Abstract
Purpose :
Patients with ocular myasthenia gravis (OMG) are frequently treated to improve ocular symptoms and prevent the development of severe generalized myasthenia gravis (GMG). But the varying progression rates lead to a debated issue of prognosis. We aim to assess the dynamics of change toward GMG and remission among patients with OMG.
Methods :
A retrospective cohort study was performed in 92 patients diagnosed as OMG. Time from onset of symptoms of OMG to GMG was analyzed against demographic variables, clinical findings, initial investigation results and treatment regimens using the Kaplan–Meier survival curve and multivariate Cox proportional regression analysis. The proportion of clinical remission was analyzed from the follow-up visits of both OMG and GMG patients.
Results :
The mean age of the patients was 46.7±14.3 years with a median (IQR) follow-up time of 2.3 (1.2-4.4) years. Twenty-eight (30.4%) patients developed GMG. The overall 1-year, 2-year and 5-year cumulative probabilities of encountering a GMG event were 15.1%, 27.0% and 34.9%, respectively. Patients with thymus abnormality had a higher probability compared to normal findings (adjusted hazard ratio (aHR) 8.3, 95%CI 2.4-28.2) and patients with a positive response to repetitive nerve stimulation (RNS) studies had a significantly higher risk than those with negative results (aHR 5.1, 95%CI 1.1-23.5). Age group, symptoms and signs, antinuclear factor and treatment options were not significant predictors. During the first year after diagnosis, 71% of the visits were in remission state, 23% had OMG and 6% had GMG. After the first year, nearly 90% of the visits attained remission.
Conclusions :
Within 5 years, our OMG patients had a lower risk of developing GMG compared to those reported in western countries and attained remission in more than two-thirds during the first year of follow-up. The fact that thymus abnormality and positive RNS test predicted transition toward GMG may suggest the need for a routine work-up of the thymus gland and an electrophysiological test.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.