Rationale for the clinical guidelines for myasthenia gravis in Japan

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.

Impact of Early Treatment with Intravenous High-Dose Methylprednisolone for Ocular Myasthenia Gravis

The efficacy of intravenous high-dose methylprednisolone (IVMP) in ocular myasthenia gravis (MG) has not been fully established. This study aimed to elucidate the effects of early intervention with IVMP for achieving the therapeutic targets (minimal manifestations [MM] or MM or better status with prednisolone ≤ 5 mg/day [MM5mg]) in ocular MG. In this observational study, we included a total of 1710 consecutive patients with MG enrolled in the Japan MG Registry in 2021. Of these, 204 patients with ocular MG who received immunotherapy were analyzed. The clinical course and time to first achieve MM or MM5mg after starting immunotherapy were compared between the early IVMP group (treated with IVMP within 3 months of treatment initiation) and the non-early IVMP group. Despite having greater clinical severity before immunotherapy and lower oral prednisolone doses throughout the course, the early IVMP group (n = 55) showed a higher rate of achievement of MM (P = 0.0040, log-rank test; hazard ratio 1.58, 95% confidence interval [CI] 1.13-2.20, P < 0.0001) and MM5mg (P = 0.0005, log-rank test; hazard ratio 1.78, 95% CI 1.27-2.51, P < 0.0001) compared with the non-early IVMP group (n = 149). In conclusion, an early intervention with IVMP is likely to increase the probability of achieving a better long-term outcome and reducing the total dose of corticosteroids in ocular MG.

Iron metabolism in non-anemic myasthenia gravis patients: A cohort study

BACKGROUND

The association of iron metabolism parameters with disease severity and outcome in myasthenia gravis (MG) patients has not been reported. This study was conducted to determined clinical factors including iron metabolism parameters correlated with disease severity and future outcome in non-anemic immunotherapy-naïve MG patients first receiving immunotherapy.

MATERIAL AND METHODS

One hundred and ten patients were included at baseline to explore predictor variables associated with disease severity represented by variables derived from MG activities of daily living (MG-ADL) score using multivariate logistic regression, after which 103 and 98 patients were included respectively in multivariate survival analyses at 6-month and 12-month follow-up to identify predictors for minimal manifestation status (MMS) after starting immunotherapy.

RESULTS

Higher ferritin level was independently associated with higher risk of severe generalized disease in non-anemic immunotherapy-naïve MG patients. Total iron binding capacity <250 μg/dL and the interval between onset and immunotherapy <1 year were independent predictors for MMS at 6-month and 12-month follow-up after initiating immunotherapy. Transferrin <2.00 g/L was an independent predictor for MMS at 12-month follow-up.

CONCLUSION

Iron metabolism parameters might be promising biomarkers for evaluating disease severity and guiding therapeutic decision in MG patients.

Efgartigimod for generalized myasthenia gravis with or without anti-acetylcholine receptor antibodies: a worldwide and Japanese perspective

INTRODUCTION

The management of myasthenia gravis (MG) has been improved due to immunotherapy advances, but 20% of individuals with MG are refractory to the conventional therapy, and the need for novel biological drugs remains.

AREA COVERED

The Japanese clinical guidelines for MG published in May 2022 include the concept that treatment is often lifelong and should aim to maintain a sufficient quality of life and mental health. We provide an overview of the therapeutic strategy for generalized MG in Japan, in comparison with the international consensus. We summarize the clinical efficacy, safety, and tolerability of efgartigimod, the first approved anti-neonatal Fc receptor inhibitor for MG. A phase III study showed that efgartigimod was well-tolerated and efficacious in patients with generalized MG.

EXPERT OPINION

Efgartigimod is a promising biological drug for patients with moderate to severe generalized MG with or without anti-acetylcholine receptor antibodies in Japan.

Factors affecting minimal manifestation status induction in myasthenia gravis

Background:

Minimal manifestation status (MMS) is an important landmark in the treatment of myasthenia gravis (MG), and predictors of MMS induction have rarely been identified in previous studies.

Objective:

The objective of this study is to evaluate the clinical factors associated with MMS induction among patients with MG.

