Hospital and healthcare insurance system record-based epidemiological study of myasthenia gravis in southern and northern China

Aging and infectious diseases in myasthenia gravis

Over the past 120 years, mortality associated with myasthenia gravis (MG) has steadily decreased while the incidence of MG has increased. While mortality due to MG has been ≤5 % for at least the past 25 years, the prevalence of MG has increased. This increase in prevalence of MG may be due, in part, to improvements in diagnostics but also to an aging global population and immunosenescence as the largest increases in MG prevalence have been in patients ≥65 years old. In fact, a "very late-onset" subtype of MG has been proposed for patients diagnosed at or after age 65 years. These patients are predominantly anti-AChR antibody positive and thymoma negative. Preferred therapeutic options differ based on age at MG onset. Immunosenescence may play a role not only in MG etiology but also in the increased susceptibility of MG patients to infection. Immunosuppressive effects of MG therapies can also increase vulnerability to infection. Despite the improvements in MG treatment, mortality in MG patients remains higher than in the non-MG population. This is partly due to increased vulnerability to infection but also due to infection acting as a precipitating factor for MG exacerbation or crisis. The increased infection risk inherent with MG and the increased risk resulting from some therapies calls for increased diligence in monitoring and treating infections in MG patients.

Prevalence, Incidence, and Mortality of Myasthenia Gravis and Myasthenic Syndromes: A Systematic Review

INTRODUCTION

No systematic reviews were published in the last years investigating epidemiological data, involving myasthenia gravis (MG) and related myasthenic syndromes. This systematic review aimed to estimate the prevalence, incidence, and mortality of all MG types and myasthenic syndromes worldwide.

METHODS

All literature published up to February 2024 was retrieved by searching the databases "Medline," "Embase," "ISI Web of Science" and "CINAHL" using the following search terms: (epidemiolog* OR frequency OR prevalence OR incidence OR mortality) AND (myasth* OR "anti-acetylcholine receptor antibody" OR "AChR" OR "MuSK" OR "anti-muscle specific kinase antibody" OR "LRP4" OR "seronegative MG").

RESULTS

A total of 94 studies, performed between 1952 and 2022, were included. Prevalence of MG ranged from 20 to 475 cases per million, with a mean prevalence of 173.3 (95% confidence interval [CI]: 129.7-215.5) cases per million and a median prevalence of 129.6 cases per million. Incidence rates ranged from 2.3 to 61.3 cases per million person-years, with a mean incidence of 15.7 (95% CI: 11.5-19.9) and a median of 13.3 cases. Mortality rates showed a mean of 1.4 (95% CI: 0.8-2.1) cases per million person-years. Acetylcholine receptor (AChR)-MG was the clinical subtype more frequent in terms of prevalence and incidence.

DISCUSSION

The prevalence and incidence of MG have significantly increased over the last years worldwide, probably due to the improvement of epidemiological methodologies and current advances in diagnosis. However, we observed a significant variation in frequencies of MG between and within countries because of methodological biases and complex heterogeneity of the disease characterized by several phenotypes and different clinical responses.

Epidemiology, Patient Characteristics, and Treatment Patterns of Myasthenia Gravis in Taiwan: A Population-Based Study

INTRODUCTION

Myasthenia gravis (MG) is a chronic neuromuscular disease leading to significant disease burden. This study aimed to investigate the epidemiology of MG in Taiwan.

METHODS

A retrospective study was conducted using the Taiwan National Health Insurance Research Database. Prevalent patients with MG diagnosis (either ocular or generalized MG) from 2013 to 2019 were identified, and 2813 patients with initial MG diagnosis from 2014 to 2019 were further defined as the incident cohort. Patient characteristics, treatment patterns, and the occurrence of MG-related events were analyzed.

