The prevalence of multiple sclerosis and other neurological diseases in Japan

The incidence and prevalence, diagnosis, and treatment of multiple sclerosis in China: a narrative review

In 2018, the first list of rare diseases was published by the National Health Council of China, and multiple sclerosis (MS) was included in this list. Since then, the Chinese government and neurologists have made efforts to improve the clinical outcomes of patients with MS. During last few years, the incidence of MS in China was also investigated. The early and accurate diagnosis of MS was improved due to the application and promotion of magnetic resonance imaging and new diagnosis criteria. The market for and medical insurance access to disease-modifying therapies (DMTs) has been greatly accelerated, which has provided more treatment options and improved clinical outcomes for patients with MS, as well as reduced treatment cost. The pattern of MS in China is gradually changing, from delayed to early diagnosis, and from no treatment to treatment with DMTs during remission. This narrative review aimed to summarize an update to the status of MS in China, including incidence and prevalence, diagnosis, and available treatments. This would help to better understand the diagnosis and treatment gap between mainland China and other Asian regions, demonstrating the necessity of accurate diagnosis and optimized treatment of MS in China.

Global prevalence of myasthenia gravis and the effectiveness of common drugs in its treatment: a systematic review and meta-analysis

BACKGROUND

Myasthenia gravis is a neuromuscular autoimmune disorder characterized by weakness and disability in the voluntary muscles. There have been several preliminary studies on the epidemiology of myasthenia gravis in different parts of the world and the effectiveness of common drugs in its treatment, but there has been no comprehensive study of the efficacy of common drugs in the treatment of myasthenia gravis. Therefore, this study aimed to determine the epidemiology of myasthenia gravis globally and the effectiveness of common drugs in its treatment using systematic review and meta-analysis.

METHODS

Research studies were extracted from IranDoc, MagIran, IranMedex, SID, ScienceDirect, Web of Sciences (WoS), ProQuest, Medline (PubMed), Scopus and Google Scholar based on Cochran's seven-step guidelines using existing keywords extracted in MeSH browser. The I2 test was used to calculate the heterogeneity of studies, and Begg and Mazumdar rank correlation tests were used to assess publication bias. Data were analyzed using Comprehensive Meta-Analysis software (Version 2).

RESULTS

In the search for descriptive studies based on the research question, 7374 articles were found. After deleting articles unrelated to the research question, finally, 63 articles with a sample size of 1,206,961,907 people were included in the meta-analysis. The prevalence of MG worldwide was estimated to be 12.4 people (95% CI 10.6-14.5) per 100,000 population. For analytical studies on the effectiveness of common myasthenia gravis drugs, 4672 articles were found initially, and after removing articles unrelated to the research question, finally, 20 articles with a sample size of 643 people in the drug group and 619 people in the placebo group were included in the study. As a result of the combination of studies, the difference between the mean QMGS score index after taking Mycophenolate and Immunoglobulin or plasma exchange drugs in the group of patients showed a significant decrease of 1.4 ± 0.77 and 0.62 ± 0.28, respectively (P < 0.01).

CONCLUSION

The results of systematic review of drug evaluation in patients with myasthenia gravis showed that Mycophenolate and Immunoglobulin or plasma exchange drugs have positive effects in the treatment of MG. It also represents the positive effect of immunoglobulin or plasma exchange on reducing SFEMG index and QMGS index and the positive effect of Mycophenolate in reducing MG-ADL index, SFEMG and Anti-AChR antibodies index. In addition, based on a meta-analysis of the random-effect model, the overall prevalence of MG in the world is 12.4 people per 100,000 population, which indicates the urgent need for attention to this disease for prevention and treatment.

Historical vignette: Leonard T. Kurland, FACE (1921-2001), the rise of neuroepidemiology, and the Rochester Epidemiology Project

The creation of the field of neuroepidemiology was one of the two principal professional achievements of the American College of Epidemiology Fellow Leonard T. Kurland (1921-2001), the other being the establishment of the Rochester Project. In the former, Kurland established the role of the neuroepidemiologists in the development of the corpus of knowledge needed to control and prevent the occurrence of neurological conditions. Two examples of his endeavors in this regard were his work on the Guamanian focus of neurodegenerative diseases and his seminal investigations into the epidemiology of multiple sclerosis. He was also instrumental in the development of the Rochester, Minnesota community as a population laboratory within which epidemiologic investigations could be mounted. This pioneering achievement created a resource used by many generations of epidemiologists and clinicians to examine health and disease in the population.

Prevalence of muscular dystrophies: a systematic literature review

BACKGROUND

Determining the prevalence of neuromuscular disorders for the general population is important to identify the scope of burden on society and enable comparisons with other health conditions. This systematic review aims to identify and collate the findings of studies published between 1960 and 2013 on the prevalence of all types of muscular dystrophies.

