The Incidence and Prevalence of Neuromyelitis Optica

Abstract

Interest in neuromyelitis optica (NMO) has increased substantially over the last few years, but it is not known whether NMO has the same geographic and temporal variations in disease risk as multiple sclerosis (MS). We aimed to evaluate the worldwide incidence and prevalence of NMO through a systematic review of published peer-reviewed studies. We performed a search of the English-language literature using MEDLINE and EMBASE from January 1985 to March 2012. Search terms included "neuromyelitis optica," "Devic's," "opticospinal," "incidence," "prevalence," and "epidemiology."We assessed study quality using a standardized instrument. A total of five studies met the inclusion criteria. Three of the studies were from North America, and all studies were published between 2005 and 2012. All studies were of good quality, but only one study reported standardized rates, and subgroup-specific estimates were rarely reported. The incidence of NMO per 100,000 population ranged from 0.053 to 0.40, while the prevalence per 100,000 population ranged from 0.52 to 4.4. Heterogeneity was high among the incidence (I 2 = 68.0%) and prevalence studies (I 2 = 94.0%). This review highlights the limited knowledge regarding the epidemiology of NMO and the importance of obtaining estimates standardized to common populations to enhance comparability of studies from different jurisdictions. Future studies would also benefit from reporting age-, sex-, and race-or ethnicity-specific estimates. Int J MS Care. 2013;15:113-118. Like multiple sclerosis (MS), neuromyelitis optica (NMO) is a demyelinating disease of the central nervous system, but it differs from MS in important ways. NMO is a monophasic or relapsing-remitting disorder predominantly characterized by optic neuritis and transverse myelitis.1 Although it may be misdiagnosed as MS because of its overlapping clinical symptoms of optic neuritis and transverse myelitis, it can usually be distinguished from MS on the basis of several features, including transverse myelitis presenting with longitudinally extensive spinal cord lesions; a tendency to spare the brain, but when the brain is affected, the presence of magnetic resonance imaging (MRI) lesions atypical for MS 2 ; and frequent association with seropositivity for NMO IgG (IgG antibody to aquaporin-4).3 It appears to overlap with the "opticospinal MS" described in Asia, which is also characterized by predominant involvement of the optic nerves and spinal cord, although whether they represent the same entity is somewhat controversial. 3,4 In clinic-based studies, a relative excess of nonwhites has been consistently recognized among patients with NMO compared with MS, 5,6 suggesting that the geographic distribution of NMO as measured by incidence and prevalence may differ from that of MS. Despite rapidly growing interest, the epidemiology of NMO remains poorly characterized. We aimed to evaluate the worldwide incidence and prevalence of NMO through a systematic review.

Low Levels of Vitamin D in Neuromyelitis Optica Spectrum Disorder: Association with Disease Disability

“…In particular, the prevalence of MS is higher in high-latitude regions, where sunshine, required for the synthesis of vitamin D, is lacking, which suggests that vitamin D deficiency could be a risk for MS. By contrast, geographic variations were not observed in the incidence or prevalence of NMO between regions [37]. In addition, pathologic studies do not indicate that antibodies to specific membrane targets like AQP4 are primarily involved in the immunopathologic process of MS, as opposed to NMO [38], [39].…”

Neuromyelitis optica and the evolving spectrum of autoimmune aquaporin‐4 channelopathies: a decade later

“…Incidence ranges from 0.053 to 0.40 per 100,000 people. 19 The prevalence ranges from 0.3 to 4.4 per 100,000. Asian and African-American populations are disproportionately affected, which contrasts with white populations where MS is about 40 times more common than NMO.…”

Development of a patient‐centred conceptual framework of health‐related quality of life in neuromyelitis optica: a qualitative study

“…44 The higher proportion of women in this study is potentially attributable to the gender ratio in NMO (females : males; 5 : 1). 2 Although in some countries NMO has a higher incidence in African American and Asian populations, 45 the clinical population in which this sample was recruited from has been previously found to be 88% Caucasian. 2 The majority of participants who opted in to this study were White British, mirroring the demographic of the local clinical population and limiting the conclusions that can be drawn about HRQoL in people with NMO of other ethnic backgrounds.…”