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Multicenter Study
. 2019 Sep:205:99-105.
doi: 10.1016/j.ajo.2019.04.017. Epub 2019 May 9.

Incidence, Epidemiology, and Transformation of Ocular Myasthenia Gravis: A Population-Based Study

Tina M Hendricks  1 , M Tariq Bhatti  2 , David O Hodge  3 , John J Chen  4
Affiliations
Multicenter Study

Incidence, Epidemiology, and Transformation of Ocular Myasthenia Gravis: A Population-Based Study

Tina M Hendricks et al. Am J Ophthalmol. 2019 Sep.

Erratum in

Abstract

Purpose: To establish the incidence of ocular myasthenia gravis (OMG) as well as identify determinants of transformation to generalized myasthenia gravis (GMG) using a population-based record-linkage system.

Design: Population-based, retrospective cohort study.

Methods: All adults (≥18 years) diagnosed with myasthenia gravis (MG) from January 1, 1990, through December 31, 2017, were identified using the Rochester Epidemiology Project. Sixty-five patients with MG were identified. Data were collected regarding symptom onset, diagnostic testing results, and conversion from OMG to GMG.

Results: Median follow-up time was 91 months (range 17-333 months). The annual incidence of MG was 2.20/100 000 with a mean age at diagnosis of 59 years (SD=17) and 62% male sex. Thirty-three (51%) of the 65 patients presented with OMG, providing an annual incidence of 1.13/100 000. Eighteen (55%) of the 33 patients presenting with OMG converted to GMG at a median time of 13 months (range 2-180 months). Sixteen (67%) of 24 OMG patients who were seropositive for acetylcholine receptor antibody (AchR Ab) converted to GMG at 5 years compared to 11% (1/9) of those who were seronegative (hazard ratio [HR], 8.2, P = .04). Ten (77%) of 13 OMG patients with a positive single-fiber electromyography (sfEMG) at diagnosis converted to GMG at 5 years, compared with 18% (2/11) of patients who had a negative sfEMG (HR, 5.5, P = .01).

Conclusions: In our population-based study, 51% (33/65) of patients with MG presented with isolated ocular involvement, with 55% (18/33) of these patients converting to GMG at some point in the course of their disease. Positive sfEMG and AchR Ab seropositivity at the time of diagnosis increased the risk of conversion to GMG.

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Conflict of interest statement

CONFLICT OF INTEREST: The authors report no relevant conflict of interest in submitting this article for publication.

Figures

Figure 1:
Figure 1:
Kaplan Meier curve depicting probability of conversion from ocular to generalized myasthenia gravis over time (months)
Figure 2:
Figure 2:
Kaplan Meier curve depicting probability of conversion over time (months) from ocular to generalized myasthenia gravis in patients who were acetylcholine receptor antibody seropositive compared to those who were not
Figure 3:
Figure 3:
Kaplan Meier curve depicting probability of conversion over time (months) from ocular to generalized myasthenia gravis in patients who had an abnormal single fiber electromyography test compared to those who were normal
See this image and copyright information in PMC

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