MOG‐Ab prevalence in optic neuritis and clinical predictive factors for diagnosis
Authors: Ducloyer Jean‐Baptiste 
Published: December 2022

Purpose: What is the proportion of MOG‐Ab among optic neuritis (ON) in adults and what would be the ON presentation for which MOG‐Ab should be tested?

Methods: Multicentric prospective study conducted during one year on all patients diagnosed with acute ON in all ophthalmologic units in hospitals of a region in western France.

Results: Sixty‐five patients were included. MOG‐Ab prevalence was 14% (9/65) during an acute ON and 13% (7/55) after exclusion of patients already diagnosed as multiple sclerosis (MS) (8) or MOG + ON (2). Compared to multiple sclerosis (MS) and clinically isolated syndrome (CIS), MOG + ON had no female preponderance (respectively 67% of men versus 22%, p < 0.05), were more often bilateral (44% versus 3%, p < 0.005) and associated with optic disc swelling (ODS) (78% versus 14%, p < 0.001). To predict MOG + ON, the combined factor “ODS or bilateral or recurrent ON” was the best compromise between positive predictive value (31% 95% CI [14;48]) and negative predictive value (100% [100;100]).

Discussion: These results corroborate other studies that estimated MOG‐Ab prevalence among ON: between 10 to 31% in four retrospective studies and 4% (2/51) in a prospective study. AQP4‐Ab prevalence is higher in Asia (36 to 42%) than in Europe (5%). Furthermore, our study supports the clinical findings of large retrospective collections of MOG + ON patients: MOG + ON occurs in similar age as MS without female preponderance, optic disc swelling and bilateral involvement are common, response to corticosteroid treatment is good and most patients retain functional vision. We found that longitudinal optic nerve lesions and optic nerve perineuritis were significantly associated with MOG + ON. These results corroborate findings of Chen et al. Among ON, Jarius et al. recommended testing MOG‐Ab only in cases of ODS, bilateral ON, severe ON, steroid dependent symptoms and frequent relapses. This expert advice is based on retrospective studies that are unable to evaluate the predictive value of such features. In our series, we validated predictive value of ODS and bilateral involvement. Their PPV is middling but their high NPV make them relevant. We could not validate the other features. Our study highlights the importance of determining ODS in cases of initial ON, in particular as this feature could be absent due to optic disc atrophy due to recurrence. Notably, the two MOG+ patients who did not have ODS during this study were recurrent ON; however, subsequent review of their records revealed ODS during their 1st episode. Testing MOG‐Ab only in the case of ODS or bilateral or recurrent ON would limit MOG‐Ab testing to 29 among 65 patients (45%) and would ensure that MOG + ON would not be missed.

Conclusion: Among ON episode, MOG‐Ab were found in 14% of cases. MOG + ON occurred without female preponderance and was significantly associated with ODS and/or bilateral ON. Testing MOG‐Ab only in patients presenting with ODS or bilateral or recurrent ON would limit MOG‐Ab tests to fewer than half of all patients without the risk of missing any MOG + ON cases.