RESULTS

The number of prevalent patients with MG increased from 4476 in 2013 to 5752 in 2019, with the prevalence rate increasing from 19 to 24 per 100,000 population. The incidence rate also slightly increased from 1.9 to 2.3 per 100,000 population during the study period. Almost all incident patients (99%, n = 2791) received MG-related treatment during the follow-up period. Among 1876 patients who received monotherapy as their initial treatment in the outpatient setting, the mean time from the index date to initial treatment was 48.8 (standard deviation 164.3) days, and most patients received acetylcholinesterase inhibitors (88.5%, n = 1661) as their initial treatment. During the first year after the index date, 133 (4.7%) incident patients experienced their first myasthenic crisis, and 96.2% of these events occurred within 3 months.

CONCLUSION

The prevalence of MG increased steadily in Taiwan, and the treatment of patients with MG was consistent with guidelines. Despite a high treatment rate, patients still experienced MG-related events, highlighting the limitation of current treatments and emphasizing the need for early intervention and novel treatment approaches.

Incidence and prevalence of myasthenia gravis in the United States: A claims-based analysis

INTRODUCTION/AIMS

Myasthenia gravis (MG) is a rare neuromuscular disorder with geographically variable prevalence and incidence rates. A global trend of increasing prevalence of MG has been observed in the last few decades, and this study aimed to assess the current prevalence and incidence rates of MG in the United States.

METHODS

Data were extracted from the Clarivate Real-World Data Repository (2016-2021), a US claims and electronic health records database. The prevalence and incidence of MG were calculated for the year 2021 for males and females who were <2, 2-5, 6-11, 12-17, 18-49, 50-64, and ≥65 years of age, using population estimates from the US Census.

RESULTS

The diagnosed prevalence and incidence of MG in the United States in 2021 were calculated to be 37.0 per 100,000 persons and 3.1 per 100,000 persons, respectively. While the incidence and prevalence of MG increased with age in both men and women, higher prevalence and incidence of MG were observed in younger women (<50 years) compared with men of matching age, and in older men (≥65 years) compared with women of the same age group.

DISCUSSION

The updated prevalence and incidence of MG in the United States in 2021 are higher than previous reports from the 1980s and early 2000s, following a global trend of increased prevalence and incidence for this disorder in the last few decades.

Diagnosis and therapy of myasthenia gravis-the patients' perspective: a cross-sectional study

The survey aimed to explore patients' perspectives with myasthenia gravis (MG) toward the diagnosis made and the therapy used to treat MG. The survey was conducted with a quantitative method, using the CAWI technique. A total of 321 people participated in the survey. More than half of the respondents (56.4%) had suffered from MG for less than 10 years. In three out of 10 cases (30.9%), the diagnosis of MG lasted 3 years or longer. The diagnostic delay was significantly longer in female respondents than in the males (p = 0.029). Cholinergic drugs were used in 92.9% of cases initially, and as maintenance therapy in 84.3% of cases. Corticosteroids were used in initiating therapy (45.8%) and as maintenance therapy (46.4%). One in four respondents (25.5%) reported experiencing very strong and strong side effects after using steroids. The side effects from steroid therapy very strong or strong affected overall physical health in 55.9% of respondents, very strong or strong affected self-acceptance in 52%, to a very large or large extent on mental health in 47.1%, and to a very strong or strong extent influenced the performance of daily activities in 28.2%. More than half of the respondents (57.0%) had had a thymectomy. Seven out of 10 respondents (72.0%) declared that the therapy they were on at the time of the survey allowed them (to varying degrees) to control their course of MG. Low therapy acceptance and less well controlled MG was associated with a preference for non-tablet therapies (p = 0.045). Regular follow-up and cooperation with the specialist health care system should improve MG symptoms, activities of daily living, and quality of life.

