Introduction of international consensus criteria (2015 IPND criteria) for neuromyelitis optica spectrum disorders (NMOSDs) has improved diagnostic accuracy for aquaporin 4 (AQP4)-IgG-associated and seronegative NMOSDs. This study aimed to review relevant publications related to the incidence and prevalence of NMOSDs and provide an updated review of the global epidemiology of NMOSDs in the light of new diagnostic criteria. A comprehensive literature search was performed from January 2015 to June 2021 by using appropriate keywords in PubMed, Scopus, and Web of Science. Relevant papers that fulfilled inclusion criteria were shortlisted and reviewed. Twenty-one papers were selected for this review. Incidence of NMOSDs was 0.04-0.25/100,000 in predominantly white and 0.34-1.31/100,000 in nonwhite populations. Prevalence was 0.70-1.91/100,000 in white and 0.86-4.52/100,000 in nonwhite populations. The 2015 IPND criteria significantly improved the incidence and prevalence rates for NMOSDs when compared to the Wingerchuk 2006 criteria. Incidence of MOG-IgG-associated NMOSDs was 0.12-0.13/100,000, with prevalence in children 0.03-1.4/100,000 and in adults 0.65-2/100,000. In this systematic review, studies that used uniform diagnostic criteria and confirmed cases after testing for AQP4-IgG were included. The prevalence of NMOSDs was estimated to be <5/100,000 globally. A clear bias was seen in favor of nonwhite and indigenous populations. This review highlights the need for prospective population-based epidemiological studies and the importance of surveys in nonwhite populations around the globe.
Keywords: Epidemiology; IPND criteria; incidence; neuromyelitis optica spectrum disorders; prevalence.