Sensitivity of MG-ADL for generalized weakness in myasthenia gravis

Anti-dsDNA Is Associated with Favorable Prognosis in Myasthenia Gravis: A Retrospective Study

Objectives. To investigate the presence of serum antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-dsDNA) in patients with myasthenia gravis (MG) and analyze the clinical characteristics and prognostic factors associated with MG. Methods. We retrospectively enrolled 363 patients with MG and analyzed the clinical characteristics and follow-up data between patients positive and negative for ANA and anti-dsDNA. We defined a Myasthenia Gravis Activities of Daily Living (MG-ADL) reduction as a main prognosis predictor and used logistic regression to determine independent factors associated with prognosis. We built a nomogram to predict prognosis and evaluate the internal validity of the model. Results. Ninety-eight (27.0%) patients were positive for ANA, and 51 (14.0%) were positive for anti-dsDNA. Patients positive for ANA and anti-dsDNA antibodies tended to be female and positive for acetylcholine receptor antibody (AChR-Ab). The rate of thymoma was higher in anti-dsDNA-positive patients with MG (p-dsDNA-MG) than in patients negative for anti-dsDNA (49.0% vs. 26.0%, $p=0.001$ ), and p-dsDNA-MG was associated with reduced MG-ADL score. Regression analysis showed that except for age of onset ( $\text{OR}=0.986$ , $95\%\text{CI}=0.973–0.999$ , $p=0.037$ ), anti-dsDNA ( $\text{OR}=2.800$ , $95\%\text{CI}=1.381–5.679$ , $p=0.004$ ), ptosis ( $\text{OR}=2.930$ , $95\%\text{CI}=1.827–4.699$ , $p<0.001$ ), and eye movement disorder ( $\text{OR}=2.815$ , $95\%\text{CI}=1.672–4.741$ , $p<0.001$ ) were independent predictive factors of a favorable prognosis of MG. These predictors were used to generate a nomogram with an excellent predictive value. Conclusions. Being female and the presence of AChR-Ab were features of ANA- or anti-dsDNA-positive MG. The presence of anti-dsDNA was associated with a favorable prognosis of MG.

Short-term outcome prediction for myasthenia gravis: an explainable machine learning model

Background

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatigability. The fluctuating nature of the disease course impedes the clinical management.

Objective

The purpose of the study was to establish and validate a machine learning (ML)-based model for predicting the short-term clinical outcome in MG patients with different antibody types.

Methods

We studied 890 MG patients who had regular follow-ups at 11 tertiary centers in China from 1 January 2015 to 31 July 2021 (653 patients for derivation and 237 for validation). The short-term outcome was the modified post-intervention status (PIS) at a 6-month visit. A two-step variable screening was used to determine the factors for model construction and 14 ML algorithms were used for model optimisation.

Results

The derivation cohort included 653 patients from Huashan hospital [age 44.24 (17.22) years, female 57.6%, generalized MG 73.5%], and the validation cohort included 237 patients from 10 independent centers [age 44.24 (17.22) years, female 55.0%, generalized MG 81.2%]. The ML model identified patients who were improved with an area under the receiver operating characteristic curve (AUC) of 0.91 [0.89-0.93], 'Unchanged' 0.89 [0.87-0.91], and 'Worse' 0.89 [0.85-0.92] in the derivation cohort, whereas identified patients who were improved with an AUC of 0.84 [0.79-0.89], 'Unchanged' 0.74 [0.67-0.82], and 'Worse' 0.79 [0.70-0.88] in the validation cohort. Both datasets presented a good calibration ability by fitting the expectation slopes. The model is finally explained by 25 simple predictors and transferred to a feasible web tool for an initial assessment.

Conclusion

The explainable, ML-based predictive model can aid in forecasting the short-term outcome for MG with good accuracy in clinical practice.

Outcomes and characteristics of myasthenia gravis: A 10-year retrospective cross-sectional study at King Fahad Medical City

OBJECTIVES

To investigate the distribution of muscle weakness in Myasthenia gravis (MG) and the therapeutic response in each category.