Epigenome-wide DNA methylation analysis of myasthenia gravis

Myasthenia gravis (MG) is a common neuromuscular junction disorder and autoimmune disease mediated by several antibodies. Several studies have shown that genetic factors play an important role in MG pathogenesis. To gain insight into the epigenetic factors affecting MG, we report here genome-scale DNA methylation profiles of MG. DNA was extracted from eight MG patients and four healthy controls for genome-wide DNA methylation analysis using the Illumina HumanMethylation 850K BeadChip. Verification of pyrosequencing was conducted based on differential methylation positions. Subsequently, C2C12 and HT22 cell lines (derived from mouse) were treated with demethylation drugs. Transcribed mRNA of the screened differential genes was detected using quantitative real-time PCR. The control and MG group were compared, and two key probe positions were selected. The corresponding genes were CAMK1D and CREB5 (P < 0.05). Similarly, the myasthenic crisis (MC) and non-MC group were compared and four key probe positions were selected. The corresponding genes were SAV1, STK3, YAP1, and WWTR1 (P < 0.05). Subsequently, pyrosequencing was performed for verification, revealing that hypomethylation of CAMK1D was significantly different between the MG and control group (P < 0.001). Moreover, transcription of CREB5, PKD, YAP1, and STK3 genes in the C2C12 cells was downregulated (P < 0.05) after drug treatment, but only YAP1 mRNA was downregulated in HT22 cells (P < 0.05). This is the first study to investigate genome-scale DNA methylation profiles of MG using 850 K BeadChip. The identified molecular markers of methylation may aid in the prevention, diagnosis, treatment, and prognosis of MG.

Comparison between mono-tacrolimus and mono-glucocorticoid in the treatment of myasthenia gravis

OBJECTIVE

Use of tacrolimus in mild to moderate myasthenia gravis (MG) is generally limited to glucocorticoid-refractory cases; the advantage of mono-tacrolimus over mono-glucocorticoids is unknown.

METHODS

We included mild to moderate MG patients treated with mono-tacrolimus (mono-TAC) or mono-glucocorticoids (mono-GC). The correlation between the immunotherapy options and the treatment efficacy and side effects were examined in 1:1 propensity-score matching. The main outcome was time to minimal manifestations status or better (MMS or better). Secondary outcomes include time to relapse, the mean changes in Myasthenia Gravis-specific Activities of Daily Living (MG-ADL) scores and the rate of adverse events.

RESULTS

Baseline characteristics showed no difference between matched groups (49 matched pairs). There were no differences in median time to MMS or better between the mono-TAC group and mono-GC group (5.1 vs. 2.8 months: unadjusted hazard ratio [HR], 0.73; 95% CI, 0.46-1.16; p = 0.180), as well as in median time to relapse (data unavailable for the mono-TAC group since 44 of 49 [89.8%] participants remained in MMS or better; 39.7 months in mono-GC group: unadjusted HR, 0.67; 95% CI, 0.23-1.97; p = 0.464). Changes in MG-ADL scores between the two groups were similar (mean differences, 0.3; 95% CI, -0.4 to 1.0; p = 0.462). The rate of adverse events was lower in the mono-TAC group compared to the mono-GC group (24.5% vs. 55.1%, p = 0.002).

INTERPRETATION

Mono-tacrolimus performs superior tolerability with non-inferior efficacy compared to mono-glucocorticoids in mild to moderate myasthenia gravis patients who refuse or have a contraindication to glucocorticoids.

Myasthenia gravis and congenital myasthenic syndromes

Myasthenia gravis is an autoimmune disorder caused by antibodies against elements in the postsynaptic membrane at the neuromuscular junction, which leads to muscle weakness. Congenital myasthenic syndromes are rare and caused by mutations affecting pre- or postsynaptic function at the neuromuscular synapse and resulting in muscle weakness. MG has a prevalence of 150-250 and an annual incidence of 8-10 individuals per million. The majority has disease onset after age 50 years. Juvenile MG with onset in early childhood is more common in East Asia. MG is subgrouped according to type of pathogenic autoantibodies, age of onset, thymus pathology, and generalization of muscle weakness. More than 80% have antibodies against the acetylcholine receptor. The remaining have antibodies against MuSK, LRP4, or postsynaptic membrane antigens not yet identified. A thymoma is present in 10% of MG patients, and more than one-third of thymoma patients develop MG as a paraneoplastic condition. Immunosuppressive drug therapy, thymectomy, and symptomatic drug therapy with acetylcholine esterase inhibitors represent cornerstones in the treatment. The prognosis is good, with the majority of patients having mild or moderate symptoms only. Most congenital myasthenic syndromes are due to dysfunction in the postsynaptic membrane. Symptom debut is in early life. Symptomatic drug treatment has sometimes a positive effect.

