Worse MG muscle weakness linked to more daily activity impairment
Real-world study finds worse impairment for patients with severe weakness
Among people with myasthenia gravis (MG), the degree of daily activity impairment is greater for those with more severe and more widespread muscle weakness, according to real-world data from a survey of physicians in the U.S. and Europe.
However, the study — which involved clinicians treating more than 1,200 MG patients — also showed symptom variability among individuals with the same degree of muscle weakness.
“Results of this multinational, real-world survey … revealed that [activities of daily living] impairment broadly increased with increasing [Myasthenia Gravis Foundation of America] classification, i.e. the site and degree of muscle weakness,” the researchers wrote, noting that the findings showed “the requirement for assistance with oral hygiene or arising from a chair” for many patients.
Titled “Clinical characteristics and impairment of activities of daily living among patients with myasthenia gravis with differing degrees of muscle weakness: a real-world study of patients in the US and five European countries,” the study was published in the journal BMC Neurology.
Over 200 doctors surveyed on impact of muscle weakness on patients
In MG, the immune system produces self-reactive antibodies that mistakenly attack proteins involved in the communication between nerve and muscle cells, leading to symptoms like muscle weakness.
Now, researchers at Janssen and their colleagues analyzed data from a large real-world survey to assess how varying degrees of muscle weakness — assessed using the five-part classification system from the Myasthenia Gravis Foundation of America (MGFA) — affect the daily activity of patients.
The survey, conducted as part of the Adelphi Real World MG Disease Specific Programme, was completed by 222 physicians. These healthcare providers were following a total of 1,232 MG patients in the U.S. (37%), France (10.4%), Germany (8.3%), Italy (12.3%), Spain (19.8%) and the U.K. (12.3%). The patients had a mean age of 54.2.
Most physicians were neurologists (72.4%), followed by general practitioners (25.5%) and geriatricians (2.1%).
According to the MGFA classification system, more than a quarter of patients — 367 or 29.8% — were classified as class 1 or having ocular MG, meaning that muscle weakness was restricted to muscles that control the movement of the eyes and eyelids. A total of 579 patients (47%) met the criteria for class 2, indicating mild generalized MG.
More severe symptoms, defined as class 3/4, were seen in 286 individuals (23.2%). Patients in the most severe stages of the disease and in need of intubation, who are classified as class 5, were excluded from the analysis.
According to the researchers, participants in class 2 had been diagnosed closer to the survey date than patients in the other groups. Differences also were found in the Charlson Comorbidity Index, an indication of mortality risk and the severity of comorbidities, or coexisting conditions, which was higher — meaning worse — in class 3/4.
Greatest effects on daily activity seen for those in MGFA class 3/4
Impairments in activities of daily living were scored from 0 to 22, with higher scores indicating greater impairments.
Overall, patients with less severe symptoms (class 1) had significantly fewer impairments to their daily life activities compared with classes 2 to 4, after adjusting for sex and coexisting disorders.
Specifically, those in class 1 had a mean daily impairment activity score of 1.9 versus 3.5 for those in class 2, and 6 for those in class 3/4.
[These findings] highlight the impact of poor disease control on a patient’s lived experience, across every MGFA class.
Within each MGFA class, however, symptom severity varied. For example, bulbar symptoms — those generally involving the facial muscles, and including impaired speech, swallowing, and chewing — and shortness of breath mostly of mild to moderate severity were seen among some patients in class 1 and class 2. But in participants in classes 3 and 4, bulbar symptoms and shortness of breath were only mild in severity.
Also, patients in all classes were at risk of experiencing myasthenic crisis, a sudden worsening of symptoms, or hospitalization, as well as developing anxiety and depression. A total of 7.4% of participants in class 1, 12.1% in class 2, and 40.6% in class 3/4 were not in remission.
“Taken together, these results highlight the variability between patients assessed as having the same degree of muscle weakness, in terms of the symptoms experienced, their disease burden, and the impact on their [activities of daily living],” the scientists wrote.
Further, the team added, these findings “also highlight the impact of poor disease control on a patient’s lived experience, across every MGFA class.”
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