METHODS

This is a retrospective cross-sectional study included all MG patients presented to our clinic between 2010 and 2020. The demographic, clinical, serological, electrophysiological, radiological, and histopathological data of the patients were recorded. The details of the treatment administered were also documented. Muscle weakness was divided into: ocular, bulbar, and generalized.

RESULTS

The mean age of the 147 patients included in this study was 34.2±16.6 years. The most common presentation was ocular MG (57.1%). There was no significant association between the gender of the patients and the MG subgroups. Antibodies against AChR were reported in 95.2%, 75%, and 87% of the patients with ocular, bulbar, and generalized myasthenia, respectively. Anti-MuSK antibodies were detected in 20% of the patients with bulbar weakness. Most of the patients with ocular (91.7%) and bulbar (90%) presentation developed generalized weakness. At the end of the follow-up, 82.6%, 70.2%, and 57.5% of the patients with generalized, ocular, and bulbar presentations, respectively demonstrated well-controlled weakness.

CONCLUSION

The most common initial presentation was ocular weakness. Most patients with ocular and bulbar presentation developed generalized weakness during the follow up period. The most frequently reported autoantibody was against AChR. Most patients with generalized, ocular, and bulbar presentation demonstrated well-controlled weakness at the end of the follow up period.

Different Monoclonal Antibodies in Myasthenia Gravis: A Bayesian Network Meta-Analysis

Background: Myasthenia gravis (MG) is a common autoimmune disease with acquired neuromuscular transmission disorders. Recently, monoclonal antibodies have been shown to successfully treat a variety of diseases.

Methods: In this meta-analysis, an appropriate search strategy was used to search eligible randomized controlled trials (RCTs) on different monoclonal antibodies to treat patients with MG published up to September 2021 from the embase, PubMed, and Cochrane Library. We assessed the average difference or odds ratio between each drug and placebo and summarized them as the average and 95% confidence interval (CI), respectively.

Results: In indicators of efficacy, patients receiving eculizumab (MD, −1.9; 95% CI, −3.2–0.76) had decreases in MG-ADL scores compared to placebo. In addition, only eculizumab (MD, −3.1; 95% CI, −4.7–1.5) and efgartigimod (MD, −1.4; 95% CI, −2.1–0.68) showed a significant difference from placebo in the amount of reduction in QMG scores, while neither of the other two monoclonal antibodies was statistically significant. With regard to the safety of monoclonal antibody therapy, there was no significant difference in the probability of AE in subjects treated with any of the four monoclonal antibodies compared to placebo.

Conclusions: eculizumab was effective in reducing MG-ADL scores and QMG scores in myasthenia gravis. Meanwhile, eculizumab also caused fewer AE. As an emerging therapy, monoclonal antibodies are prospective in the treatment of MG. However, more researches are required to be invested in the future as the results obtained from small sample sizes are not reliable enough.

Free-Living Physical Activity and Sedentary Behaviour in Autoimmune Myasthenia Gravis: A Cross-Sectional Study

BACKGROUND

Muscle weakness and fatigability, the prominent symptoms of autoimmune myasthenia gravis (MG), negatively impact daily function and quality of life (QoL). It is currently unclear as to what extent symptoms limit activity and whether physical activity (PA) behaviours are associated with reduced QoL.

OBJECTIVES

This study aimed to describe habitual PA patterns and explore relationships between PA metrics, clinical MG characteristics, and health-related QoL (HRQoL).

METHODS

PA data from a tri-axial trunk accelerometer worn for seven days, was collected from females with generalized, stable MG and compared to control subjects. MG-specific evaluations, the six-minute walk test and knee extension strength were assessed in individuals with MG (IwMG). Mann-Whitney tests were used to study between-group differences. Spearman rank correlation coefficient was performed to explore relationships between variables.

