Live-Cell-Based Assay Outperforms Fixed Assay in MOGAD Diagnosis: A Retrospective Validation Against the 2023 International Criteria

<b>Background and Objective</b>: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a significant component of demyelinating diseases in pediatric populations. Recently, diagnostic criteria for MOGAD were established. This study aims to evaluate and compare the diagnostic efficacy of the fixed-cell-based assay (Fixed-CBA) and the live cell-based assay (Live-CBA) in patients who meet the 2023 clinical diagnostic criteria for MOGAD. <b>Methods</b>: This retrospective study included patients suspected of having MOGAD who were enrolled between June 2023 and June 2024. Patients were selected based on the "core clinical demyelinating events" outlined in the 2023 proposed criteria of the International MOGAD Panel. Patients with multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD) with aquaporin-4 antibody-positive (AQP4-Abs-positive), and non-central nervous system (non-CNS) inflammatory diseases were chosen as controls. Serum samples were simultaneously tested for MOG-Abs using Fixed-CBA and Live-CBA. <b>Results</b>: A total of 86 patients were enrolled in the study: 52 in the suspected MOGAD group and 34 in the control group. Out of these patients studied, 16 presented with optic neuritis (ON), 5 with myelitis, 8 with acute disseminated encephalomyelitis (ADEM), and 7 with cortical encephalitis. Sixteen patients could not be classified by clinical phenotype. The highest MOG-Ab positivity rate was among patients with cortical encephalitis [85.7% (Live-CBA)/71.4% (Fixed-CBA)]. Both assays identified 22 positive samples, with Fixed-CBA and Live-CBA sensitivities at 44.2% and 55.8%, respectively, and a specificity of 97%. Of the patients suspected of having MOGAD, 19 cases were confirmed using the Fixed-CBA, while 28 cases were confirmed using the Live-CBA. This resulted in an upgrade in diagnostic classification for nine cases. This led to a diagnostic reclassification in nine cases. <b>Conclusions</b>: Both the Fixed-CBA and Live-CBA were associated with higher sensitivity for patients selected based on the 2023 MOGAD clinical diagnostic criteria. The Live-CBA exhibited an 11.6% increase in sensitivity, contributing to a 17.3% (9/52) enhancement in clinical diagnostic accuracy.