SUMMARY

Relevant articles were identified through electronic database searches and manual searches of reference lists. There were 38 articles from across 19 countries that met the inclusion criteria. The total combined prevalence for all muscular dystrophies for studies classified as having a low risk of bias ranged between 19.8 and 25.1 per 100,000 person-years. Myotonic dystrophy (0.5-18.1 per 100,000), Duchenne muscular dystrophy (1.7-4.2) and facioscapulohumeral muscular dystrophy (3.2-4.6 per 100,000) were found to be the most common types of disorder. There was wide variation in study methodology, case ascertainment, and verification procedures and populations studied, all of which may contribute to the wide prevalence range, in addition to the likely variation in prevalence by country. Key Messages: Greater consistency in the conduct and reporting of neuroepidemiological studies is urgently needed to enable comparisons to be made between studies, countries, and over time.

A systematic review of population based epidemiological studies in Myasthenia Gravis

BACKGROUND

The aim was to collate all myasthenia gravis (MG) epidemiological studies including AChR MG and MuSK MG specific studies. To synthesize data on incidence rate (IR), prevalence rate (PR) and mortality rate (MR) of the condition and investigate the influence of environmental and technical factors on any trends or variation observed.

METHODS

Studies were identified using multiple sources and meta-analysis performed to calculate pooled estimates for IR, PR and MR.

RESULTS

55 studies performed between 1950 and 2007 were included, representing 1.7 billion population-years. For All MG estimated pooled IR (eIR): 5.3 per million person-years (C.I.:4.4, 6.1), range: 1.7 to 21.3; estimated pooled PR: 77.7 per million persons (C.I.:64.0, 94.3), range 15 to 179; MR range 0.1 to 0.9 per millions person-years. AChR MG eIR: 7.3 (C.I.:5.5, 7.8), range: 4.3 to 18.0; MuSK MG IR range: 0.1 to 0.32. However marked variation persisted between populations studied with similar methodology and in similar areas.

CONCLUSIONS

We report marked variation in observed frequencies of MG. We show evidence of increasing frequency of MG with year of study and improved study quality. This probably reflects improved case ascertainment. But other factors must also influence disease onset resulting in the observed variation in IR across geographically and genetically similar populations.

Myasthenia gravis: a population based epidemiological study in Cambridgeshire, England

OBJECTIVES

To perform a comprehensive survey of myasthenia gravis in the county of Cambridgeshire, England, establishing contemporary epidemiological data.

METHODS

Cases were ascertained from multiple sources. Prevalent patients were visited and assessed by means of a standardised questionnaire and examination complemented by review of medical case notes.

RESULTS

One hundred cases were identified in a population of 684000 (prevalence 15 per 100000 population, 95% confidence intervals (95% CIs) 12-18). Thirty eight new diagnoses were made over a five year period providing an incidence of 1.1/100000 population/year. The sex ratio was 2:1 F:M. After a mean follow up of 11.7 years, symptomatic disease was still restricted to ocular muscles in 25 patients. Thirty four of 100 patients underwent thymectomy a mean of 0.8 years after presentation, and a thymoma was present in 12. Highest remission rates were seen in patients presenting with generalised disease who underwent thymectomy but did not have a thymoma (27%). Cosegregation of an additional autoimmune disease occurred in 27 patients and in 24/49 (49%) women with onset<50 years of age.

CONCLUSIONS

This, the second highest reported prevalence for myasthenia, is likely to be the result of optimum case ascertainment, increased disease duration, application of complex diagnostic tests, and the impact of an aging population leading to a relative increase in the prevalence of ocular myasthenia.

Epidemiologic evidence for a changing natural history of myasthenia gravis

OBJECTIVE

To survey the epidemiologic literature for evidence of an increasing prevalence of myasthenia gravis (MG) over time, and to explore the reasons for the increase.

DATA SOURCES

We found population-based reports of the epidemiology of MG by searching bibliographic databases. We used MG, epidemiology, prevalence, incidence, and mortality as search terms.

STUDY SELECTION

We included population-based studies that reported the number of cases and the time period from which rates were calculated.

STATISTICAL METHODS

We performed a regression analysis of rates versus date of study, comparing the slopes of regression lines for prevalence, incidence, and mortality. We performed a second analysis grouping rates by decade of study and calculating a mean rate weighted by the size of the population studied. We calculated 95% confidence intervals for each rate.

RESULTS

We included 33 studies from 1950 through 1995. Prevalence and incidence rates increased over time, but the regression line for prevalence significantly exceeded that for incidence. Mortality rates declined slightly. The weighted means for prevalence rose significantly, but there was no significant change in incidence or mortality.

CONCLUSION

The prevalence of MG has increased over the past forty-five years, probably because patients with the disease have longer life spans owing to present-day treatment.