Design:

This two-step retrospective cohort study with a single center investigated the factors that may be associated with MMS induction and retested these predictors in a test cohort.

Methods:

A total of 388 diagnosed MG patients who visited Xiangya Hospital between 1 July 2015 and 1 July 2019 were involved. We performed detailed chart reviews and recorded all cases achieving MMS. Demographics and clinical characteristics were also collected and their relationships to achieving MMS were investigated.

Results:

MMS was achieved in 124 patients (50.2%), and the median time to achieve MMS was 26 months. Several factors were found to be associated with MMS induction in exploring cohort, including muscle-specific tyrosine-protein kinase receptor (MuSK) antibody positivity (adjusted hazard ratio, HR = 4.333, 95% confidence interval, CI: 1.862–10.082), isolated ocular involvement (adjusted HR = 1.95, 95% CI: 1.284–2.961), and low baseline quantitative myasthenia gravis score (QMG score; adjusted HR = 2.022, 95% CI: 1.086–3.764). These factors were then retested in the test cohort. Isolated ocular involvement or low baseline QMG scores were factors found to be beneficial for MMS induction were confirmed.

Conclusion:

Isolated ocular involvement and low baseline QMG score are predictors of MMS induction in MG patients.

A Comparison of Clinical, Electro-Diagnostic, Laboratory, and Treatment Outcome Differences in a Cohort of HIV-Infected and HIV-Uninfected Patients With Myasthenia Gravis

There is limited literature comparing the clinical parameters and treatment outcomes in HIV-infected and HIV-uninfected myasthenia gravis (MG) patients. The aim of the study was to investigate the clinical differences and treatment outcomes in the two categories of patients, particularly the safe use of immunosuppressive therapy in immunocompromised patients. The study was a retrospective analysis of medical records of MG patients from the neuromuscular unit at Inkosi Albert Luthuli Central Hospital in Kwa-Zulu Natal between 2003 and 2019. One hundred and seventy-eight (178) patients fulfilled the clinical criteria for MG. Twenty-four (13.4%) were HIV-infected and 154 (86.5%) were HIV-uninfected. There were 116 (65%) females, median 45 years, (IQR 40–62), 90 (50.5%) black African, 66 (37%) Indian, 20 (11.2%) white, and 2 (1.1%) of mixed ancestry. In the HIV-infected cohort, 20 (87%) had generalized MG, 12 (50%) bulbar, and 14 (60.9%) respiratory onset MG, 12 (50%) presented with MG Foundation of America (MGFA) class five diseases at diagnosis, six (25%) presented with MG crisis during the 5-year follow-up. Thirteen (54%) of the HIV-infected group required rescue therapy using (plasma exchange or IV immunoglobulin) combined with pulse cyclophosphamide compared with 17 (11%) in the HIV-uninfected cohort, respectively. At 5 years, 8 (33%) of the HIV-infected group remained refractory to treatment compared with 10 (6.5%) HIV-uninfected cohort, respectively. No adverse events were documented in HIV-infected patients receiving combination rescue therapy (PLEX or IVIG combined with IV cyclophosphamide). In conclusion HIV-infected MG patients are more likely to require combination rescue therapy with PE/IVIG and IV cyclophosphamide compared with those who were HIV-uninfected. No side effects were documented in the HIV-infected group receiving the above therapy.

Clinical Predictors of Prolonged Hospital Stay in Patients with Myasthenia Gravis: A Study Using Machine Learning Algorithms

Myasthenia gravis (MG) is an autoimmune disorder that causes muscle weakness. Although the management is well established, some patients are refractory and require prolonged hospitalization. Our study is aimed to identify the important factors that predict the duration of hospitalization in patients with MG by using machine learning methods. A total of 21 factors were chosen for machine learning analyses. We retrospectively reviewed the data of patients with MG who were admitted to hospital. Five machine learning methods, including stochastic gradient boosting (SGB), least absolute shrinkage and selection operator (Lasso), ridge regression (Ridge), eXtreme gradient boosting (XGboost), and gradient boosting with categorical features support (Catboost), were used to construct models for identify the important factors affecting the duration of hospital stay. A total of 232 data points of 204 hospitalized MG patients admitted were enrolled into the study. The MGFA classification, treatment of high-dose intravenous corticosteroid, age at admission, treatment with intravenous immunoglobulins, and thymoma were the top five significant variables affecting prolonged hospitalization. Our findings from machine learning will provide physicians with information to evaluate the potential risk of MG patients having prolonged hospital stay. The use of high-dose corticosteroids is associated with prolonged hospital stay and to be used cautiously in MG patients.

