Neuromyelitis optica spectrum disorders in Algeria: A preliminary study in the region of Tizi Ouzou

Sex ratio and age of onset in AQP4 antibody-associated NMOSD: a review and meta-analysis

BACKGROUND

Aquaporin-4 (AQP4) antibody-associated neuromyelitis optica spectrum disorder (NMOSD) is an antibody-mediated inflammatory disease of the central nervous system. We have undertaken a systematic review and meta-analysis to ascertain the sex ratio and mean age of onset for AQP4 antibody associated NMOSD. We have also explored factors that impact on these demographic data.

METHODS

A systematic search of databases was conducted according to the PRISMA guidelines. Articles reporting sex distribution and age of onset for AQP4 antibody-associated NMSOD were reviewed. An initially inclusive approach involving exploration with regression meta-analysis was followed by an analysis of just AQP4 antibody positive cases.

RESULTS

A total of 528 articles were screened to yield 89 articles covering 19,415 individuals from 88 population samples. The female:male sex ratio was significantly influenced by the proportion of AQP4 antibody positive cases in the samples studied (p < 0.001). For AQP4 antibody-positive cases the overall estimate of the sex ratio was 8.89 (95% CI 7.78-10.15). For paediatric populations the estimate was 5.68 (95% CI 4.01-8.03) and for late-onset cases, it was 5.48 (95% CI 4.10-7.33). The mean age of onset was significantly associated with the mean life expectancy of the population sampled (p < 0.001). The mean age of onset for AQP4 antibody-positive cases in long-lived populations was 41.7 years versus 33.3 years in the remainder.

CONCLUSIONS

The female:male sex ratio and the mean age of onset of AQP4 antibody-associated NMOSD are significantly higher than MS. The sex ratio increases with the proportion of cases that are positive for AQP4 antibodies and the mean age of onset increases with population life expectancy.

Neuromyelitis Optica Spectrum Disorders in Africa: A Systematic Review

BACKGROUND AND OBJECTIVES

Neuromyelitis optica (NMO) is a CNS inflammatory disease that predominantly affects the optic nerves and the spinal cord. It is more frequent in Asian and African populations than in European ones. Data on epidemiology, clinical presentation, additional investigations, and treatment in the African continent are scarce. We aim to (1) collect and analyze published data on neuromyelitis optica spectrum disorder (NMOSD), (2) indicate challenges in the diagnosis and management, and (3) discuss opportunities for future research, education, and policy making, specifically on the African continent.

METHODS

A systematic review was performed in January 2021 with the search terms "Neuromyelitis optica and Africa," "Devic Disease and Africa," and "NMOSD and Africa." We included all study types except case reports, correspondence, or conference abstracts on NMO or NMOSD. Extracted data included study design, country, study period, demographic and clinical characteristics, results of paraclinical investigations, and outcome. Data analysis was performed with descriptive statistics.

RESULTS

We retrieved a total of 79 records, of which 19 were included. Ten of 54 African countries reported a total of 410 cases. Almost half of them were from North African countries. The mean age at diagnosis was 33 years (range 7-88 years), and 75% were female. Transverse myelitis followed by optic neuritis were the most frequent symptoms at the time of presentation. One hundred nineteen patients experienced at least 1 previous relapse, and 106 had a relapsing course after diagnosis. Relapses were treated with IV methylprednisolone. Azathioprine and steroids were used most often as maintenance treatments. Outcomes were rarely described.

DISCUSSION

The majority of studies on NMOSD from the African continent are retrospective, and most countries do not report any data. Our systemic review shows that data derived from patients living in Africa correspond well to what has been previously published in meta-analyses on patients of African ancestry with NMOSD who live outside of Africa, except for a younger age at onset and a lower proportion of females. We advocate for systematic data collection to adequately capture and monitor the burden of NMOSD, for expansion of research efforts and facilities to perform fundamental and clinical research, and for improved access to health care including diagnostics, treatments, and rehabilitation services for people affected by NMOSD in the African continent.

