TRUE-MOGAD Score: A Novel Scoring System to Identify MOGAD Among Positive MOG-IgG Test Results.

OBJECTIVES: Myelin oligodendrocyte glycoprotein (MOG) antibodies (MOG-IgG) are a biomarker of MOG antibody-associated disease (MOGAD). However, false positives remain common. We aimed to develop a scoring tool to guide interpretation. METHODS: Observational study of MOG-IgG-positive patients at Mayo Clinic (May 2022-December 2024). The primary outcome was fulfillment of 2023-MOGAD diagnostic criteria. Predictive variables were identified using logistic regression, and scoring systems were derived and evaluated using receiver operating characteristic analysis. Internal (n = 92) and external (Johns Hopkins, n = 117) validation was performed. RESULTS: Of 215 MOG-IgG positive patients, 144 were true positive per 2023-MOGAD diagnostic criteria (positive predictive value, 67.0%). The DISCUSSION: The TRUE-MOGAD score is a practical tool that accurately identifies MOGAD among positive MOG-IgG test results and may guide diagnostic and therapeutic decisions in clinical practice. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that a TRUE-MOGAD score of 2 or more accurately predicts MOGAD in patients with MOG-IgG titers of 1:20 or higher using the assay described.