Rate of change in acetylcholine receptor antibody levels predicts myasthenia gravis outcome

OBJECTIVE

To investigate the association between changes in anti-acetylcholine receptor antibody (AChR Ab) levels induced by immunosuppressive treatment and myasthenia gravis (MG) prognosis at 1-year post-treatment in patients with MG.

METHODS

We included 53 consecutive AChR Ab-positive patients with MG whose AChR Ab levels were remeasured within 100 days of initiating immunosuppressive treatment (median remeasuring time post-treatment: 71 (55-84) days). The AChR Ab level reduction rate (RR-AChRAb, %/day) adjusted for the time between treatment initiation, and AChR Ab level remeasurement was calculated as follows: (pretreatment-post-treatment AChR Ab level)/pretreatment AChR Ab level/days between therapy initiation and AChR Ab level remeasurement ×100. Participants were divided into two groups based on the cut-off value of RR-AChR Ab, determined using receiver operating characteristic analyses for achieving minimal manifestation (MM) or better status at 1-year postimmunosuppressive treatment. The Myasthenia Gravis Foundation of America postintervention status and MG activity of daily living (MG-ADL) score at 1-year post-treatment were compared between the two groups.

RESULTS

The RR-AChRAb cut-off value was 0.64%/day. The high RR-AChRAb group had a higher ratio of MM or better status (90% vs 65%, p=0.03) and lower MG-ADL score (median; 1 vs 2, p=0.04) than the low RR-AChRAb group. Kaplan-Meier analyses showed the early MM achievement in the high RR-AChRAb group (p=0.002, log-rank test).

CONCLUSIONS

High RR-AChRAb is associated with a favourable outcome at 1-year post-treatment. AChR Ab remeasurement within 100 days of therapy may be useful for predicting AChR Ab-positive MG outcomes at 1-year post-treatment.

Thymectomy in ocular myasthenia gravis before generalization results in a higher remission rate

OBJECTIVES

This study aimed to compare the outcomes of patients with ocular myasthenia gravis (OMG) who underwent thymectomy before generalization with the outcomes of those who underwent thymectomy after generalization.

METHODS

We retrospectively reviewed patients who underwent robotic thymectomy for myasthenia gravis between January 2003 and February 2018. Patients who presented with purely ocular symptoms at myasthenia gravis onset were eligible for inclusion. Exclusion criteria were patients who were lost to follow-up and patients who underwent re-thymectomy. Patients with OMG who developed generalization before thymectomy were categorized into gOMG group and those who did not were categorized into OMG group. The primary outcome was complete stable remission according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS).

RESULTS

One hundred and sixty-five (66 males and 99 females) out of 596 patients with myasthenia gravis were eligible for inclusion. Of these, there were 73 and 92 patients undergoing thymectomy before and after the generalization of OMG, respectively. After propensity score matching, a data set of 130 patients (65 per group) was formed and evaluating results showed no statistical differences between the 2 groups. The estimated cumulative probabilities of complete stable remission at 5 years were 49.5% [95% confidence interval (CI) 0.345-0.611] in the OMG group and 33.4% (95% CI 0.176-0.462) in the gOMG group (P = 0.0053). Similar results were also found in patients with non-thymomatous subgroup [55 patients per group, OMG vs gOMG, 53.5% (95% CI 0.370-0.656) vs 28.9% (95% CI 0.131-0.419), P = 0.0041].

CONCLUSIONS

Thymectomy in OMG before generalization might result in a higher rate of complete stable remission than thymectomy after generalization.

Long-term outcomes and prognostic factors in generalized myasthenia gravis

OBJECTIVE

This study aimed to investigate the timing of meeting the criteria for a status of "minimal manifestation (MM) or better" and the factors that influenced whether "MM or better status" or "MM or better status with an oral prednisolone (PSL) dose of 5 mg/day or less (5-mg MM)" was met in patients with acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (MG).