[Epidemiology of neuromyelitis optica spectrum disorder]

Neuromyelitis optica spectrum disorder (NMOSD) is a group of rare and mostly severe autoimmune demyelinating central nervous system disorders which prevalence is 0.7-1 per 100.000 population and incidence is 0.037-0.73 per 100.000 person-years. NMOSD may present as a combination of uni- or bilateral optic neuritis, transverse myelitis or lesions of brain stem and other brain regions. The symptoms are mostly relapsing (up to 97.5%) and progressive. Occurrence of relapses is associated with seropositivity for aquaporin-4 (up to 80% of NMOSD patients) and bears a less favorable prognosis (mortality up to 32%). Women seropositive for aquaporin 4 constitute 90% of NMOSD patients. Compared to other demyelinating disorders, NMOSD is characterized by late onset (mean age is about 39 years) and association with other autoimmune disorders, including systemic lupus erythematosus, myasthenia gravis and Sjogren's syndrome. A genetic predisposition was found among Blacks and Asians, with HLA-DRB1*03:01 gene associated with higher risk of NMOSD in Asians. The course of the disease tends to be more severe in Blacks. There are clusters of an increased incidence of NMOSD in the Carribeans and in the Far East. Continued increase of prevalence and incidence of NMOSD worldwide compels continued epidemiological research in order to provide early diagnosis and treatment for this disorder.

Comparisons of clinical phenotype, radiological and laboratory features, and therapy of neuromyelitis optica spectrum disorder by regions: update and challenges

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disease of the central nervous system (CNS) associated with autoantibody (ab) to aquaporin-4 (AQP4). There is obvious variation between regions and countries in the epidemiology, clinical features and management in NMOSD. Based on published population-based observation and cohort studies, the different clinical pattern of NMOSD has been seen in several geographical regions and some of these patients with NMOSD-like features do not fully meet the current diagnostic criteria, which is needed to consider the value of recently revised diagnostic criteria. At present, all treatments applied in NMOSD have made great progress, however, these treatments failed in AQP4 ab negative and refractory patients. Therefore, it is necessary to turn into an innovative idea and to open a new era of NMOSD treatment to develop novel and diverse targets and effective therapeutic drugs in NMOSD and to conduct the trails in large clinical samples and case-control studies to confirm their therapeutic effects on NMOSD in the future, which still remain a challenge.

Neuromyelitis optica spectrum disorder in Africa: What is the current state of knowledge?

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a chronic autoimmune inflammatory disease of the central nervous system, usually involving the optic nerve, brain, and spinal cord. While the disease is believed to be more common among individuals of African descent, the disease landscape across the continent has not been systematically explored. In this study, we carried out a systematic scoping review by synthesizing original studies on NMOSD from Africa.

METHODS

A comprehensive literature search of PubMed (MEDLINE), Scopus, Embase, and Web of Science databases with the search terms 'neuromyelitis optica' and 'Africa' was performed on June 17, 2020. Synthesis of the result was done using narrative analysis.

RESULT

Of the total 133 identified records, 14 eligible studies from Africa were included. Most of the studies were from North African countries (n = 8; 57%); predominantly retrospective descriptive (n = 8; 57%), or case series (n = 3; 21%); and published within the last two decades (n = 13; 93%). The total number of cases in the studies is 332, with a reported female to male ratio of 4:1 and an age range of 12-88 years at disease onset (average of <40 years in 50% of reports). Aquaporin-4 antibodies was tested in 214 cases and found in 61.7%. Three cases had Myelin Oligodendrocyte Glycoprotein antibody test with one of the cases testing positive and was associated with severe optic neuritis. Autoimmune disorders were reported in 23 out of 93 cases from three studies, while a few studies reported infectious disease associations. IV methylprednisolone was the rule during acute attacks from all the studies, while the choice of medication for maintenance varies, possibly depending on availability and cost.

CONCLUSION

The research landscape on NMOSD in Africa, though limited, provides significant insight into the epidemiology, etiology, and clinical characteristics of the disease. Gaps still exist in the knowledge of disease management. Further research focusing on the African context is needed to provide customized evidence-based care to patients with NMOSD.