Invigorating spleen, replenishing qi and tonifying kidney method treatment of traditional Chinese medicine for myasthenia gravis: A protocol for systematic review and meta-analysis

BACKGROUND

Myasthenia gravis (MG) is an autoimmune disease related to the production of autoantibodies. It is mediated by antibodies against acetylcholine receptor (AChR), muscle specific kinase (MuSK) or other AChR related proteins in the postsynaptic muscle membrane, which interfere with the transmission of signals at the neuromuscular junction, resulting in clinical symptoms of skeletal muscle weakness and fatigue, leading to the occurrence and development of MG. At present, the incidence rate of Mg is increasing year by year. At present, the method of invigorating spleen, replenishing qi and tonifying kidney in traditional Chinese medicine has been widely used in the clinical treatment of MG, and the effect is good. The purpose of this study was to systematically evaluate the efficacy and safety of the method of invigorating the spleen, supplementing qi and tonifying the kidney in the treatment of MG.

METHODS

We will search from the following eight databases: PubMed, Cochrane Library, EMBASE, Web of Science, CNKI, Sinomed, Wanfang, and Vip. All randomized controlled trial (RCT) literature has been searched and classified since the establishment of the database to date. In this study, two researchers independently screened and evaluated the quality of the retrieved literature. Cochrane risk bias assessment tool was used to evaluate the risk of bias. The meta-analysis uses RevMan 5.3 software provided by Cochrane Collaboration Network for meta analysis.

RESULTS

This study compared the main outcome indicators: clinical response rate, recurrence rate, incidence of adverse reactions, quantitative myasthenia gravis score (QMG). Secondary outcomes were clinical absolute score, quality of life score (QOL), levels of inflammatory factors such as IL-6, IL-10, and serum acetylcholine receptor antibody (AChR-Ab) levels.

CONCLUSION

The purpose of this study was to evaluate the efficacy and safety of the method of invigorating the spleen, supplementing qi and tonifying the kidney in treating MG, and to provide evidence based medicine.

Exploring the Potential Mechanism of Qi-Shen-Di-Huang Drug Formulary for Myasthenia Gravis (MG) based on UHPLC-QE-MS Network Pharmacology and Molecular Docking Techniques

Myasthenia gravis (MG) is a rare and refractory autoimmune disease, and Qi Shen Di Huang (QSDH) drug formulary is an in-hospital herbal decoction with proven clinical efficacy in treating MG. Currently, most of the research on the QSDH drug formulary has concentrated on its clinical efficacy, and there is a lack of systematic study on the material basis. The active compounds and their mechanism of action have not been entirely determined. Therefore, this study sought to identify the active compounds in the QSDH drug formulary and analyze the key targets and potential mechanisms. We used ultra-performance liquid chromatography Q Exactive-mass spectrometry (UHPLC-QE-MS) and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database to identify and screen 85 active ingredients corresponding to 59 potential targets (17 herbs) associated with myasthenia gravis, and further identified AKT1 as the primary core target and the PI3K/AKT signaling pathway as the most substantial enriched pathway. Molecular docking and UPLC-MS analysis identified quercetin, luteolin, wogonin, kaempferol, laccasein, and epigallocatechin gallate are the core compounds of the QSDH drug formulary. In vivo rat studies showed that the QSDH drug formulary reduced Lennon's clinical score and decreased acetylcholine receptor antibody levels in peripheral blood rats with experimental autoimmune myasthenia gravis. In addition, the QSDH drug formulary downregulated P-PI3K/PI3K and P-Akt/Akt protein expression. Collectively, these findings describe the role and potential mechanism of the QSDH drug formulary in the treatment of MG, which exerts potential value by acting on AKT targets and regulating the PI3K/AKT signaling pathway and providing a theoretical reference for QSDH drug formulary application in the clinical treatment of MG.

