Prevalence and Incidence of Neuromyelitis Optica Spectrum Disorder in Korea: Population Based Study

Epidemiology and Healthcare Utilization in Pediatric Multiple Sclerosis and Neuromyelitis Optica: A Nationwide Population-Based Study in South Korea (2016-2020)

Pediatric multiple sclerosis (MS) and neuromyelitis optica (NMO) are rare acquired demyelinating syndrome with limited epidemiological data available, particularly in non-Western setting. This study aimed to demonstrate the epidemiology of pediatric MS and NMO in South Korea and to analyze of healthcare utilization and economic burden associated with these conditions. Using a nationwide population-based database from the Korean Health Insurance Review and Assessment Service database, we identified pediatric cases (age < 20 years) of MS and NMO from 2016 to 2020. We analyzed incidence, prevalence, healthcare utilization and medical costs. The study found low age-standardized incidence and prevalence rates for pediatric MS and NMO in South Korea. There was a marked disparity in healthcare utilization between urban and rural areas. Most healthcare interactions occurred in tertiary hospitals in urban settings, particularly in Seoul. The study also highlighted the substantial economic burden associated with the management of rare diseases, with annual variability in medical costs. Pediatric MS and NMO are extremely rare in South Korea, with significant regional disparity in healthcare utilization. The findings emphasize the need for targeted healthcare policies to improve access and reduce disparities, particularly for chronic and rare diseases requiring specialized care.

Epidemiology of Chronic Inflammatory Demyelinating Polyneuropathy in South Korea: A Population-Based Study

BACKGROUND AND PURPOSE

We performed a population-based study to determine the prevalence and incidence of chronic inflammatory demyelinating polyneuropathy (CIDP) in South Korea using data from the Korean Health Insurance Review and Assessment Service (HIRA) database.

METHODS

Data recorded in the HIRA database between January 2016 and December 2020 were analyzed. The inclusion criteria in this study for patients with CIDP were a diagnostic code of G61.8 in the seventh and eighth revision of the Korean Standard Classification of Disease and a >3-month history of oral immunosuppressant use. The age-adjusted incidence rate and prevalence of CIDP in South Korea were also analyzed.

RESULTS

CIDP was newly diagnosed in 953 patients during the study period. The mean age at diagnosis was 58.36 years, and the male-to-female ratio was 1.74. The age-adjusted incidence rates were 0.22, 0.21, 0.23, 0.30, and 0.25 per 100,000 person-years in 2016, 2017, 2018, 2019, and 2020, respectively. The age-adjusted prevalence was estimated at 1.16 per 100,000 persons in 2020. Age and the Elixhauser Comorbidity Index were associated with the in-hospital mortality of patients with CIDP. Infection and cardiovascular disease (CVD) were also significantly associated with the in-hospital mortality of those patients. Acute-onset CIDP was initially diagnosed in an estimated 101 out of 953 patients with CIDP.

CONCLUSIONS

The prevalence and incidence rates of CIDP in South Korea were comparable between this nationwide cohort study and previous studies. Common comorbidities such as CVD and diabetes should be appropriately monitored in patients with CIDP to prevent a poor prognosis and socioeconomic burden.

The epidemiology and burden of neuromyelitis optica spectrum disorder, multiple sclerosis, and MOG antibody-associated disease in a province in Thailand: A population-based study

BACKGROUND

Central nervous system inflammatory demyelinating diseases (CNSIDDs) have notable interracial heterogeneity. The epidemiology of CNSIDDs in Thailand, a mainland Southeast Asian country, is unknown.

OBJECTIVES

To determine the cumulative incidence, point prevalence, and disease burden of neuromyelitis optica spectrum disorder (NMOSD) and other CNSIDDs in Thailand using population-based data of Chumphon.

METHODS

Searching for CNSIDD patients at a public secondary care hospital in Chumphon, the only neurology center in the province, from January 2016 to December 2021 was implemented using relevant ICD-10-CM codes. All diagnoses were individually ascertained by a retrospective chart review. Cumulative incidence, point prevalence, attack rate, mortality rate, and disability-adjusted life years (DALYs) were calculated.

RESULTS

Aquaporin 4-IgG-positive NMOSD was the most prevalent CNSIDD in the Thai population at 3.08 (1.76-5.38) per 100,000 persons. The prevalence of multiple sclerosis (MS) followed at 0.77 (0.26-2.26) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) at 0.51(0.14-1.87) per 100,000 adults. In the pediatric population, the incidence of acute disseminated encephalomyelitis was 0.28 (0.08-1.02) per 100,000 persons/year. Among other idiopathic demyelinating diseases, idiopathic optic neuritis had the highest incidence at 0.58 (0.24-0.92) per 100,000 persons/year, followed by acute transverse myelitis at 0.44 (0.14-0.74). Idiopathic demyelinating brainstem syndrome was also observed at 0.04 (0.01-0.25) per 100,000 persons/year. Although most had a fair recovery, disability was worst among NMOSD patients with DALYs of 3.61 (3.00-4.36) years per 100,000 persons. Mortality rate was the highest in NMOSD as well.

CONCLUSION

CNSIDDs are rare diseases in Thailand. The prevalence is comparable to that of East Asian populations. A nationwide CNSIDDs registry would better elaborate the epidemiology of these diseases.

