Myasthenia gravis affects quality of life, even when symptoms are mild
Findings: Lower disease activity patients should be included in clinical trials
An analysis of the Swedish MG registry suggests that adults with myasthenia gravis (MG) have an impaired quality of life, even when they show low disease activity.
Muscle weakness affecting the limbs and breathing primarily drove a diminished quality of life. These findings indicate “an unmet medical need that warrants improved treatment and care,” the study’s researchers wrote. The findings were detailed in the study, “Impact of disease activity on quality of life and EQ-5D-3L score in myasthenia gravis: results from the Swedish MG registry,” in the Journal of Neurology.
Muscle weakness and fatigue are the hallmark symptoms of MG, an autoimmune disorder wherein self-reactive antibodies disrupt the communication between nerve and muscle cells. These symptoms tend to worsen with repetitive activity and ease with rest.
For many, the muscles of the eyes and eyelids are affected first, and when these are the only ones affected, it’s called ocular MG. However, most will eventually develop generalized MG (gMG), a more severe form with widespread muscle weakness that can affect breathing, swallowing, and walking.
The EuroQol 5-Dimension with three levels (EQ-5D-3L) is a patient-reported assessment of quality of life based on the impact on five areas of health — mobility, self-care, usual activities, pain and discomfort, and anxiety and depression. Scores range from 0 (worst) to 1 (best).
Worsening daily living scores and declining quality of life
The researchers used data from the Swedish MG registry to examine EQ-5D-3L scores in 150 Swedish adults with MG and the relationship with disease activity. The study was sponsored by UCB, maker of Rystiggo (rozanolixizumab-noli) and Zilbrysq (zilucoplan), two therapies approved for generalized MG.
On all five EQ-5D-3L dimensions, the proportion of patients reporting a moderate to severe impact was significantly higher than that of a Swedish reference population. The dimensions showing the greater impact were usual activities (44% vs. 8%), followed by self-care (9.3% vs. 1.9%).
A worse mean EQ-5D-3L score strongly correlated with an overall increase in disease activity, as indicated by the MG Activities of Daily Living (MG-ADL), which assesses how symptoms affect daily life. But the researchers observed lower EQ-5D-3L scores even in the adults with low to moderate disease activity, “which is concerning and underscores the need for more active treatment interventions in a larger proportion of MG patients.”
The scores were affected by involvement in all muscle groups assessed. Muscles in the limbs and those involved in breathing had the most significant impact, followed by those in the eyes, and in the face, and neck, called the bulbar muscles.
A worse mean EQ-5D-3L score also correlated with higher disease activity in the physician-evaluated Quantitative MG (QMG) assessment, and with lower quality of life, as reported on the MG-QoL-15 scale.
To investigate changes in activities of daily living (ADL) in relation to EQ-5D and MG-QoL-15 scores over time, the researchers turned to the Phase 3 RINOMAX (NCT02950155) trial, which tested rituximab as an add-on treatment to standard of care in 47 new-onset gMG patients, all of whose MG-ADL and EQ-5D-3L scores were recorded several times over nearly a year. During the follow-up, worsening ADL scores significantly correlated with declining quality of life in both tests.
Low EQ-5D scores were primarily driven by worsening respiratory and limb symptoms, along with those affecting the eyes. Changes in MG-QoL-15 scores were mainly affected by respiratory and limb symptoms, and, to a lesser extent, to ocular and bulbar symptoms.
“We find a significant impact on the EQ-5D score compared to the general population, already at low-moderate disease activity,” the researchers wrote. “Furthermore, there was a significantly larger impact of respiratory and limb symptoms on [quality of life] measures compared to bulbar and ocular symptoms. Our findings indicate an unmet medical need at low-to-moderate disease activity, in turn raising the question if also patients with milder disease activity scores should be included in clinical trials to develop more effective treatment algorithms.”
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