METHODS

We performed a retrospective study in 93 patients with AChR antibody-positive generalized MG who were followed for 3 years after the start of immunotherapy. We reviewed clinical data, such as MG-related symptoms, the MG activities of daily living profile (MGADL) score, immunotherapy including the dose of PSL, and achievement of the status of MM or better at baseline and 3, 6, 12, 24, and 36 months after treatment.

RESULTS

An MM or better status was achieved in 60% of the patients 3 months and in 90% of the patients 2 years after initiating immunotherapy. At 2 years, 60% of the patients had achieved the treatment goal, which was an "5-mg MM". More frequent plasmapheresis and higher dose of PSL within 3 months after immunotherapy initiation were associated with difficulty in achieving the 5-mg MM status at 2 years.

CONCLUSION

Approximately 60% of the MG patients achieved the treatment goal within 2 years after treatment. PSL dose and the cumulative number of plasmapheresis procedures at 3 months after immunotherapy initiation may help identify treatment-resistant patients with MG.

Favorable Effects of Tacrolimus Monotherapy on Myasthenia Gravis Patients

Background and Purpose: Tacrolimus (TAC) has been proven to be a rapid-acting, steroid-sparing agent for myasthenia gravis (MG) therapy. However, evidence related to the effectiveness of TAC alone is rare. Therefore, this study was performed to investigate the effect of TAC monotherapy in MG patients.

Methods: Forty-four MG patients who received TAC monotherapy were retrospectively analyzed. A mixed effect model was used to analyze improvements in MG-specific activities of daily living scale (MG-ADL), quantitative MG score (QMG) and MG-ADL subscores. Kaplan-Meier analysis was used to estimate the cumulative probability of minimal manifestations (MM) or better. Adverse events (AEs) were recorded for safety analyses.

Results: Of the patients receiving TAC monotherapy, MG-ADL scores were remarkably improved at 3, 6 and 12 months compared with scores at baseline (mean difference and 95% CIs: −3.29 [−4.94, −1.64], −3.97 [−5.67, −2.27], and −4.67 [−6.48, −2.85], respectively). QMG scores significantly decreased at 6 and 12 months, with mean differences and 95% CIs of −4.67(−6.88, −2.45) and −5.77 (−7.55, −4.00), respectively. Estimated median period to achieve “MM or better” was 5.0 (95% CIs, 2.8, 7.2) months. Ocular MG (OMG) and generalized MG (GMG) showed similar therapeutic effects in cumulative probabilities of “MM or better” (P-value = 0.764). A better response was observed in MG-ADL subscores for ptosis and bulbar symptoms. AEs occurred in 37.5% of patients and were generally mild and reversible.

Conclusions: TAC monotherapy is a promising option to rapidly alleviate all symptoms of MG, especially for ptosis and bulbar symptoms.

A Practical Approach to Managing Patients With Myasthenia Gravis-Opinions and a Review of the Literature

When the diagnosis of myasthenia gravis (MG) has been secured, the aim of management should be prompt symptom control and the induction of remission or minimal manifestations. Symptom control, with acetylcholinesterase inhibitors such as pyridostigmine, is commonly employed. This may be sufficient in mild disease. There is no single universally accepted treatment regimen. Corticosteroids are the mainstay of immunosuppressive treatment in patients with more than mild MG to induce remission. Immunosuppressive therapies, such as azathioprine are prescribed in addition to but sometimes instead of corticosteroids when background comorbidities preclude or restrict the use of steroids. Rituximab has a role in refractory MG, while plasmapheresis and immunoglobulin therapy are commonly prescribed to treat MG crisis and in some cases of refractory MG. Data from the MGTX trial showed clear evidence that thymectomy is beneficial in patients with acetylcholine receptor (AChR) antibody positive generalized MG, up to the age of 65 years. Minimally invasive thymectomy surgery including robotic-assisted thymectomy surgery has further revolutionized thymectomy and the management of MG. Ocular MG is not life-threatening but can be significantly disabling when diplopia is persistent. There is evidence to support early treatment with corticosteroids when ocular motility is abnormal and fails to respond to symptomatic treatment. Treatment needs to be individualized in the older age-group depending on specific comorbidities. In the younger age-groups, particularly in women, consideration must be given to the potential teratogenicity of certain therapies. Novel therapies are being developed and trialed, including ones that inhibit complement-induced immunological pathways or interfere with antibody-recycling pathways. Fatigue is common in MG and should be duly identified from fatigable weakness and managed with a combination of physical therapy with or without psychological support. MG patients may also develop dysfunctional breathing and the necessary respiratory physiotherapy techniques need to be implemented to alleviate the patient's symptoms of dyspnoea. In this review, we discuss various facets of myasthenia management in adults with ocular and generalized disease, including some practical approaches and our personal opinions based on our experience.

