Epidemiological and clinical characteristics of myasthenia gravis in Belgrade, Yugoslavia (1983-1992)

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.

The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and perioperative management of myasthenia gravis

BACKGROUND

Myasthenia gravis is a rare autoimmune disease caused by antibodies that probably originate from the thymus glands. This study examined the epidemiology of patients with MG, who underwent thymectomy over the last three decades.

METHODS

The objectives of this observational study were to investigate the clinicopathological features, treatment modalities, and prognostic factors for patients with thymic masses, over three decades at the Royal Hospital, Muscat, Oman.

RESULTS

There were 100 patients who underwent thymectomy with a mean (SD) age of 32.0 (8.6) years, of which 20% were men and 80% were women. Their follow up period, cardiac and neurology clinics, ranged from 1.5 to 12.0 years with a mean (SD) of 6.0 (3.0) years. Small percentage of MG patients had diabetes and hypertension and 10% of patients have positive family history of MG. Symptoms at the onset of the disease were ophthalmoplegia in 75%, limb weakness in 39%, bulbar symptoms in 57% and respiratory symptoms in 39% of patients. The Osserman grading was Grade I - 5%, Grade IIA - 39%, Grade IIB - 34%, and Grade III - 22%. Post thymectomy, 21% of patients had complete clinical remission, 76% of patients had significant clinical improvement and 3% had no apparent improvement in their clinical status. Histologically, hyperplasia was found in 57% and involuted thymus in 18% of patients.

CONCLUSION

Thymectomy can reduce patient's need for medication and reduce the severity of MG regardless of age, sex, severity, or length of sickness, or thymic masses. The early-onset, sever M.G, female, thymic hyperplasia benefit the most. Patients classified as Osserman Class IIA and IIB benefit most from this procedure.

Myasthenia gravis: Historical achievements and the "golden age" of clinical trials

Since the death of Chief Opechankanough >350 years ago, the myasthenia gravis (MG) community has gained extensive knowledge about MG and how to treat it. This review highlights key milestones in the history of treatment and discusses the current "golden age" of clinical trials. Although originally thought by many clinicians to be a disorder of hysteria and fluctuating weakness without observable cause, MG is one the most understood autoimmune neurologic disorders. However, studying it in clinical trials has been challenging due to the fluctuating nature of the medical condition which impacts MG clinical outcomes. Clinical trials must also account for the possibility of a placebo effect. Because MG is a rare incurable autoimmune disorder, it limits the number of potential patients available to participate in clinical trials. In the last 15 years, however, significant progress has been made with MG randomized clinical trials, resulting in a new drug (eculizumab) for physicians' treatment repertoire and an old technique (thymectomy) confirmed effective for MG. Some of the therapies (eg, thymectomy, corticosteroids, plasma exchange, and intravenous immunoglobulin [IVIg]) have survived the test of time. Others (eg, eculizumab and neonatal Fc receptor inhibitor) are novel and hold promise.

Efficacy of prednisone for the treatment of ocular myasthenia (EPITOME): A randomized, controlled trial

INTRODUCTION

In this study we evaluated the safety, tolerability, and efficacy of prednisone in patients with ocular myasthenia gravis (OMG) concurrently treated with pyridostigmine.

METHODS

This investigation was a randomized, double-blind, placebo-controlled trial. Participants whose symptoms failed to remit on pyridostigmine were randomized to receive placebo or prednisone, initiated at 10 mg every other day, and titrated to a maximum of 40 mg/day over 16 weeks. The primary outcome measure was treatment failure.

RESULTS

Fewer subjects were randomized than the 88 planned. Of the 11 randomized, 9 completed 16 weeks of double-blind therapy. Treatment failure incidence was 100% (95% CI 48%-100%) in the placebo group (n = 5) vs. 17% (95% CI 0%-64%) in the prednisone group, P = 0.02 (n = 6). Median time to sustained minimal manifestation status (MMS) was 14 weeks, requiring an average prednisone dose of 15 mg/day. Adverse events were infrequent and generally mild in both groups.

CONCLUSIONS

A strategy of low-dose prednisone with gradual escalation appears to be safe, well-tolerated, and effective in treating OMG.

