COVID-19 Outcomes in Myasthenia Gravis Patients: Analysis From Electronic Health Records in the United States

Quantitatively assessing the impact of the quality of SNOMED CT subtype hierarchy on cohort queries

OBJECTIVE

SNOMED CT provides a standardized terminology for clinical concepts, allowing cohort queries over heterogeneous clinical data including Electronic Health Records (EHRs). While it is intuitive that missing and inaccurate subtype (or is-a) relations in SNOMED CT reduce the recall and precision of cohort queries, the extent of these impacts has not been formally assessed. This study fills this gap by developing quantitative metrics to measure these impacts and performing statistical analysis on their significance.

MATERIAL AND METHODS

We used the Optum de-identified COVID-19 Electronic Health Record dataset. We defined micro-averaged and macro-averaged recall and precision metrics to assess the impact of missing and inaccurate is-a relations on cohort queries. Both practical and simulated analyses were performed. Practical analyses involved 407 missing and 48 inaccurate is-a relations confirmed by domain experts, with statistical testing using Wilcoxon signed-rank tests. Simulated analyses used two random sets of 400 is-a relations to simulate missing and inaccurate is-a relations.

RESULTS

Wilcoxon signed-rank tests from both practical and simulated analyses (P-values < .001) showed that missing is-a relations significantly reduced the micro- and macro-averaged recall, and inaccurate is-a relations significantly reduced the micro- and macro-averaged precision.

DISCUSSION

The introduced impact metrics can assist SNOMED CT maintainers in prioritizing critical hierarchical defects for quality enhancement. These metrics are generally applicable for assessing the quality impact of a terminology's subtype hierarchy on its cohort query applications.

CONCLUSION

Our results indicate a significant impact of missing and inaccurate is-a relations in SNOMED CT on the recall and precision of cohort queries. Our work highlights the importance of high-quality terminology hierarchy for cohort queries over EHR data and provides valuable insights for prioritizing quality improvements of SNOMED CT's hierarchy.

Anti-cytokine autoantibodies: mechanistic insights and disease associations

Anti-cytokine autoantibodies (ACAAs) are increasingly recognized as modulating disease severity in infection, inflammation and autoimmunity. By reducing or augmenting cytokine signalling pathways or by altering the half-life of cytokines in the circulation, ACAAs can be either pathogenic or disease ameliorating. The origins of ACAAs remain unclear. Here, we focus on the most common ACAAs in the context of disease groups with similar characteristics. We review the emerging genetic and environmental factors that are thought to drive their production. We also describe how the profiling of ACAAs should be considered for the early diagnosis, active monitoring, treatment or sub-phenotyping of diseases. Finally, we discuss how understanding the biology of naturally occurring ACAAs can guide therapeutic strategies.

Rituximab as a sole steroid-sparing agent in generalized myasthenia gravis: Long-term outcomes

BACKGROUND

Rituximab, a B-cell depleting monoclonal antibody, represents an option for the treatment of refractory myasthenia gravis (MG). Its use is more established in muscle-specific tyrosine kinase positive (MuSK +) patients, while its role in managing acetylcholine receptor positive (AChR +), or double seronegative (DSN) patients, remains less clear. This study evaluates the long-term effectiveness and safety of rituximab in MG of various serotypes.

METHODS

We conducted an open-label study of MG patients receiving rituximab. Adults with generalized refractory MG, either anti-AChR + or DSN, and anti-MuSK + , refractory or not, who had follow-up > 12 months were selected. Change in quantitative myasthenia gravis (QMG) score at last follow-up, compared with baseline was a primary outcome, as well as factors affecting response to treatment. Secondary outcomes included, long-term safety, the steroid-sparing effect and relapse rates post-rituximab.

RESULTS

Thirty patients (16 anti-AChR + , 6 anti-MuSK + , 8 DSN) followed for a mean of 33.3 months were included. Mean scores pre-rituximab compared to last follow-up significantly decreased (p < 0.001), from 11 ± 4.1 to 4.3 ± 3.8, and from 1.9 to 0.3 regarding QMG and relapse rate per patient/year, respectively, while in 93.1% a daily steroid dose ≤ 10 mg was achieved. Antibody status was the only factor independently influencing several endpoints. Throughout the study period no crises or deaths occurred.

CONCLUSION

The present study supports that rituximab is an effective and well tolerated treatment for refractory anti-AChR + and DSN MG patients, while anti-MuSK + remains the group experiencing the greater benefits.

