IC risk factors from myasthenia gravis exacerbation seen in study
Admission risk twice as high among women, nearly 5X in those with thymoma
Myasthenia gravis (MG) patients who are women or have a tumor in the thymus gland are more likely to require intensive care due to disease exacerbation, a retrospective study in Finland suggests.
Patients with late-onset disease in whom disease symptoms become apparent after the age of 50 were also more likely to need intensive care, the study found.
“Special attention to early treatment choices should therefore be given, especially in [late-onset MG] patients,” the researchers wrote. “However, only 6% of [people with MG] were ever in need of intensive care in our hospital district, emphasizing the rarity of this life-threatening event.”
The study, “Intensive care due to myasthenia gravis: Risk factors and prognosis,” was published in the European Journal of Neurology.
MG is caused by autoantibodies that target proteins at the neuromuscular junction, where nerve and muscle cells communicate to coordinate voluntary movements. For most patients, these antibodies target acetylcholine receptors, or AChRs.
MG symptoms include muscle weakness and fatigue, and certain factors, such as infections, stress, or medications, may trigger exacerbations, which refer to episodes of disease worsening. In some cases, the episodes may require patients to be admitted to intensive care.
Admitted to intensive care
To know more about the risk factors and prognosis of people with MG who require intensive care, researchers at the University of Helsinki in Finland retrospectively analyzed the medical records of 577 MG patients.
Overall, 167 MG patients were admitted to intensive care for any reason. From these, 35 were admitted due to an MG exacerbation, mainly an MG crisis (71.4%), which was defined as an MG exacerbation that required breathing support or nasogastric intubation, that is, placing a special tube that carries food and medicine to the stomach through the nose. Other reasons for intensive care admission included cardiovascular and respiratory diseases, infections, surgical, or traumatic issues.
There were also 180 MG patients who were admitted to the neurology hospital ward for MG exacerbations, and 171 who were followed on outpatient care.
The patients who needed intensive care were generally older at the time of their diagnosis than those admitted to the neurology ward or followed in outpatient care (60.5 vs. 53.4 vs. 48.3). The proportion of patients with late-onset MG was also higher in the intensive care group compared with the neurology ward or outpatient groups (77.1% vs. 58.3% vs. 51.5%). Patients requiring intensive care were also more likely to have a thymoma than those admitted to the neurology ward or on outpatient care (11.4% vs. 2.2% vs. 1.2%).
Risk factors include being female, having thymoma
Being female or having a thymoma were independent risk factors for admission to intensive care due to an MG exacerbation or MG crisis, further analysis showed. The risk of intensive care unit admission was twice as high among women patients, and almost five times higher in those with a tumor in the thymus gland, or thymoma.
The 35 patients admitted to intensive care for MG exacerbations or crisis had a mean age of 63.4 at the time of the first admission, with infections being the most common triggering event for disease exacerbation (42.9%). These patients were admitted to intensive care within a median of 5.3 months after their diagnosis, although about a fifth (22.9%) were admitted before they were diagnosed.
According to the researchers, “this highlights the importance of suspecting MG in unclear respiratory failure cases. Compared to asthma, an autoimmune respiratory disease affecting 10% of adults in Finland, we found that the need for intensive care for respiratory failure is more pronounced in MG,” the researchers wrote.
In general, longer stays in intensive care were associated with more severe disease, longer in-hospital stays, and higher mortality within six months following a stay in intensive care. The overall in-hospital mortality rate for patients with an MG crisis was 4% and was 4.8% among those who needed mechanical ventilation.
“In conclusion, our study shows an increased risk of intensive care for MG exacerbation in patients with [late-onset MG], several comorbidities, female sex or thymoma, occurring usually within [six] months from diagnosis,” the researchers wrote.
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