RESULTS

Thirty-three IwMG (mean (SD) age 45 (11) years) and 66 control subjects were included. IwMG perform less vigorous-intensity PA than control subjects (p = 0.001), spend more time sedentary (p = 0.02) and engage in less and shorter durations of moderate-vigorous-intensity PA (MVPA). For IwMG, habitual PA correlated positively with 6 min walking distance (rho = 0.387, p = 0.029) and negatively with body mass index (rho = -0.407, p = 0.019). We did not find any association between PA or sedentary behaviour and; HRQoL, symptom severity nor lower limb strength.

CONCLUSIONS

Individuals with stable MG perform less PA, at lower intensities, and are more inactive than control individuals. Further research is warranted to understand factors influencing PA patterns in MG and whether interventions could be successful in increasing PA quantity and intensity in IwMG.

Gender differences in clinical outcomes in myasthenia gravis: A prospective cohort study

INTRODUCTION/AIMS

It is uncertain whether clinical outcomes differ between male and female patients with myasthenia gravis (MG) while receiving standard clinical care.

METHODS

In a prospective cohort study of 107 patients with MG receiving standard of care from 2012 to 2019, the Quantitative MG (QMG), the MG Composite (MGC), the MG Activities of Daily Living (MG-ADL), and the MG Quality of Life 15-Items (QOL15) were determined. Clinical outcomes were analyzed in relation to gender.

RESULTS

Mean follow-up time was 4.8 (±0.4) y, and 70 patients completed all follow-up assessments. Patients improved on all clinical scores: QMG -1.8 (P < .001), MGC -1.5 (P < .001), MG-ADL -1.3 (P < .001), and QOL15 -3.0 (P < .001). Females improved less than males on the QMG (P = .01), MGC (P < .001), MG-ADL (P = .006), and QOL15 (P < .001) independent of potential confounders. Males had moderate to strong correlations between changes in all clinical scales (r range 0.52 to 0.73), whereas females had weak correlations between changes in the QMG and MG-ADL (r = 0.13), the QMG and QOL15 (r = 0.27), the MGC and MG-ADL (r = 0.21), the MGC and QOL15 (r = 0.00), and the MG-ADL and QOL15 (r = 0.31).

DISCUSSION

Females improved less compared to males on objective and patient-reported outcomes. Moreover, females improved more on objective measures than on patient-reported outcomes. These gender differences should receive attention in clinical care and in the design of future trials.

In-depth peripheral CD4+ T profile correlates with myasthenic crisis

Objective

Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies against neuromuscular junctions. Myasthenic crisis (MC) represents the most severe state of MG with high in‐hospital mortality. We aimed to identify immune signatures using in‐depth profiling in MC, and to assess the correlations between immune biomarkers with clinical severity longitudinally.

Methods

We studied 181 participants including 57 healthy controls, 96 patients with MG who never experienced crisis and 28 MC patients from December 2018 through June 2020. Follow‐up visits occurred prospectively from crisis to 6 months off‐mechanical ventilation. The frequencies of 20 CD4⁺ T subpopulations and 18 serum cytokines were associated with clinical scores using correlations and principal component analysis.

Results

Patients in crisis exhibited a proinflammatory CD4⁺T response with elevated Th1 (P = 0.026), and Th17 cells (P = 0.032); decreased T follicular helper 2 (Tfh2) cells (P < 0.001), Tnaive in Tfh cells (P < 0.001), ICOS⁻Tfh cells (P = 0.017), and T central memory in Tfh (P = 0.022) compared with controls, and increased frequencies of Tregs (P = 0.026) and Tfh17 (P = 0.045) compared with non‐crisis MG. Cytokine cascade was identified in crisis including the ones associated with Th1 (IL‐1β/2/12p70/18/27/IFN‐γ/TNF‐α), Th2 (IL‐4/5/13), Th17 (IL‐6/17A/21/22/23/GM‐CSF), Th9 (IL‐9), and Treg (IL‐10). Longitudinally, seven immune biomarkers including Tregs, IL‐2/4/17A/IFN‐γ/TNF‐α/GM‐CSF had significant correlations with MG‐activities of daily living score.