[Eculizumab led to beneficial clinical course in a patient with generalized myasthenia gravis who developed COVID 19-associated pneumonia]

A 74-year-old woman developed myasthenia gravis (MG) at the age of 32. She had a thymoma removed the following year, but her MG symptoms did not stabilize, and she required frequent hospitalization for fast-acting treatment (FT). She started eculizumab in March of two years ago and was followed up on an outpatient basis as her MG symptoms became milder. In February of this year, she was admitted to our hospital due to mild COVID-19-associated pneumonia with general malaise and fever. Her COVID-19-associated pneumonia was treated with intravenous sotrovimab, dexamethasone, and unfractionated heparin, and oral therapy for MG stayed the same. Eculizumab was not administered during hospitalization due to the combination of stable MG symptoms and the fact that the drug is not paid for by the Japanese insurance system. The patient's MG and COVID-19-associated pneumonia were not severe during hospitalization. However, the risk of myasthenic crisis and death is high when patients with MG develop COVID-19-associated pneumonia. Several reports suggest that the condition of patients with eculizumab-treated MG who develop COVID-19-associated pneumonia is not severe, and that that inhibition of the complement pathway with eculizumab is effective for COVID-19-associated pneumonia. Complement deposition in organ microvessels has been observed in patients with COVID-19, which suggests that complement overload may be a risk factor for COVID-19-associated pneumonia. Excessive complement activation may be involved in the pathogenesis; thus, eculizumab may function by inhibiting this pathway. In this case, eculizumab was discontinued while the patient had COVID-19-associated pneumonia, however, CH50, which is an indicator of complement, was suppressed during hospitalization due to the COVID-19-associated pneumonia. Therefore, eculizumab may have interfered with this course of events. This case demonstrates that eculizumab may be safe for and tolerated by patients with MG and COVID-19-associated pneumonia, but more cases need to be accumulated to support this conclusion.

Ravulizumab in Myasthenia Gravis: A Review of the Current Evidence

The terminal complement C5 inhibitor ravulizumab was engineered from the humanized monoclonal antibody eculizumab to have an extended half-life and duration of action. It binds to human terminal complement protein C5, inhibiting its cleavage into C5a and C5b, thus preventing the cascade of events that lead to architectural destruction of the postsynaptic neuromuscular junction membrane by the membrane attack complex, and consequent muscle weakness in patients with anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG). The 26-week randomized, placebo-controlled period (RCP) of the phase 3 CHAMPION MG study demonstrated the rapid efficacy of ravulizumab in reducing MG symptoms. Weight-based dosing of ravulizumab every 8 weeks provided sustained efficacy, in terms of patient-reported (Myasthenia Gravis-Activities of Daily Living) and clinician-reported (Quantitative Myasthenia Gravis) endpoints in patients with anti-AChR antibody-positive gMG. Pharmacokinetic and pharmacodynamic analyses showed therapeutic serum ravulizumab concentrations (>175 µg/mL) were achieved immediately after the first dose and were maintained throughout 26 weeks, irrespective of patient body weight; inhibition of serum free C5 was immediate, complete (<0.5 μg/mL), and sustained in all patients. Interim results from the open-label extension (OLE) showed that after 60 weeks, efficacy was maintained in patients continuing on ravulizumab. Rapid and sustained improvements in efficacy, similar to those seen in patients initiating ravulizumab in the RCP, were observed after initiation of ravulizumab treatment in patients who switched from placebo in the RCP to ravulizumab in the OLE. The findings from the RCP and OLE support ravulizumab's favorable safety profile. In conclusion, ravulizumab has a simple weight-based administration and long dosing interval. Its targeted mechanism of action without generalized immunosuppression is reflected in its rapid onset of symptom improvement, sustained efficacy and good safety profile in the treatment of patients with anti-AChR antibody-positive gMG.

Anti-SARS-CoV-2 (COVID-19) vaccination efficacy in patients with severe neuromuscular diseases

INTRODUCTION

Patients with severe neuromuscular disease (sNMD) are considered at high risk of severe COVID-19. Muscle tissue is often replaced by fibroadipose tissue in these diseases whereas the new mRNA-based vaccines are injected intramuscularly. We aimed at evaluating the efficacy of two injections associated with a booster injection of mRNA vaccine in these patients.

METHODS

We performed an observational, prospective, single-centre study to investigate the level of anti-S antibodies (Abs) and their neutralization activity at weeks 6 (W6) and 24 (W24) after two injections of mRNA-1273 vaccine and at weeks 12 (BW12) and 29 (BW29) after a booster injection of BNT162b2 vaccine in patients with sNMD.