Results of a Survey on Diagnostic Procedures and Treatment Choices for Neuromyelitis Optica Spectrum Disorder in Korea: Beyond the Context of Current Clinical Guidelines

Background and Purpose

Neuromyelitis optica spectrum disorder (NMOSD) is a rare demyelinating disease of the central nervous system (CNS). We investigated the medical behaviors of experts in Korea when they are diagnosing and treating NMOSD.

Methods

An anonymous questionnaire on the diagnosis and treatment of NMOSD was distributed to experts in CNS demyelinating diseases.

Results

Most respondents used the 2015 diagnostic criteria for NMOSD and applied a cerebrospinal fluid examination, magnetic resonance imaging (MRI) of the brain and spine, and anti-aquaporin-4 antibody testing to all suspected cases of NMOSD. All respondents prescribed steroid pulse therapy as an first-line therapy in the acute phase of NMOSD, and 67% prescribed azathioprine for maintenance therapy in NMOSD. However, details regarding monitoring, the tapering period of oral steroids, second-line therapy use in refractory cases, management during pregnancy, and schedule of follow-up MRI differed according to the circumstances of individual patients. We analyzed the differences in response rates between two groups of respondents according to the annual number of NMOSD patients that they treated. The group that had been treating ≥10 NMOSD patients annually preferred rituximab more often as the second-line therapy (p=0.011) and had more experience with rituximab treatment (p=0.015) compared with the group that had been treating <10 NMOSD patients.

Conclusions

This study has revealed that NMOSD experts in Korea principally follow the available treatment guidelines. However, the differences in specific clinical practices applied to uncertain cases that have been revealed will need to be investigated further in order to formulate suitable recommendations.

Evaluating the Economic Burden of Relapses in Neuromyelitis Optica Spectrum Disorder: A Real-World Analysis Using German Claims Data

Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease of the central nervous system which causes recurrent relapses, resulting in blindness, paralysis, and spinal cord damage. This study sought to explore the real-world burden, treatment, and cost of NMOSD in Germany using claims data.

Methods

Our study consisted of a retrospective analysis of two anonymized health insurance datasets covering around 9 million patients in Germany from 01/01/2013 to 31/12/2019. NMOSD patients were identified using inpatient and outpatient International Classification of Diseases, Tenth Revision (ICD-10) diagnoses of neuromyelitis optica (NMO; G36.0) and relevant symptom codes. Active periods of disease were identified based on relapse events (including hospitalizations and acute treatment); healthcare resource utilization (HCRU) and direct costs were allocated to active and inactive periods based on treatment dates. Propensity score matching was used to compare HCRU and cost outcomes among patients with and without NMOSD.

Results

Overall, 130 patients were identified as having NMOSD (mean age: 46.84 years; 58% female). NMOSD patients recorded 16.52 active and 348.48 inactive days per patient year (PPY). HCRU and associated costs were approximately tenfold higher during active periods than during inactive periods, with the largest share of the cost difference driven by hospitalizations (€6424.09/€259.10 per active/inactive month) and outpatient drug prescriptions (€412.83/€271.58). Direct healthcare costs incurred by patients with NMOSD (€12,913.28 PPY) were approximately threefold higher than those incurred by patients without NMOSD (€4667.66 PPY). Costs of hospitalization (€6448.32/€1937.64 PPY) and outpatient prescriptions (€3335.67/€1037.64 PPY) contributed most strongly to the difference.

Conclusion

Patients with NMOSD consume substantial healthcare resources and incur heavy costs during active disease phases. This study captured direct measurable healthcare costs and likely underestimates the real societal/emotional burden on patients and their families. Nevertheless, prevention of acute relapses represents one compelling strategy to minimize the economic burden of NMOSD in Germany.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00311-x.

[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.

Prevalence of neuromyelitis optica spectrum disorder in Belo Horizonte, Southeast Brazil

BACKGROUND

Studies on the prevalence of neuromyelitis optica spectrum disorder (NMOSD) are still scarce. The aim of the current study was to determine the prevalence rate of NMOSD in Belo Horizonte, southeast Brazil, where the prevalence rate of multiple sclerosis (MS) has already been established.

METHODS

For this observational study, eligible patients had to meet the 2015 International Panel for Neuromyelitis Optica Diagnosis, be seen at the study center between January 2000 and February 2019 and live in Belo Horizonte. The prevalence rate of NMOSD was estimated based on the number of MS and NMOSD patients seen at same Center during the same period, and the previously established prevalence of MS in Belo Horizonte.

RESULTS

During the study period, there were 69 patients with NMOSD, 60 (87.0%) of whom were females, and 44 (63.8%) non-whites. The median age at disease onset was 36.7 (4-72) years, the mean EDSS score 4.78±2.36, and the mean ARR 0.57±0.43. Anti-aquaporin-4 immunoglobulin testing was available for 61 (88.4%) patients, of whom 41 (67.2%) had a positive result. During the same period, 280 MS patients were seen. Considering the local known prevalence rate of MS of 18.1/100,000 inhabitants, the estimated NMOSD prevalence rate in Belo Horizonte was 4.52/100,000 (95% CI 3.72-5.43) inhabitants.

CONCLUSION

The prevalence rate of NMOSD in Belo Horizonte is high as compared with those found in most of the studies reported to date.

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.