate the associated factors of conversion of ocular myasthenia gravis (OMG) to generalized myasthenia gravis (GMG) among patients with seropositive acetylcholine receptor antibody (AchR Ab).

Design: Retrospective cohort study.

Methods: Setting: Retrospective chart review.

Patient: Seventy-one OMG patients with seropositive AchR Ab presented during July 2009 and December 2016. The exclusion criteria were patients who (1) first presented with GMG, (2) were unable to identify the time of onset of OMG or GMG, (3) were unable to provide information about previous treatments before the onset of GMG, and (4) had incomplete or lost medical records.

Observation procedure: We collected demographic and clinical characteristics, including onset of OMG and GMG, presence of other autoimmune disorders, history of smoking, presence of thymic abnormalities, and medications received.

Main outcome measures: Conversion to GMG and time to conversion.

Results: Thirty-six patients experienced conversion to GMG. Overall incidence of GMG was 14 (95% confidence interval [CI] 10.09-19.4) per 100 patient-years. Probability of conversion at 2 years was .37 (95% CI .27-.49). Overall median conversion time was 4.97 years. Cox proportional hazard model showed that risk factors were female sex (HR 2.52, 95% CI 1.04-6.10), history of smoking (HR 3.42, 95% CI 1.40-8.45), and thymic abnormalities (HR 1.82, 95% CI 0.91-3.67). Protective factors against conversion to GMG were receiving immunosuppressive agents (HR 0.42, 95% CI 0.19-0.97) and pyridostigmine (HR 0.37, 95% CI 0.14-0.93).

Conclusions: OMG patients with seropositive AchR Ab should be informed that taking pyridostigmine and/or immunosuppressive agents as well as smoking cessation might prevent conversion to GMG.

MeSH terms

  • Adult
  • Aged
  • Autoantibodies / blood*
  • Autoimmune Diseases / diagnosis*
  • Autoimmune Diseases / drug therapy
  • Autoimmune Diseases / immunology
  • Eye Diseases / diagnosis*
  • Eye Diseases / drug therapy
  • Eye Diseases / immunology
  • Female
  • Humans
  • Immunosuppressive Agents / therapeutic use
  • Incidence
  • Male
  • Middle Aged
  • Myasthenia Gravis / diagnosis*
  • Myasthenia Gravis / drug therapy
  • Myasthenia Gravis / immunology
  • Proportional Hazards Models
  • Receptors, Cholinergic / immunology*
  • Retrospective Studies
  • Risk Factors
  • Time Factors

Substances

  • Autoantibodies
  • Immunosuppressive Agents
  • Receptors, Cholinergic