Incidence of thymoma in myasthenia gravis: a systematic review

Background and Purpose

Myasthenia gravis (MG) is usually comorbid with thymoma. More accurate estimates of the incidence thymoma in MG will help inform patients and their physicians, facilitate health policy discussions, provide etiologic clues, and optimize the management of MG.

Methods

We conducted a systematic review search of relevant English-language studies published between 1960 and 2012 using MEDLINE and Embase. We identified additional studies by reviewing the bibliographies of the retrieved articles and hand searched the main neurology journals. Only incidence studies and case series of unselected MG patients in which information about thymoma were included.

Results

Out of 2206 potentially relevant studies, 49 met the inclusion criteria. Although there was a considerable degree of heterogeneity, the pooled estimate of the incidence of thymoma in MG was 21% (95% confidence interval, 20-22%). The pooled incidence was significantly higher for surgery-based studies than for population- and hospital-based studies. A large proportion of the reported thymomas were noninvasive. Furthermore, thymoma appears to occur significantly more frequently among male MG patients and those older than 40 years at the onset of MG.

Conclusions

Thymoma is common in MG patients, but appears to be found more often in male MG patients and those older than 40 years at the onset of MG. Further research is needed to expand our understanding of these association conditions.

Transmission of maternal muscle-specific tyrosine kinase (MuSK) to offspring: report of two cases

Familial occurrence of myasthenia gravis is uncommon and reports of maternal transmission of muscle-specific tyrosine kinase (MuSK) antibody myasthenia are rarer still. We report two families with maternal transmission of MuSK antibody myasthenia gravis to the offspring by different mechanisms. The first family demonstrates transmission genetic susceptibility of inheriting myasthenia gravis from MuSK antibodies, whereas the second one demonstrates transplacental transmission of MuSK antibodies at birth.

Frequency of autoimmune diseases in myasthenia gravis: a systematic review

The course of myasthenia gravis (MG) may get complicated by the development of other autoimmune diseases. Estimates of the frequency of autoimmune diseases will help inform patients and physicians, direct health policy discussion, provide etiologic clues, and optimize the management of MG. However, the frequency of autoimmune diseases in people with MG is still uncertain. A systematic search for English language studies was conducted by MEDLINE and EMBASE from 1960 through 2010. Incidence studies and case series of all MG subtypes with information about autoimmune diseases were included; 25 studies met the inclusion criteria. Although there was considerable heterogeneity, the pooled estimate of the coexisting autoimmune diseases in MG was 13% (95% confidence interval, 12%-14%). Autoimmune thyroid disease seems to occur more frequently than other autoimmune conditions in MG patients. Heterogeneity in study estimates could be explained by ascertainment bias and case mix. Furthermore, autoimmune diseases occurred significantly more often in females and anti-acetylcholine receptor seropositive MG patients. Patients with MG have an increased frequency of coexisting autoimmune diseases. Autoimmune diseases seem to occur more often in female and seropositive MG patients. Further research is needed to expand our understanding of these associations.

Myasthenia gravis in Ceará, Brazil: clinical and epidemiological aspects

A retrospective chart review was performed on patients diagnosed as having myasthenia gravis in Ceará State, Brazil and who were followed from October 1981 to June 2009. Clinical and epidemiologic aspects were evaluated. In this work, 122 patients were studied, of whom 85 (69.7%) were females and 37 (30.3%) were males. The disease duration ranged from five months to 50 years (8.9±8.1 years). Age at the first symptoms varied from 0 to 74 years (31.9±14.4 years). The first main symptoms and signs were ptosis, diplopia and limb weakness. Generalized myasthenia was the most common clinical presentation, but 5.1% (n=6) persisted as ocular myasthenia. Thymectomy was performed in 42.6% (n=52) of myasthenic patients. A thymoma was present in 10 patients. Serum acetylcholine receptor (AChR) antibodies were present in 80% (n=20) of specimens tested. The data presented are similar to those of studies performed in other countries.

Validation of Serbian version of the disease-specific myasthenia gravis questionnaire

AIM

The aim of this study was to validate translated and cross-cultural adapted Italian version of myasthenia gravis-specific questionnaire (MGQ) in Serbian MG patients.