The relationship between anthropometric indicators and health-related quality of life in a community-based adult population: A cross-sectional study in Southern China

Background

This study was designed to analyze the relationship of waist circumference (WC), body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), relative fat mass (RFM), lipid accumulation product (LAP) and health-related quality of life (HRQoL) in the community-dwelling population of southern China and to explore the independent contribution of socio-demographic characteristics, number of chronic diseases and anthropometric indicators to HRQoL in that population.

Methods

This community-based cross-sectional survey studied 2,663 adults aged 18 years and older. HRQoL was assessed by the 3-level EuroQol 5-dimensional scale (EQ-5D-3L), and HRQoL were calculated using the Chinese EQ-5D-3L value set. The outcome variable was the EQ-5D-3L score (HRQoL). Cluster regression was used to analyse the independent contribution of each obesity indicator to HRQoL.

Results

A total of 2,663 people participated in this study, and their mean EQ-5D-3L score was 0.938 ± 0.072. In this study, according to the results of the one-way ANOVA, HRQoL was significantly different between the groups of WHtR, WHR, RFM and LAP, respectively. The independent contributions of socio-demographic factors, number of chronic diseases and anthropometric measures to HRQoL in the whole population accounted for 76.2, 7.9, and 15.9% of the total effect, respectively.

Conclusion

RFM and LAP were found to have a previously unreported negative impact on HRQoL in a community-dwelling population. In future studies, RFM and LAP could be used as new indicators of obesity to predict quality of life in humans.

Clinical characteristics and prognosis of amyotrophic lateral sclerosis with autoimmune diseases

Introduction

The occurrence of autoimmune diseases (AIDs) in amyotrophic lateral sclerosis (ALS) patients is widely reported, but little is known about the associated clinical phenotype. This study aims to evaluate the clinical features and prognosis of ALS patients with AID.

Methods

This retrospective study was based on the ALS Registry dataset of Peking Union Medical College Hospital from 2013 to 2020. Clinical features and inflammatory biomarkers at registration were compared between ALS patients with coexisting AIDs and those without (controls). The medical records of immunotherapy were also collected. The Kaplan–Meier method and Cox proportional hazard model were used to study the survival of ALS patients.

Results

There are 26 (1.6%) ALS patients with AIDs in our database. The ALS patients with AIDs had older ages at onset and poorer respiratory function than controls (p<0.05). After propensity score matching by sex, onset age, and disease duration, the difference in respiratory function remained significant between groups. We found no differences in overall survival between ALS patients with and without AIDs before and after matching (p = 0.836; p = 0.395). Older age at onset, rapid disease progression, and lower erythrocyte sedimentation rate (ESR) were associated with shorter survival (p<0.05). Among ALS patients with AIDs, 8 (30.8%) had a history of immunotherapy and showed slightly prolonged survival compared with those without immunotherapy, but the results did not reach statistical significance (p = 0.355).

Conclusions

Patients with coexisting ALS and AIDs had older onset age and poorer respiratory function but similar overall survival than those with pure ALS.