Minimal manifestation status and prednisone withdrawal in the MGTX trial

OBJECTIVE

To examine whether sustained minimal manifestation status (MMS) with complete withdrawal of prednisone is better achieved in thymectomized patients with myasthenia gravis (MG).

METHODS

This study is a post hoc analysis of data from a randomized trial of thymectomy in MG (Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy [MGTX]). MGTX was a multicenter, randomized, rater-blinded 3-year trial that was followed by a voluntary 2-year extension for patients with acetylcholine receptor (AChR) antibody-positive MG without thymoma. Patients were randomized 1:1 to thymectomy plus prednisone vs prednisone alone. Participants were age 18-65 years at enrollment with disease duration less than 5 years. All patients received oral prednisone titrated up to 100 mg on alternate days until they achieved MMS, which prompted a standardized prednisone taper as long as MMS was maintained. The achievement rate of sustained MMS (no symptoms of MG for 6 months) with complete withdrawal of prednisone was compared between the thymectomy plus prednisone and prednisone alone groups.

RESULTS

Patients with MG in the thymectomy plus prednisone group achieved sustained MMS with complete withdrawal of prednisone more frequently (64% vs 38%) and quickly compared to the prednisone alone group (median time 30 months vs no median time achieved, p < 0.001) over the 5-year study period. Prednisone-associated adverse symptoms were more frequent in the prednisone alone group and distress level increased with higher doses of prednisone.

CONCLUSIONS

Thymectomy benefits patients with MG by increasing the likelihood of achieving sustained MMS with complete withdrawal of prednisone.

CLINICALTRIALSGOV IDENTIFIER

NCT00294658.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with generalized MG with AChR antibody, those receiving thymectomy plus prednisone are more likely to attain sustained MMS and complete prednisone withdrawal than those on prednisone alone.

Complement Inhibitor Therapy for Myasthenia Gravis

Complement activation as a driver of pathology in myasthenia gravis (MG) has been appreciated for decades. The terminal complement component [membrane attack complex (MAC)] is found at the neuromuscular junctions of patients with MG. Animals with experimental autoimmune MG are dependent predominantly on an active complement system to develop weakness. Mice deficient in intrinsic complement regulatory proteins demonstrate a significant increase in the destruction of the neuromuscular junction. As subtypes of MG have been better defined, it has been appreciated that acetylcholine receptor antibody-positive disease is driven by complement activation. Preclinical assessments have confirmed that complement inhibition would be a viable therapeutic approach. Eculizumab, an antibody directed toward the C5 component of complement, was demonstrated to be effective in a Phase 3 trial with subsequent approval by the Federal Drug Administration of the United States and other worldwide regulatory agencies for its use in acetylcholine receptor antibody-positive MG. Second- and third-generation complement inhibitors are in development and approaching pivotal efficacy evaluations. This review will summarize the history and present the state of knowledge of this new therapeutic modality.

Takotsubo syndrome in patients with myasthenia gravis: a systematic review of previously reported cases

Background

Myasthenia gravis associated takotsubo syndrome is a rare condition. This study aimed to explore its typical presentation, investigations and treatment through a systematic review of previously reported cases.

Methods

Databases and reference lists of the selected articles were searched for case reports on Myasthenia gravis associated takotsubo syndrome. CARE guidelines were used for the quality assessment of the selected articles.