MATERIALS AND METHODS

The questionnaire was validated in 140 consecutive MG patients from Belgrade. In each patient association between the total MGQ score and form and severity of the disease was determined. Also, correlation between regional domain scores of MGQ and main clinical findings according to Besinger's clinical score was analyzed.

RESULTS

Patients' participation in the assessment was satisfactory with excellent internal consistency and reproducibility. Total MGQ score, as well as domain scores, correlated with highly significant inverse relationship with the disease severity and clinical status of patients at the moment of completing the questionnaire. Furthermore, the bulbar domain of the questionnaire appeared more specific and sensitive than clinical history and examination.

CONCLUSION

We concluded that the Serbian version of the MGQ may be useful as a measure of clinical outcome in patients with MG.

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.

Nationwide population-based epidemiological study of myasthenia gravis in taiwan

BACKGROUND

The purpose of this study is to investigate the epidemiology and medical expenses of myasthenia gravis (MG) in Taiwan.

METHODS

Cases of MG were identified from the National Health Insurance Research Database with corresponding codes of the International Classification of Diseases, ninth revision (ICD-9), from January 2000 to December 2007. Age- and sex-specific incidences were estimated by dividing the incidence number by population data obtained from the Department of Statistics, Ministry of the Interior.

RESULTS

During the study period, 5,211 cases were identified. The incidence ratio of males to females was 0.68. The average annual incidence rate was 2.1/100,000. MG occurred in all age groups with a higher incidence in older individuals and the lowest incidence in the 10- to 14-year-olds for both sexes. Among the 5,211 cases, 615 (12%) had a neoplasm of the thymus. The prevalence increased steadily during the study period from 8.4/100,000 in 2000 to 14.0/ 100,000 in 2007.

CONCLUSIONS

This is the first population-based epidemiological study of MG in Taiwan. The incidence rate and prevalence were higher than in most published studies, especially in old age groups.

Serological and clinical features of patients with myasthenia gravis in north Indian population

Myasthenia gravis (MG) is a disorder of neuromuscular junction associated with presence of antibodies against nicotinic acetylcholine receptors (nAChRs). Here, we compared the clinical and serological profile of seropositive myasthenia gravis (SPMG) and seronegative myasthenia gravis (SNMG) patients. Anti-AChR antibody was measured using radio receptor immunoassay and correlated with clinical phenotype in 250 MG patients over 2004 and 2006. Out of 250 MG patients, 161 (64.4%) were males (male:female = 1.8:1). SNMG patients formed 40% (n = 101) of our MG patients which is much higher as compared to Caucasian and Oriental population (15%-20%). The median age of disease onset in SPMG was significantly higher than SNMG patients (43 years; range 8-74 vs. 35 years; range 4-72, p = .022). A bimodal peak of age of disease onset in both genders was observed (first peak in second-third decades and second one in fifth-sixth decades). Among the MG patients with late-onset of disease, male were significantly higher compared to Caucasian and Oriental MG population (p = .047). MG patients with thymoma were significantly older and consisted of higher percent of males. Bulbar symptoms and severe grade (IIB+ III+ IV) at disease onset were more frequent in SPMG than SNMG patients.

Epidemiological study of muscular disorders in Assiut, Egypt

Few comprehensive epidemiological studies of the prevalence of muscle diseases have been undertaken, and none has been carried out in our locality. The present cross-sectional study was conducted in Assiut Governorate (Upper Egypt) to estimate the prevalence of different types of primary muscular disorder in 1997. The study involved 52,203 subjects, 15,617 (30%) from the rural community and 36,586 (70%) from the urban community. Patients were identified from a door-to-door survey, and all were subjected to a full clinical examination, with confirmation of the diagnosis through electrophysiological, and biochemical investigations. Histopathological studies were performed for the classification of muscular dystrophies. Forty patients with muscular disorders were identified, with a point prevalence of 76.6 per 100,000 in the total community with no significant differences between the rural and urban communities. The creatine kinase level was abnormally high (>225 IU/l) in 80% of the cases, increased in all patients with muscular dystrophy or myositis, in 88.8% of patients with systemic myopathy and 66.6% of patients with myotonia. None of the cases of myasthenia showed an increase in the creatine kinase level. The lifetime prevalence per 100,000 was 26.8 for muscular dystrophy, 11.49 for myotonia, 11.49 for myositis, 17.24 for systemic myopathy and 9.57 for myasthenia.