RESULTS

Thirty-three patients with sNMD were included. At W6, 30 patients (90.1%) showed a protective serum level of specific anti-S Abs with a strong neutralization capacity. We observed a decline over time: only 12 patients (36.3%) retained anti-S Abs levels considered as protective at W24. The neutralization activity remained above the cut off in 23 (69.7%). The booster vaccination restored robust neutralization activity for all analysed 22 patients (100%) at BW12, which was maintained without any significant drop at BW29 (16). No severe adverse event was reported in this cohort and none of the 33 patients developed symptomatic COVID-19 over one year.

CONCLUSIONS

This study provides evidence that most sNMD patients receiving two injections of COVID-19 mRNA-based vaccines develop a strong humoral response after vaccination. A decline over time was observed but a single booster injection restores a long-term immunity. Moreover, no safety issues were observed.

COVID-19 infection in myasthenia gravis: Clinical course and outcomes

INTRODUCTION/AIMS

Myasthenia gravis (MG) patients have been predicted to have high rates of coronavirus disease-2019 (COVID-19) complications due to frequent involvement of respiratory muscles in MG and frequent use of immunosuppressive therapies. We investigated outcomes of MG patients infected with SARS-CoV-2 to identify risk factors for exacerbation and severe disease.

METHODS

This was a retrospective analysis of 39 MG patients with SARS-CoV-2 infection from January March 1, 2020 to October 25, 2021 at Emory University. Patients' records were queried for demographic data, MG history, and COVID-19 treatments and hospitalizations.

RESULTS

At the time of infection, 8 of 39 were vaccinated, 30 of 39 unvaccinated, and 1 unknown. Average age was 52.6 years. Twenty-seven patients were receiving immunomodulatory treatments at the time of infection. Thirty-five of 39 were symptomatic, 21 were hospitalized, and 7 required ventilations. MG exacerbations occurred in 5 and were treated with therapeutic plasma exchange (n = 1), intravenous immunoglobulin (IVIg) (n = 1), and prednisone taper (n = 5). Four hospitalized patients died from COVID-related lung injuries. No deaths were attributed to MG exacerbation; however, one patient receiving IVIg for MG exacerbation had a pulmonary embolism. There were no deaths in fully vaccinated patients, and only one vaccinated patient was admitted to the intensive care unit.

DISCUSSION

High rates of COVID-19 complications and death were observed in this cohort of MG patients. Some patients with MG and COVID-19 also had an exacerbation during infection. Further studies are needed to determine whether MG patients are at higher risk for complications than the rest of the population.

Neuromuscular Disorders Associated With COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has had an enormous impact on practically every aspect of daily life, and those with neuromuscular disorders have certainly not been spared. The effects of COVID-19 infection are far-reaching, going well beyond respiratory symptoms alone. From simple myalgias to debilitating critical illness neuromyopathies, we continue to learn and catalog the diverse pathologies presented by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as it relates to the neuromuscular system. Complications have been documented both as a direct result of primary infection but also in those with pre-existing neuromuscular disorders from myasthenia gravis to devastating critical illness neuromyopathies. In this review, we will discuss the relationship between COVID-19 infection and critical illness neuromyopathy, peripheral nerve palsies, myalgias, positional compressive neuropathy, myasthenia gravis, and Guillain-Barré syndrome.

Temporal Cohort Logic

We introduce a new logic, called Temporal Cohort Logic (TCL), for cohort specification and discovery in clinical and population health research. TCL is created to fill a conceptual gap in formalizing temporal reasoning in biomedicine, in a similar role that temporal logics play for computer science and its applications. We provide formal syntax and semantics for TCL and illustrate the various logical constructs using examples related to human health. Relationships and distinctions with existing temporal logical frameworks are discussed. Applications in electronic health record (EHR) and in neurophysiological data resource are provided. Our approach differs from existing temporal logics, in that we explicitly capture Allen's interval algebra as modal operators in a language of temporal logic (rather than addressing it in the semantic structure). This has two major implications. First, it provides a formal logical framework for reasoning about time in biomedicine, allowing general (i.e., higher-levels of abstraction) investigation into the properties of this approach (such as proof systems, completeness, expressiveness, and decidability) independent of a specific query language or a database system. Second, it puts our approach in the context of logical developments in computer science, allowing potential translation of existing results into the setting of TCL and its variants or subsystems so as to illuminate opportunities and computational challenges involved in temporal reasoning for biomedicine.

