Patients with myasthenia gravis report 'unacceptable' disease burden in large study

Nearly half of individuals in a study about activities of daily living among more than 1,000 patients with myasthenia gravis reported disease symptoms associated with an “unsatisfactory” state, according to findings published in Neurology.

“The Genes and Environment in Myasthenia Gravis (GEMG) study was launched in order to provide improved information on causative factors and disease characteristics in a large nationwide cohort,” Malin Petersson, MD, a PhD student at Karolinska Institutet in Sweden, and colleagues wrote. “The main objective of the present study was to describe the basic and disease-specific characteristics of the GEMG study cohort in relation to symptom severity as reflected by the Myasthenia Gravis-Activities of Daily Living (MG-ADL scale).”

In a cross-sectional prevalent cohort study, Petersson and colleagues analyzed data from 1,077 Swedish patients with myasthenia gravis (mean age at inclusion, 64.3 years; 53% female; mean disease duration, 14.6 years). Researchers screened participants as part of the GEMG study between November 2018 and August 2019.

The participants submitted an “extensive and standardized” 106-item life environment questionnaire, including their MG-ADL scale score. Researchers used age to evaluate early onset MG (EOMG, <50 years), late onset MG (LOMG, 50 years) or thymoma-associated MG (TAMG). They compared disease-specific characteristics across subgroups, sex and different MG-ADL scores. The previously reported score of 2p in MG-ADL as a satisfactory state in MG served as the cut-off in the study.

Among the 1,077 patients (74% response rate), 505 (47%) were classified as EOMG, 520 (48%) as LOMG and 45 (4%) as TAMG. Fully complete MG-ADL scores (n = 1,035) ranged from 0 to 18p; 26% reported a score of 0p. Of the total patient population, almost half (47%) reported a score of 3p on the MG-ADL, which represented an unsatisfactory symptom state.

Researchers found that higher MG-ADL scores correlated with female sex (OR = 1.62), obesity (OR = 1.72) and diagnostic delay (OR = 1.69) and inversely correlated with high educational attainment (OR = 0.59). They reported no association between high scores and age at inclusion, disease subtype or disease duration.

Limitations of this study include potential selection biasas the researchers included fewer than half of all patients diagnosed with MG in Sweden, patient-reported data and the potential exclusion of prescribed treatments. The researchers noted that a study linking the GEMG database with the national registry of prescribed drugs is being planned to ascertain “more precise” information on this subject.

“In this nationwide study, comprising more than 40% of the prevalent MG population in Sweden, we observe that almost half of patients report current disease symptoms associated to an unsatisfactory symptom state, indicating the need for improved treatment options,” Petersson and colleagues wrote.

In a related editorial, Chloe Atkins, PhD, and Carolina Barnett, MD, PhD, of the University of Toronto, noted the “impressive coverage” of the survey response from Petersson and colleagues while also noting that such a high proportion of unacceptable disease burden “should give us pause.” They acknowledged that some level of bias could be present in the results, but that this bias should not prevent researchers from trying to improve outcomes among patients with MG.

“The Petersson et al. study is important in that it suggests that the successful management of MG patients’ symptoms may well demand more due consideration,” Atkins and Barnett wrote. “While neurologists have been able to reduce mortality from MG by generally improving muscle strength, we now know that up to half of [patients with MG] continue to live without the adequate vigor and stamina to properly enjoy life.”