MOGAD in South Wales: Diagnostic Evolution and Disease Epidemiology

BACKGROUND: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a rare antibody-mediated inflammatory demyelinating disorder. In 2023, new international consensus diagnostic criteria were agreed. This study uses these criteria to describe epidemiological features of MOGAD in a population-based cohort of patients from south Wales, UK. METHODS: Retrospective review of case notes on all positive MOG-IgG results in South Wales between 01 January 2011 and 30 June 2024 was undertaken, 2023 diagnostic criteria applied and standardised clinical features recorded. Paediatric MOGAD was defined as age at onset < 16 years and adult MOGAD ≥ 16 years. The incidence period was between 01 January 2015 and 31 December 2023. RESULTS: Seventy-six prevalent cases were identified: 53 adults and 23 children. Minimum estimated prevalence of MOGAD in south Wales on 30 June 2024 was 76/1,974,110 population (3.85/100,000 population; 95% CI 3.03-4.82). Paediatric prevalence was 6.59/100,000 population (95% CI 4.18-9.89) and adult prevalence 3.26/100,000 population (95% CI 2.44-4.27). Sex ratio was almost equal in males and females. The most frequent presentations were optic neuritis in adults (62.3%) and ADEM in children (34.8%); 64.5% had a monophasic disease course over a median follow-up of 38 months (IQR 13-63). Mean annual incidence was 3.39 (95% CI 2.58-4.39) per million population. CONCLUSIONS: This regional study provides updated prevalence and incidence rates for MOGAD since the introduction of 2023 diagnostic criteria in a stable south Wales, UK population.