Interpretation

Vigorous inflammatory CD4⁺ T signatures were identified in MC and are associated with clinical severity. Future research is needed to explore its potential candidacy for therapeutic intervention and predicting impending crisis.

Pharmacodynamic Properties of Subcutaneous Immunoglobulin in Myasthenia Gravis: Sub-analyses From an Open-Label Trial

Background: We previously reported an open-label prospective trial of subcutaneous immunoglobulin (SCIg) in mild to moderate exacerbations of myasthenia gravis (MG). The effective dose of SCIg in MG and whether measured immunoglobulin G (IgG) levels correlated with measures of disease burden were not reported.

Objectives: To understand the relationship between SCIg dosing and serum IgG levels on measures of disease burden: quantitative MG (QMG), MG activities of daily living (MG-ADL), MG composite (MGC), and manual muscle testing (MMT) scores.

Methods: We performed post-hoc analyses of variance to assess change in oculobulbar and generalized sub-scores. We assessed the improvement in QMG, MG-ADL, MGC, or MMT over intervals from baseline to week 2, weeks 2–4, and week 4 to end of study. Improvement was either greater than (coded 1) or was equal to or less than (coded 0) the previous 2 weeks. Binaries were assessed in binary logistic regression as a function of SCIg dose over the two-week interval as the independent variable. We also performed linear regression analyses with change in the clinical scores as the dependent variable and change in IgG level over the entire study period and over the interval from weeks 2 to 4, during which change in IgG level was maximal, as the independent variables.

Results: Subanalysis of QMG and MG-ADL scores demonstrated significant reductions in the oculobulbar and the generalized portions of both measures. Binary logistic regression analyses did not find any statistically significant correlations between the odds of improvement and weight-adjusted dose of SCIg over 2-week intervals. There were no significant relationships between changes in scores and IgG level over the entire study period or over the interval from weeks 2 to 4.

Conclusions: Although SCIg dose varied over the study period, the odds of improvement were not significantly correlated with this, which suggests that the current dose of 2 g/kg for SCIg should be compared to different, possibly lower, dosing regimens head-to-head. The change in clinical scores was not significantly associated with IgG levels suggesting a complex relationship. SCIg may be effective for both ocular and generalized presentations of MG.

Myasthenia Gravis Impairment Index: Sensitivity for Change in Generalized Muscle Weakness

INTRODUCTION

The recently developed Myasthenia Gravis Impairment Index (MGII) is a promising measure as it has less floor effects and a higher relative efficiency in its responsiveness to treatment effect compared to other MG measures. This study aimed at validating the MGII in a Dutch cohort of MG patients and analyzing the sensitivity of MGII compared to MG-ADL for changes in generalized weakness.

METHODS

We analyzed (generalized items of; -gen) MGII, quantitative myasthenia gravis (QMG), Myasthenia Gravis Activities of Daily Living (MG-ADL), EQ-5D visual analog, Myasthenia Gravis Composite (MGC) and ACTIVLIM (an ADL questionnaire focusing on generalized weakness) scores in a prospective cohort of 99 MG patients. We investigated correlations between MGII and other outcome measures. We used a generalized linear model to assess whether MGIIgen had an additional sensitivity on top of MG-ADLgen for changes (Δ) in QMGgen in individual patients.

RESULTS

MGII had a lower floor effect (4%) compared to QMG (6%), MG-ADL (11%) and MGC (16%). MGII correlated well with QMG (r = 0.68), MG-ADL (r = 0.83) and MGC (r = 0.74). As expected, the correlations with EQ visual analog and ACTIVLIM were lower (r = - 0.57 and - 0.48). ΔMGIIgen had an additional value on top of ΔMG-ADLgen in the prediction of ΔQMGgen (B = 0.54, p = 0.01).

DISCUSSION

The MGII score was cross-culturally validated in a Dutch cohort of MG patients. MGII had a higher sensitivity for generalized weakness than MG-ADL.