Prevalence and risk factors of myasthenia gravis recurrence post-thymectomy

Constructing and Validating a Nomogram Model for Short-Term Prognosis of Patients with AChR-Ab+ GMG

OBJECTIVE

This study aimed to establish and validate a nomogram prognostic model for predicting short-term efficacy of acetylcholine receptor antibody-positive (AChR-Ab+) generalized myasthenia gravis (GMG).

METHODS

A retrospective observational study was conducted at the First Hospital of Shanxi Medical University, enrolling patients diagnosed with AChR-Ab+ GMG from May 2020 to September 2022. The primary outcome was the change in the Myasthenia Gravis Foundation of America (MGFA) post-intervention status after 6 months of standard treatment. Predictive factors were identified through univariate and multivariate logistic regression analyses, with significant factors incorporated into the nomogram. The bootstrap test was used for internal validation of the nomogram model. Model performance was assessed using calibration curves, receiver-operating characteristic curve analysis, and decision curve analysis (DCA).

RESULTS

A total of 90 patients were enrolled, of whom 30 achieved unchanged or worse status after 6 months of standard therapy. Univariate logistic regression analysis showed that quantitative myasthenia gravis score, gender, body mass index, course of disease, hemoglobin levels, and white blood cell counts were six potential predictors. These factors were used for multivariate logistic regression analysis, and a nomogram was constructed. The calibration curve showed that the predicted value was in good agreement with the actual value (p = 0.707), and the area under the curve value (0.792, 95% CI 0.686-0.899) indicated good discrimination ability. DCA suggests that this model has potential clinical application value.

CONCLUSION

The constructed nomogram, based on key patient indicators, shows promise as a clinically useful tool for predicting the short-term efficacy of treatment of AChR-Ab+ GMG. Validation in larger, multicenter cohorts is needed to further substantiate its applicability.

The rate of QMGS change predicts recurrence after thymectomy in myasthenia gravis

OBJECTIVE

To investigate the relationship between short-term changes in quantitative myasthenia gravis score (QMGS) after thymectomy and postoperative recurrence in myasthenia gravis (MG) patients without thymoma.

METHODS

A retrospective observational cohort study. The QMGS of 44 patients with non-thymomatous MG were evaluated before and 1 month after thymectomy, and the frequency and time of postoperative recurrence were recorded. The reduction rate of QMGS (rr-QMGS) was defined as (QMGS one week before thymectomy - QMGS one month after thymectomy)/ QMGS one week before thymectomy × 100 %, as an indicator of short-term symptom change after thymectomy. The receiver operating characteristic (ROC) curve was established to determine an appropriate cut-off value of rr-QMGS for distinguishing postoperative recurrence. Multivariate Cox regression analysis was applied to predict postoperative recurrence.

RESULTS

Postoperative recurrence occurred in 21 patients (30 times in total) during follow-up. The mean annual recurrence rate was 3.98 times/year preoperatively and 0.30 times/year postoperatively. ROC analysis determined the cut-off value of rr-QMGS was 36.7 % (sensitivity 90.5 %, specificity 52.2 %). Multivariate Cox regression analysis showed that rr-QMGS＜36.7 % (hazard rate[HR]6.251, P = 0.014) is positive predictor of postoperative recurrence. Kaplan-Meier analysis showed that postoperative recurrence time was earlier in the low rr-QMGS group than in the high rr-QMGS group (12.62 vs. 36.60 months, p = 0.005).

CONCLUSIONS

Low rr-QMGS is associated with early postoperative recurrence. Rr-QMGS can be used to predict postoperative recurrence of non-thymomatous MG.

Association between COVID-19 and myasthenia gravis (MG): A genetic correlation and Mendelian randomization study

BACKGROUND

Observational studies have suggested an association between coronavirus disease 2019 (COVID-19) and myasthenia gravis (MG). Here, we aimed to estimate the genetic correlation and causal relationship between COVID-19 susceptibility, hospitalization, severity, and MG phenotypes using linkage disequilibrium score regression (LDSC) and Mendelian randomization (MR) approach.

METHODS

Summary statistics of COVID-19 susceptibility, hospitalization, and severity were used as instrumental variables for exposure traits. Large-scale genome-wide association study (GWAS) data for MG were used as outcome traits. The inverse variance weighted approach was used for the main MR analysis, complemented by MR-Egger, weighted median, simple mode, and weighted mode methods. Sensitivity analysis was implemented using Cochran's Q test, MR-PRESSO method, and MR-Egger intercept test.

