Well-controlled MG Linked to Better COVID-19 Outcomes in Small Study
Patients with well-controlled myasthenia gravis (MG) and no co-existing conditions, or comorbidities, are more likely to have milder COVID-19 and experience more favorable outcomes, according to a recent study.
“Our study has shown that COVID-19 does not necessarily have a severe course or poor outcome in MG patients. Absence of comorbidities and having well-controlled MG before infection likely affected the course of the infection favorably,” the researchers wrote, adding that these findings are “not surprising because infections and antibiotics are better tolerated in patients whose myasthenia is in remission or mild.”
The study, “Clinical Course and Outcome of an Outpatient Clinic Population with Myasthenia Gravis and COVID-19,” was published in the journal Muscle and Nerve.
Previous research has indicated that people with neuromuscular disorders such as MG might have an increased risk of severe disease and worse outcomes when faced with COVID-19.
In particular, those with generalized MG — a widespread form of the disease affecting several muscle groups — have weakened respiratory muscles and may require the use of immunosuppressants, which may further increase their risk of having a poor COVID-19 course, resulting in worse outcomes.
“Information obtained during the pandemic indicates that COVID-19 infection may have a more severe course in MG patients, and that these patients may need more intensive care support” when hospitalized, the researchers wrote.
However, previous studies focusing on MG patients with COVID-19 have mostly focused on hospitalized individuals — many of whom were intubated, or had a tube inserted into the airway to assist breathing. Mild cases were likely missed in these studies.
Now, researchers in Turkey reported on a small subset of MG patients who had COVID-19 and were seen in an outpatient clinic in Istanbul between March 1, 2020, and April 30, 2021. Vaccines against COVID-19 were not available at the time of the study.
The 19 patients were given questionnaires to assess the severity of COVID-19, and factors that might have contributed to its severity.
Among these patients, 17 had symptoms of COVID-19. One of the two patients with no symptoms (asymptomatic) tested positive on a COVID-19 PCR test without any family members having a positive test, and the other had a spouse with symptomatic COVID-19.
A total of 11 patients — nine women and two men — had mild cases of COVID-19 and did not require hospitalization. All but one had well-controlled MG with their scores on a measure of MG severity, called MGFA class, ranging from 0 (asymptomatic) to 2 (mild) prior to infection.
One woman had an MGFA class of 3a with weakness in the extremities, but no respiratory symptoms before infection. She also had Sjögren’s syndrome — an autoimmune condition affecting tear and saliva production — for which she was taking hydroxychloroquine, an immunosuppressant.
The investigators noted that the patients’ MG symptoms and medications were unaffected by COVID-19.
Across the entire group, 15 individuals were on immunosuppressants, such as prednisone and/or azathioprine, to treat their MG prior to contracting COVID-19.
All patients with mild COVID-19 had either no treatment for it or received the standard of care in Turkey at the time. One patient also received hydroxychloroquine for COVID-19. These 11 patients all made a full recovery.
Three patients had moderate COVID-19, which required hospitalization. They also made a full recovery.
“Increasing evidence suggests that immune suppression can play a protective role by reducing the immune response that leads to cytokine storm and clinical impairment. It is possible that increasing [corticosteroids] played a role in the recovery of three of our patients with moderate-severe COVID-19,” the researchers wrote.
Of the three patients with severe COVID-19, two had underlying co-existing diseases such as obesity, diabetes, and congestive heart failure. Both of these patients were intubated and ended up dying from COVID-19.
The third patient with severe COVID had two prostate surgeries one month prior to contracting the infection, after which he had a myasthenic exacerbation, an episode of sudden MG worsening in which the muscles that control breathing are affected.
“Those with more severe MG, particularly at the onset of infection, were reported to be more likely to have severe COVID-19,” the researchers wrote.
The three MG patients with severe COVID-19 were the oldest in the group, with ages ranging from 72 to 85. They also were the only ones with severe co-existing conditions.
“There were comorbidities such as obesity, advanced age, and others that could adversely influence progression of the disease,” the researchers wrote.
“It was not possible to separate the contribution of myasthenic weakness from that of respiratory involvement due to COVID-19 in these patients,” they wrote.
Overall, the death rate was about 10% among MG patients with COVID-19 in this study, the team noted.