Dental management of patients with myasthenia gravis: A literature review

Myasthenia gravis is a chronic neuromuscular disease characterized by muscular weakness and fatigability. Dental management of patients diagnosed with myasthenia gravis presents a challenge to the dental profession. A MEDLINE search of the English medical (limited to provision in dental care) and dental literature on myasthenia gravis and dental management published between 1975 and 2004 was conducted. In the dental literature, 12 articles were found, and only a few focused on myasthenia gravis and dental care. The purpose of this article was to review and summarize the clinical signs and symptoms associated with myasthenia gravis, highlighting the role of the dental profession in the process of the diagnosis and management of the oral and dental complications that might be associated with the disease, while avoiding myasthenic crisis.

Non-thyroid autoantibodies in autoimmune thyroid disease

Autoimmune thyroid disease is frequently accompanied by other organ-specific and non-organ-specific diseases, most likely because there is sharing of genetic and possibly environmental susceptibility factors. These associations are well recognized in the autoimmune polyglandular syndromes; autoimmune thyroid disease is one of the three major endocrinopathies in the type 2 syndrome and occurs in around 4% of type 1 patients. This review considers the frequency of disease-specific autoantibodies in patients with thyroid autoimmunity and briefly examines the role of such antibodies in performing screening for the associated conditions. Recommendations are made for using such autoantibody tests in the setting of patients with autoimmune thyroid disorders, and also for the utility of screening for thyroid autoimmunity in patients with pernicious anaemia, Addison's disease, coeliac disease, primary biliary cirrhosis, myasthenia gravis, lymphocytic hypophysitis, systemic lupus erythematosus and rheumatoid arthritis. At present, however, there are no large-scale trials that have shown the cost-benefit ratio of autoantibody screening for autoimmunity screening, and clinicians must use individual judgement combined with heightened awareness to identify who to test.

The epidemiology of myasthenia gravis

Population-based studies of the epidemiology of myasthenia gravis (MG) have been conducted for over 50 years. Over that time, there has been a clear trend towards an increase in the reported prevalence of the disease. In recent years, there has also been an interest in determining a reasonably accurate estimate of the number of MG patients in the United States. Current estimates place the prevalence at a high value of about 20 per 100,000. The year 2000 U.S. population estimate is slightly less than 280 million. A crude estimate of the number of MG patients derived from the population estimate and the reported prevalence from selected populations indicates that there are between 53,000 and 59,900 patients in the United States at this time. The age and ethnic distributions in the United States are evolving from those that were present when the majority of the population-based studies were done, and the distribution of severity of the disease may also have changed. Future studies of the epidemiology of MG should take these factors into account, and further research into the economic and quality-of-life impact of the disease in the population is needed.

A population based epidemiological study on myasthenia gravis in Estonia

OBJECTIVE

To describe the occurrence of myasthenia gravis in the Baltic area.

METHODS

Data were obtained from hospital files recorded during the period 1942 to 1996 from neurologists and the patient organisation. Survival data were checked with the Estonian Citizenship and Migration Board. Prevalence was determined on 1 January 1997. A questionnaire on the course of myasthenia gravis was sent to all the prevalent patients.

RESULTS

The size of the population surveyed was 1 462 130. The average annual incidence from 1970 to 1996 was 4.0 per million (women, 5.2; men, 2.6). The point prevalence was 99 per million (women, 133; men 59). The incidence in the younger age group (<50 years) was 3.4 per million (women, 4.8; men, 1.9) and in the older age group (>or=50 years), 5.5 (women, 5.9; men, 4.9). The prevalence ratio was twofold higher in the older age group (p<0.0001)-for men (p = 0.034) as well as for women (p<0.001).

CONCLUSIONS

Prevalence and incidence values of myasthenia gravis from Estonia are similar to those reported in most studies from Europe and north America. However, there seems to be a higher frequency in the elderly (>or=50 years) in Estonia.