Cases of neuromyelitis optica spectrum disorder from the East Africa region, highlighting challenges in diagnostics and healthcare access

Background

Neuromyelitis optica spectrum disorder (NMOSD) is an auto-immune disease of the central nervous system (CNS) associated with the IgG-antibody against aquaporin-4 (AQP4-IgG). There is little published epidemiology of NMOSD from sub-Saharan Africa (SSA).

Methods

We retrospectively collated NMOSD cases admitted to our tertiary regional neurology centre.

Results

We identified 11 cases (10 female, average age 30 years). 64% (7/11) were seropositive for AQP4-IgG, measured using indirect immunofluorescence. The remaining cases could either not afford tests, or had pathognomonic radiological features. 57% (4/7) of seropositive cases had concurrent/recent CNS infection. All patients were treated with high-dose intravenous methylprednisolone (IVMP), and 36% (4/11) also had plasma exchange. Only 55% (6/11) of the patients were seen by a neurologist at presentation: they had less relapses (1.3 vs 2.4), less diagnostic delay (2.3 vs 7.4 months), and were less disabled at the end of our review period. 10 cases were immunosuppressed long-term: 60% on mycophenolate, 30% azathioprine, and one on rituximab.

Conclusion

Our study is the largest case series of NMOSD from the East Africa region. Patients faced challenges of access to appropriate and affordable testing, and timely availability of a neurologist at onset, which had impacts on their functional outcomes. The majority of the seropositive cases had recent/concurrent CNS infections, suggesting triggered auto-immunity.

Epidemiology of Neuromyelitis Optica Spectrum Disorder and Its Prevalence and Incidence Worldwide

Neuromyelitis optica spectrum disorder (NMOSD) is an uncommon inflammatory disease of the central nervous system, manifesting clinically as optic neuritis, myelitis, and certain brain and brainstem syndromes. Cases clinically diagnosed as NMOSD may include aquaporin 4 (AQP4)-antibody-seropositive autoimmune astrocytopathic disease, myelin oligodendrocyte glycoprotein (MOG)-antibody-seropositive inflammatory demyelinating disease, and double-seronegative disease. AQP4-antibody disease has a high female-to-male ratio (up to 9:1), and its mean age at onset of ~40 years is later than that seen in multiple sclerosis. For MOG-antibody disease, its gender ratio is closer to 1:1, and it is more common in children than in adults. Its clinical phenotypes differ but overlap with those of AQP4-antibody disease and include acute disseminated encephalomyelitis, brainstem and cerebral cortical encephalitis, as well as optic neuritis and myelitis. Double-seronegative disease requires further research and clarification. Population-based studies over the past two decades report the prevalence and incidence of NMOSD in different populations worldwide. One relevant finding is the varying prevalence observed in different racial groups. Consistently, the prevalence of NMOSD among Whites is ~1/100,000 population, with an annual incidence of <1/million population. Among East Asians, the prevalence is higher, at ~3.5/100,000 population, while the prevalence in Blacks may be up to 10/100,000 population. For MOG-antibody disease, hospital-based studies largely do not observe any significant racial preponderance so far. This disorder comprises a significant proportion of NMOSD cases that are AQP4-antibody-seronegative. A recent Dutch nationwide study reported the annual incidence of MOG-antibody disease as 1.6/million population (adult: 1.3/million, children: 3.1/million). Clinical and radiological differences between AQP4-antibody and MOG-antibody associated diseases have led to interest in the revisions of NMOSD definition and expanded stratification based on detection of a specific autoantibody biomarker. More population-based studies in different geographical regions and racial groups will be useful to further inform the prevalence and incidence of NMOSD and their antibody-specific subgroups. Accessibility to AQP4-antibody and MOG-antibody testing, which is limited in many centers, is a challenge to overcome. Environmental and genetic studies will be useful accompaniments to identify other potential pathogenetic factors and specific biomarkers in NMOSD.