Results

Sixteen cases were selected out of 580 search results. Western Pacific, American and European regions contributed to 88% of the cases. Females were most affected (81%). Features of both myasthenia gravis and takotsubo syndrome were the common clinical presentations. All cases had a myasthenic crisis. Half of the cases had no prior diagnosis of myasthenia gravis. Pyridostigmine and prednisolone were useful for myasthenia gravis while dobutamine was most commonly used for takotsubo syndrome. All cases survived except four (25%).

Conclusions

Myasthenia gravis associated takotsubo syndrome via a myasthenic crisis is rare but life-threatening. Therefore, predisposition due to emotional and physical triggers needs to be avoided for its prevention. The rare entity should be suspected even in patients without a prior diagnosis of Myasthenia gravis.

Long-term efficacy and safety of eculizumab in Japanese patients with generalized myasthenia gravis: A subgroup analysis of the REGAIN open-label extension study

The terminal complement inhibitor eculizumab was shown to improve myasthenia gravis-related symptoms in the 26-week, phase 3, randomized, double-blind, placebo-controlled REGAIN study (NCT01997229). In this 52-week sub-analysis of the open-label extension of REGAIN (NCT02301624), eculizumab's efficacy and safety were assessed in 11 Japanese and 88 Caucasian patients with anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis. For patients who had received placebo during REGAIN, treatment with open-label eculizumab resulted in generally similar outcomes in the Japanese and Caucasian populations. Rapid improvements were maintained for 52 weeks, assessed by change in score from open-label extension baseline to week 52 (mean [standard error]) using the following scales (in Japanese and Caucasian patients, respectively): Myasthenia Gravis Activities of Daily Living (-2.4 [1.34] and - 3.3 [0.65]); Quantitative Myasthenia Gravis (-2.9 [1.98] and - 4.3 [0.79]); Myasthenia Gravis Composite (-4.5 [2.63] and - 4.9 [1.19]); and Myasthenia Gravis Quality of Life 15-item questionnaire (-8.6 [5.68] and - 6.5 [1.93]). Overall, the safety of eculizumab was consistent with its known safety profile. In this interim sub-analysis, the efficacy and safety of eculizumab in Japanese and Caucasian patients were generally similar, and consistent with the overall REGAIN population.

Impact of Refractory Myasthenia Gravis on Health-Related Quality of Life

OBJECTIVES

Myasthenia gravis (MG) may be refractory to traditional therapies. Quality of life (QOL) and disease burden in patients with refractory and nonrefractory MG were compared using Myasthenia Gravis Foundation of America MG Patient Registry data.

METHODS

Adults aged 18 years or older with MG diagnosed ≥2 years before enrollment were included. Participants with refractory MG had received ≥2 previous and 1 current MG treatment and had MG Activities of Daily Living Scale total score ≥6 at enrollment; other participants had nonrefractory MG. MG QOL 15-item scale (MG-QOL15) scores were compared.

RESULTS

In total, 56 participants with refractory and 717 participants with nonrefractory MG enrolled. Participants with refractory MG had significantly higher mean (SD) MG-QOL15 total scores [31.4 (11.1) vs. 20.8 (15.0), P < 0.0001] and were more likely to have had exacerbations, emergency department visits, and recent hospitalizations.

CONCLUSIONS

Participants with refractory MG experience worse QOL and greater clinical burden than those with nonrefractory disease.

Myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or other AChR-related proteins in the postsynaptic muscle membrane. Localized or general muscle weakness is the predominant symptom and is induced by the antibodies. Patients are grouped according to the presence of antibodies, symptoms, age at onset and thymus pathology. Diagnosis is straightforward in most patients with typical symptoms and a positive antibody test, although a detailed clinical and neurophysiological examination is important in antibody-negative patients. MG therapy should be ambitious and aim for clinical remission or only mild symptoms with near-normal function and quality of life. Treatment should be based on MG subgroup and includes symptomatic treatment using acetylcholinesterase inhibitors, thymectomy and immunotherapy. Intravenous immunoglobulin and plasma exchange are fast-acting treatments used for disease exacerbations, and intensive care is necessary during exacerbations with respiratory failure. Comorbidity is frequent, particularly in elderly patients. Active physical training should be encouraged.