RESULTS

LDSC analysis did not reveal any genetic correlation among COVID-19 susceptibility, hospitalization, severity, and MG phenotypes, including MG, early-onset MG, and late-onset MG (p > .05). Our MR analysis did not provide evidence supporting a causal effect of COVID-19 susceptibility, hospitalization, or severity on MG phenotypes (p > .05). Extensive sensitivity analysis strengthened the robustness and consistency of the MR estimates.

CONCLUSION

Our study did not find evidence of a genetic correlation or causal relationship among COVID-19 susceptibility, hospitalization, severity, and MG. Future studies with more GWAS data are needed to evaluate the association between COVID-19 phenotypes and MG and its subgroups.

Circulating miRNAs drive personalized medicine based on subgroup classification in myasthenia gravis patients

Myasthenia gravis (MG) is a classic autoimmune neuromuscular disease with strong clinical heterogeneity. The concept of subgroup classification was proposed to guide the precise treatment of MG. Subgroups based on serum antibodies and clinical features include ocular MG, early-onset MG with AchR antibodies, late-onset MG with AchR antibodies, thymoma-associated MG, MuSK-associated MG, LRP4-associated MG, and seronegative MG. However, reliable objective biomarkers are still needed to reflect the individualized response to therapy. MicroRNAs (miRNAs) are small non-coding RNA molecules which can specifically bind to target genes and regulate gene expression at the post-transcriptional level, and then influence celluar biological processes. MiRNAs play an important role in the pathogenesis of autoimmune diseases, including MG. Several studies on circulating miRNAs in MG have been reported. However, there is rare systematic review to summarize the differences of these miRNAs in different subgroups of MG. Here, we summarize the potential role of circulating miRNAs in different subgroups of MG to promote personalized medicine.

Subxiphoid and subcostal arch versus unilateral video-assisted thoracic surgery approaches to thymectomy for myasthenia gravis

PURPOSE

Thymectomy is an important treatment for myasthenia gravis (MG). We conducted this study to compare the clinical outcomes of the recently introduced subxiphoid and subcostal arch thymectomy (SASAT) approach with those of the standard unilateral video-assisted thoracoscopic surgery (VATS).

METHODS

We analyzed, retrospectively, the perioperative, and long-term outcomes of 179 consecutive MG patients (age 18-65 years), who underwent SASAT or unilateral VATS-extended thymectomy between July, 2012 and May, 2019.

RESULTS

All demographic and clinical characteristics were comparable in the two groups. The median surgical time, estimated blood loss, thoracotomy conversion rate, total and chest drainage, and complications did not differ significantly between the groups. The visual analog scale (VAS) score was significantly lower in the SASAT group. Complete stable remission (CSR) was achieved in a significantly larger proportion of the SASAT group patients and was significantly higher in women than in men. The Quantitative MG score was significantly lower in the SASAT group. Patients in the MG Foundation of America Clinical Classification groups I and II achieved better remission rates than those in groups III-V.

CONCLUSIONS

SASAT is a safe and feasible MG treatment, which may yield better outcomes than unilateral VATS and improve the quality of treatment.

Early Flare-Ups of Myasthenia Gravis After Thoracoscopic Thymectomy in a Patient Recently Receiving BNT162b2 mRNA COVID-19 Vaccination

Myasthenia gravis (MG) is an autoimmune disorder characterized by abnormal neuromuscular transmission. The thymus is believed to play a key role in the pathogenesis of MG, and thymectomy has been an optional treatment for the disease. Relapse of MG after thymectomy has been reported. Exacerbations and new onset of MG following COVID-19 vaccination have also been documented. This report presents a case of a stable MG patient with recent COVID-19 vaccination experiencing flare-ups of symptoms shortly after video-assisted thoracoscopic (VATS) thymectomy. A 31-year-old female received the second dose of the BNT162b2 mRNA COVID-19 vaccine eight days before thymectomy and developed flare-ups of symptoms four days after the surgery. Although the substantial link between MG exacerbations post-thymectomy and pre-thymectomy COVID-19 vaccination cannot be concluded, this observation warrants further research.