Application of the 2015 neuromyelitis optica spectrum disorders diagnostic criteria in a cohort of Chinese patients.

Background: There is no validation study evaluating 2015 International Panel for neuromyelitis optica (NMO) spectrum disorders (NMOSD) diagnosis (IPND) criteria in Chinese population. The association of myelin oligodendrocyte glycoprotein-immunoglobulin-G (MOG-IgG) with NMOSD was also not investigated in previous validation studies. Hence, we aimed to validate the 2015 NMOSD criteria in a cohort of Chinese patients, and to assess the association between MOG-IgG and NMOSD.

Methods: We applied both the 2006 NMO and the 2015 NMOSD diagnostic criteria to all suspected NMOSD inpatients at the Department of Neurology of Chinese PLA general hospital diagnosed between 2016 and 2019. Demographics, core clinical features, AQP4-IgG and MOG-IgG status were retrieved and analyzed.

Results: A total of 185 patients fulfilling the 2015 NMOSD criteria (154 AQP4-IgG positive, 23 AQP4-IgG negative, 8 AQP4-IgG status unknown) were included, whereas only 43.2% (80/185) fulfilled the 2006 NMO criteria. After assuming all the NMOSD patients with unknown AQP4-IgG status, 69.7% (129/185) still fulfilled the 2015 NMOSD criteria, whereas only 39.5% (73/185) met the 2006 NMO diagnostic criteria (p < 0.001). Most NMOSD patients (n = 55, 29.7%) disqualified because of not meeting the criterion of dissemination in space. The median time to diagnosis was 3 months (129 patients, range: 1-145 months) by the 2015 NMOSD criteria and 10 months (73 patients, range: 1-185 months) by the 2006 NMO criteria (log rank test: p = 0.002). Positive MOG-IgG was found in 28.6% (4/14) of the AQP4-IgG negative and 2.8% (1/36) of the AQP4-IgG positive NMOSD patients (p = 0.006). NMOSD with MOG-IgG was more frequently in male (3/1 vs. 2/33, p = 0.004) and with younger onset age (24.8 vs. 41.4, p = 0.045), in comparison with NMOSD with AQP4-IgG.

Conclusion: The 2015 NMOSD criteria markedly improved the diagnostic rate and reduced the time taken to diagnosis in a cohort of Chinese patients, even with unknown AQP4-IgG status, in comparison with the 2006 NMO criteria. Not meeting the criterion of dissemination in space, that is, having isolated core clinical feature, was the main factor precluding NMOSD diagnosis under assumption of unknown AQP4-IgG status. NMOSD with MOG-IgG was not uncommon in NMOSD without AQP4-IgG and had unique features regarding gender predominance and onset age.