Comprehensive review of neuromyelitis optica and clinical characteristics of neuromyelitis optica patients in Puerto Rico

Neuromyelitis optica (NMO) is an immune-mediated inflammatory disorder of the central nervous system. It is characterized by concurrent inflammation and demyelination of the optic nerve (optic neuritis [ON]) and the spinal cord (myelitis). Multiple studies show variations in prevalence, clinical, and demographic features of NMO among different populations. In addition, ethnicity and race are known as important factors on disease phenotype and clinical outcomes. There are little data on information about NMO patients in underserved groups, including Puerto Rico (PR). In this research, we will provide a comprehensive overview of all aspects of NMO, including epidemiology, environmental risk factors, genetic factors, molecular mechanism, symptoms, comorbidities and clinical differentiation, diagnosis, treatment, its management, and prognosis. We will also evaluate the demographic features and clinical phenotype of NMO patients in PR. This will provide a better understanding of NMO and establish a basis of knowledge that can be used to improve care. Furthermore, this type of population-based study can distinguish the clinical features variation among NMO patients and will provide insight into the potential mechanisms that cause these variations.

Clinical characteristics of 153 Brazilian patients with neuromyelitis optica spectrum disorder (NMOSD)

BACKGROUND

The 2015 criteria for diagnosing neuromyelitis optica spectrum disorder (NMOSD) have encouraged several groups across the world to report on their patients using these criteria. The disease typically manifests with severe relapses of optic neuritis, longitudinally extensive myelitis and/or brainstem syndromes, often leading to severe disability. Some patients are seropositive for antibodies against aquaporin-4 (AQP4), others are positive for anti-myelin oligodendrocyte glycoprotein (MOG), while a few are negative for both biomarkers. The disease is complex, and only now are specific therapeutic clinical trials being carried out. The present study adds to the literature through detailed clinical data from 153 medical records of Brazilian patients.

METHODS

Retrospective assessment of medical records from nine specialized units in Brazil.

RESULTS

NMOSD was more prevalent in females (4.1:1), who had significantly fewer relapses than males (p = 0.007) but presented similar levels of disability over time. African ancestry was associated with higher levels of disability throughout the disease course (p < 0.001), although the number of relapses was similar to that observed in white patients. Concomitant autoimmune diseases were relatively rare in this population (6.5%). Positivity for anti-AQP4 antibodies was identified in 62% of the patients tested, while 3% presented anti-MOG antibodies. Anti-AQP4 antibodies were not associated to worse disease course. The last medical record showed that six patients had died and 13 were wheelchair-bound. Seventy percent of the patients did not respond to first-line therapy (azathioprine and/or corticosteroids), and five patients continued to relapse even after four different courses of treatment.

CONCLUSION

The present study adds to the reports from other countries presenting original data on Brazilian patients diagnosed with NMOSD according to the 2015 criteria.

Incidence and prevalence of NMOSD in Australia and New Zealand

OBJECTIVES

We have undertaken a clinic-based survey of neuromyelitis optica spectrum disorders (NMOSDs) in Australia and New Zealand to establish incidence and prevalence across the region and in populations of differing ancestry.

BACKGROUND

NMOSD is a recently defined demyelinating disease of the central nervous system (CNS). The incidence and prevalence of NMOSD in Australia and New Zealand has not been established.

METHODS

Centres managing patients with demyelinating disease of the CNS across Australia and New Zealand reported patients with clinical and laboratory features that were suspicious for NMOSD. Testing for aquaporin 4 antibodies was undertaken in all suspected cases. From this group, cases were identified who fulfilled the 2015 Wingerchuk diagnostic criteria for NMOSD. A capture-recapture methodology was used to estimate incidence and prevalence, based on additional laboratory identified cases.

RESULTS

NMOSD was confirmed in 81/170 (48%) cases referred. Capture-recapture analysis gave an adjusted incidence estimate of 0.37 (95% CI 0.35 to 0.39) per million per year and a prevalence estimate for NMOSD of 0.70 (95% CI 0.61 to 0.78) per 100 000. NMOSD was three times more common in the Asian population (1.57 (95% CI 1.15 to 1.98) per 100 000) compared with the remainder of the population (0.57 (95% CI 0.50 to 0.65) per 100 000). The latitudinal gradient evident in multiple sclerosis was not seen in NMOSD.

CONCLUSIONS

NMOSD incidence and prevalence in Australia and New Zealand are comparable with figures from other populations of largely European ancestry. We found NMOSD to be more common in the population with Asian ancestry.