Myasthenia Gravis: Epidemiology, Pathophysiology and Clinical Manifestations

Myasthenia gravis (MG) is an autoimmune neurological disorder characterized by defective transmission at the neuromuscular junction. The incidence of the disease is 4.1 to 30 cases per million person-years, and the prevalence rate ranges from 150 to 200 cases per million. MG is considered a classic example of antibody-mediated autoimmune disease. Most patients with MG have autoantibodies against the acetylcholine receptors (AChRs). Less commonly identified autoantibodies include those targeted to muscle-specific kinase (MuSK), low-density lipoprotein receptor-related protein 4 (Lrp4), and agrin. These autoantibodies disrupt cholinergic transmission between nerve terminals and muscle fibers by causing downregulation, destruction, functional blocking of AChRs, or disrupting the clustering of AChRs in the postsynaptic membrane. The core clinical manifestation of MG is fatigable muscle weakness, which may affect ocular, bulbar, respiratory and limb muscles. Clinical manifestations vary according to the type of autoantibody, and whether a thymoma is present.

The epidemiology of myasthenia gravis

Neuromuscular junction (NMJ) disorders include several dysfunctions that ultimately lead to muscle weakness. Myasthenia gravis (MG) is the most prevalent NMJ disorder with a highly polymorphic clinical presentation and many different faces. Being an autoimmune disease, MG correlates with the presence of detectable antibodies directed against the acetylcholine receptor, muscle-specific kinase, lipoprotein-related protein 4, agrin, titin, and ryanodine in the postsynaptic membrane at the NMJ. MG has become a prototype serving to understand both autoimmunity and the function of the NMJ better. The aim of this review is to synthesize some of the epidemiological data available. Epidemiological data regarding MG are important for postulating hypotheses regarding its etiology and facilitating the description of MG subtypes. Thus, adequate documentation through broad databases is essential. The incidence and prevalence of MG reported around the globe have been rising steadily and consistently over the past decades. Ethnic aspects, gender-related differences, and environmental risk factors have been described, implying that these might contribute to a specific phenotype, further suggesting that MG may be considered an umbrella term that covers several clinical entities.

Gender differences in quality of life among patients with myasthenia gravis in China

Background

Myasthenia gravis (MG), a chronic neuromuscular disorder, can adversely affect patients’ health-related quality of life (HRQoL), especially in women. The study aimed to evaluate the difference in HRQoL of women and men MG patients and explore the factors that mediate the relationship between gender and HRQoL.

Methods

A cross-sectional study was conducted among 1815 patients with MG in China. The revised 15-item MG quality of life scale (MG-QOL15r) was used to access patients’ HRQoL in overall, physical, social and emotional domains. Socio-demographic information, diagnosis and treatment history, comorbidities, social support, active lifestyle and the MG activities of daily living scale (MG-ADL) were recorded and compared between women and men using the Student’s t-test and Pearson’s Chi-square test. Multivariable regression analyses were conducted to identify independent contributors to HRQoL, especially those affecting different gender.

Results

On average, female patients with MG reported a lower MG-QOL15r score than the males (44.49 ± 29.10 vs 49.32 ± 29.18). The association between gender and patients’ HRQoL interacted with the number of comorbidities across the overall, physical and social domains of patients. As the number of comorbidities increased, the scores of HRQoL decreased and it was faster among females than the males (p < 0.05). Moreover, unemployment, exacerbation of the disease, and active lifestyle contributed to the patients’ HRQoL across all domains. Unemployment (β = − 4.99 [95%CI, − 7.80 to − 2.18], p < 0.001) and exacerbations (β = − 8.49 [95%CI, − 11.43 to − 5.54], p < 0.001) were correlated with poorer HRQoL; while an active lifestyle had a positive impact on HRQoL (β = 0.28 [95%CI, 0.16 to 0.40], p < 0.001).

Conclusions

The results indicate that the HRQoL of women MG patients was lower than that of men. The relationship between gender and HRQoL is modulated by the number of comorbidities. Thus, to improve the HRQoL of women MG patients, symptomatic treatments might not be enough, their comorbid conditions should be considered as well. Additionally, employment status, MG exacerbations, and an active lifestyle have been found as determining factors of the patients’ HRQoL, which suggests future interventions should cope with these factors to improve their quality of life.