The prevalence of neuromyelitis optica in South East Wales

Background and purpose: Neuromyeltis optica (NMO) is a neuroinflammatory disorder considered rare in Caucasian populations. However, accurate population-based epidemiological data for NMO and NMO spectrum disorder (NMO-SD) from Western populations employing validated diagnostic criteria remain limited. We sought therefore to estimate the prevalence and clinical features of NMO in a north European Caucasian population in South East Wales. Methods: Patients were identified by a comprehensive, multistage ascertainment strategy employing a regional neuroinflammatory disease register, hospital diagnostic databases personal physician referrals and regional requests for anti-aquaporin-4 antibodies (anti-AQP4). Results: Fourteen Caucasian patients (11 patients with NMO and three with NMO-SD) were identified in a population of 712 572 (19.6/million; 95% CIs: 12.2-29.7). There was an excess of females (female: male 12: 2), 11/14 were anti-AQP4 positive and 5/14 had disease onset under the age of 20 years. Conclusion: This study suggests that NMO and related spectrum disorders are at least as frequent in Northern European populations as in non-Caucasian populations and that the demographic profile of prevalent patients differs from clinic-based cohorts.