Myasthenic crisis

Myasthenic crisis (MC) is a life-threatening manifestation of myasthenia gravis (MG) defined by respiratory insufficiency that requires the use of invasive or non-invasive ventilation. This is often the result of respiratory muscle weakness but can also be due to bulbar weakness with upper airway collapse. MC occurs in approximately 15%-20% of patients with MG usually within the first 2 to 3 y of the disease course. Many crises have a specific trigger with respiratory infections being most common; however, no specific trigger is found in 30%-40% of patients. MG patients with a history of MC, severe disease, oropharyngeal weakness, muscle-specific kinase (MuSK) antibodies and thymoma appear to be at higher risk. Most episodes of MC do not occur suddenly, providing a window of opportunity for prevention. Immediate treatment is directed toward airway management and removing any identified triggers. Plasmapheresis is preferred over intravenous immune globulin as the treatments of choice for MC. The majority of patients are able to be weaned from mechanical ventilation within 1 mo and the outcomes of MC are generally favorable. The mortality rate in United States cohorts is less than 5% and mortality in MC seems to be driven by age and other medical co-morbidities. MC does not appear to affect long-term prognosis as many patients are able to eventually achieve good MG control.

Neuromuscular Complications of COVID-19: Evidence from the Third Year of the Global Pandemic

Accumulating evidence in the third year of the global pandemic suggests that coronavirus disease 2019 (COVID-19) can cause neuromuscular complications during or after the acute phase of infection. Direct viral infection and immune-mediated mechanisms have been hypothesized. Furthermore, in patients with underlying autoimmune neuromuscular diseases, COVID-19 infection may trigger a disease flare. COVID-19 vaccines appear to be safe and effective at preventing severe illness from COVID-19. Certain vaccines are associated with an increased risk of Guillain-Barré syndrome and possibly Bell's palsy, but the absolute incidence is low, and benefits likely outweigh the risks. Newer prophylactic therapies and treatments are also becoming available for patients who may not mount a sufficient response to vaccination or have contraindications. In this article, we discuss the current available evidence on neuromuscular complications of COVID-19 and clinical considerations regarding vaccination.

Case Report: Functional Outcome of COVID-19 Subjects With Myasthenia Gravis and Critical Illness Polyneuropathy

Background

The COVID-19 disease can affect subjects suffering from myasthenia gravis (MG) and worsen its clinical course, leading to intensive care unit (ICU) admission. Critically ill subjects can develop a neuromuscular complication called ICU-acquired weakness (ICUAW). This disorder has also been detected in ICU subjects with COVID-19, but the association between MG and ICUAW has never been described in critically ill patients. We describe the case and functional outcome of a COVID-19 patient suffering from MG who developed critical illness polyneuropathy (CIP).

Case Presentation

A 66-year-old man with a history of hypertension and ocular MG had COVID-19 and required ICU admission. The patient underwent mechanical ventilation and tracheotomy and was treated with remdesivir and corticosteroids. Fifteen days after admission, he complained of tetraparesis without the ocular involvement that remained unchanged despite the increase in anticholinesterase therapy. The length of stay (LOS) in ICU was 35 days. On day 2 of admission, the patient underwent a frontal muscle jitter study that confirmed the MG, and electroneurography (ENG) and electromyography (EMG) that showed overlapping ICUAW with electrophysiological signs characteristic of CIP. The cerebrospinal fluid (CSF) showed normal pressure, cell count, and protein levels (&lt;45 mg/dl) without albumin-cytologic disassociation. The CSF/serum glucose ratio was normal. The CSF culture for possible organisms, laboratory tests for autoimmune disorders, the panel of antiganglioside antibodies, and the paraneoplastic syndrome were negative. Strength and functional outcomes were tested with the MRC scale, the DRS, Barthel scale, and the Functional Independence Measure (FIM) at admission, discharge, and follow-up. Muscular strength improved progressively, and the MRC scale sum-score was 50 at discharge. Anticholinesterase therapy with pyridostigmine at a dosage of 30 mg 3 times daily, which the patient was taking before COVID-19, was resumed. His motor abilities recovered, and functional evaluations showed full recovery at follow-up.

Conclusion

In the described subject, the coexistence of both neuromuscular disorders did not affect the clinical course and recovery, but the question remains about generalization to all patients with MG. The rehabilitation interventions might have facilitated the outcome.