A limited epidemiological study of seropositive myasthenia gravis in Tayside

Myasthenia gravis is an acquired disorder of the neuromuscular junction characterised by fatiguable weakness of the limbs, bulbar and facial muscles and may be complicated by respiratory muscle weakness and failure. One often confirms the diagnosis by a simple serological test looking for the presence of the nicotinic acetylcholine receptor antibody. However, seronegative myasthenia constitutes about 20% of cases and in the case of ocular myasthenia, only 50% will have the antibody. Therefore, the diagnosis can be less than straightforward especially if the patient presents with vague symptoms such as fatigue or presents to specialities other than neurology or ophthalmology. The fact that the diagnosis may prove to be challenging, compounded by the fact that the condition is relatively rare and that the antibody to the acetylcholine receptor is not always present, epidemiological data is often less than precise and indeed difficult to acquire. We felt it was necessary to try to establish the epidemiological data on seropositive myasthenia gravis in Tayside, (this has never been carried out) bearing in mind the above pitfalls, and see how the incidence compares with similar and previous studies.

Long-term follow-up of myasthenia gravis patients with hyperthyroidism

OBJECTIVE

To access clinical characteristics and treatment outcome of myasthenia gravis (MG) patients with hyperthyroidism (HT).

MATERIALS AND METHODS

The clinical characteristics of 51 MG patients with HT were studied. The treatment outcome was analysed in 34 patients, comparing high-dosage prednisolone (HDP) (group IS), HDP and/or immunosuppressants with antithyroid drugs (group IS + antiHThyr), antithyroid drugs (group antiHThyr), and thymectomy.

RESULTS

The prevalence of HT in MG was 17.5%. Group IS showed higher remission of both diseases compared with group antiHThyr, but not with group IS + antiHThyr. Remission of HT and relapse of both diseases showed no difference among the three groups. Ten patients who had thymectomies had a lower relapse of MG but not of HT, whilst remission of both diseases was no different to 24 non-thymectomy patients.

CONCLUSION

This study showed a high prevalence of HT in Thai MG. HDP alone can induce remission of both diseases without difference in relapse. Thymectomy lowers MG relapse further but has no influence on HT.

Gender prevalence in childhood multiple sclerosis and myasthenia gravis

Multiple sclerosis and myasthenia gravis are the most common autoimmune diseases affecting the nervous system, with generally a female predominance in adults. To determine the gender distribution in childhood, we reviewed 28 patients with definite multiple sclerosis and 44 patients with myasthenia gravis with onset before 16 years. In myasthenia gravis, a significant female preponderance was observed only with onset after 10 years of age; earlier disease showed no gender difference. Multiple sclerosis tended to affect boys more than girls before age 10 years and both sexes equally after this age. Gender prevalence in childhood multiple sclerosis and myasthenia gravis is different than in adult series; these results may provide insight into pathogenesis or clinical approach.

Epidemiology of seropositive myasthenia gravis in Greece

OBJECTIVES

To study the epidemiological characteristics of myasthenia gravis in Greece.

METHODS

A population based study was carried out of seropositive myasthenia gravis in Greece for the period from 1 January 1983 to 30 June 1997; 843 patients were studied.

RESULTS

The average annual incidence for the period 1992-7, for which the database is complete, was 7.40/million population/year (women 7.14; men 7.66). On 1 July 1997, there were 740 prevalent cases. The point prevalence rate was 70.63/million (women 81.58; men 59.39). The average overall annual mortality rate in the patients was 0.67/million population (women 0.53; men 0.82), and the mortality rate attributed to myasthenia gravis was 0.43/million population (women 0.41; men 0.45). The average age at onset was 46.50 years (women 40.16; men 54.46), and the mean age of the prevalent patients was 52.58 (women 47.65; men 59.48). The women:men incidence ratio was 1:1.04, and the prevalence ratio was 1.41:1. It is predicted that the prevalence and women: men prevalence ratio would increase if the patient list included all patients with a date of onset before 1983.

CONCLUSIONS

The largest epidemiological study ever performed on myasthenia gravis is presented. The most important epidemiological indexes are provided.