Investigators found that frequency of MOG-Ab associated NMOSD was not significantly different between Asian and Caucasian populations despite the prevalence of NMOSD in Asian regions.
A total of 14 studies, conducted between 2012 and 2020, were included in the review, done by Xindi Li, MD, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, and colleagues. When analyzing the number of MOG-Ab positive patients, investigators found that 9.3% of NMO/NMOSD patients were MOG-Ab positive (95% CI, 7.9-10.8; I2 = 13.1%).1
When evaluating the occurrence of MOG-Ab in patients with AQP4-Ab seronegative NMOSD, 32.5% were positive (95% CI, 25.7-39.3; I2 = 45.8%). This data waws found to be significantly influenced by differences between diagnostic criteria between 2006/2007 and 2015 (P = .002; R2 = 1), but relatively uninfluenced by study type (P = .90) and region (P = .96). When using only International Panel for NMO Diagnosis (IPND) 2015 NMOSD criteria, the subset of AQP4-Ab seronegative NMOSD patients with MOG-Abs reached up to 41.6% (95% CI, 35.1-48.2; I2 = 0.0%).
“In contrast with the 2006 NMO criteria, the term NMOSD was proposed in order to cover a wider clinical spectrum than previously accommodated by NMO criteria, notably adding MRI requirements including optic neuritis lesions extending over [one-half] the optic nerve length or involving optic chiasm, LETM lesions extending over three contiguous segments, and periependymal brain lesion,” Li et al wrote.1 “Consequently, only 49% of the panel-defined NMOSD were also diagnosed by 2006 Wingerchuk NMO criteria, while 97% were correctly identified by the IPND 2015 NMOSD criteria in a study of pediatric patients.”1,2
Investigators further evaluated the frequency of MOG-Ab associated NMOSD between Asian and European populations, finding no significant differences (31.0% versus 34.3%, P >.05). For the Asian studies, all patients with MOG-Ab–associated NMOSD were non-Caucasian, with an overall occurrence rate of MOG-Ab of 10.6% (95% CI, 7.2-14.0; I2 = 55.3%). Within the subpopulation of AQP4-Ab seronegative NMO/NMOSD, the rate was 31.0% (95% CI, 22.1-39.9, I2 = 54.1%). Studies conducted in Europe evaluated total NMO/NMOSD cases, which had a pooled MOG-Ab rate of 9.5% (95% CI, 6.9–12.1; I2 = 0.0%). The subpopulation had a MOG-Ab rate of 34.3% (95% CI, 21.9-46.7; I2 = 51.9%).
Limitations were also present, as a restricted sample number rendered investigators unable to evaluate all the factors contributing to heterogeneity. There was also potential for study bias in patient enrollment, difference in study objectives, and different conditions of centers for detecting antibodies.
“We emphasize the importance of MOG-Ab screening in AQP4-Ab seronegative NMOSD cases, and suggest that a revision of the criteria for AQP4-Ab negative NMOSD will facilitate distinction of this condition from MOG-AD, enabling accurate diagnosis and treatment recommendations for these immune-mediated diseases,” Li et al wrote.
An additional study, conducted by Edgar Carnero Contentti, MD, MSc, neuroimmunology unit, department of neuroscience, Hospital Alemán, Buenos Aires, Argentina, et al, contributed additional data from the Latin American (LATAM) population, which was not included in the original study from Li et al.
Investigators compiled a report, concluding that 7%-27% of AQP4-Ab-negative NMOSD patients in LATAM were positive for MOG-Ab.3 The lack of MOG-Ab test availability within this population was noted by investigators, as well as the only reports being available from Argentina and Brazil. Future research is necessary to understand how this condition can be evaluated, managed and treated within the LATAM population.