Investigators found that women with early-onset myasthenia gravis display distinct clinical features in contrast with men with the same condition, who are more like patients with late-onset MG of both sexes.
Using the myasthenia gravis activities of daily (MG-ADL) score, investigators were able to describe the clinical characteristics for patients with myasthenia gravis (MG) in Sweden as well as highlight gaps within the treatment space, which was emphasized by almost half of the study population reporting an unsatisfactory symptom state.
The Genes and Environment in Myasthenia Gravis (GEMG) study, performed from November 2018 through August 2019, comprised of 1077 individuals with MG, roughly 42% of all patients with the disease in Sweden. Patients were invited to participate by responding to an extensive and standardized online or paper questionnaire regarding historic and present environmental and lifestyle exposures as well as disease-specific questions.
Senior author Susanna Brauner, MD, PhD, assistant professor of neurology, Karolinska Institutet, and colleagues classified patients into either early-onset MG (EOMG, <50 years at onset; n = 505 [47%]), late-onset MG (LOMG, ≥50 years; n = 520 [48%]), or thymoma-associated MG (TAMG; n = 45 [4%]). The EOMG was found to be dominated by female patients (76%), contrasting with the LOMG group (30%; P <.001).
Disease activity was assessed by the MG-ADL scale and scores ranged between 0 points and 18 points. A large proportion of patients reported 0 points (26%) and similar fractions of patients with no (0 points), mild (1-2 points), or moderate disease activity (3-5 points) or severe generalized disease (≥6 points) were observed between the subgroups.
Using a multivariate regression model, investigators found that female sex (OR, 1.62 [95% CI, 1.09-2.41; P adjusted = .017), obesity (OR, 1.72 [95% CI, 1.12-2.64]; P adjusted = .013) and diagnostic delay of at least 2 years (OR, 1.69 [95% CI, 1.14-2.48]; P adjusted = .008) significantly correlated with high rates of disease activity. Notably, an inverse correlation with severe generalized disease was observed for patients who obtained a university degree (OR, 0.59 [95% CI, 0.37-0.91]; P adjusted = .02).
MG-ADL scores of at least 3 points, or negative on estimated patient acceptable symptom state (ePASS), were reported by 47% of the cohort, indicating dissatisfaction with their current disease state. Patients who demonstrated these scores at study inclusion more often had general symptoms at onset compared to patients with MG-ADL 0-2 points (44% vs 37%; P = .019) and more reported ever having generalized symptoms (83% vs 73%; P <.001).
Only 37% of patients who were diagnosed within 2 years prior to study inclusion had MG-ADL 0-2 points, compared to 55% of those who were diagnosed earlier (P <.001). Notably, differences between the groups remained significant after adjusting for subgroup and age (OR, 2.17 [95% CI, 1.40-3.41]; P adjusted <.001). Brauner et al wrote, “taken together, our findings underscore a need to improve treatment algorithms and develop more effective disease-modulatory drugs."
At onset, patients with EOMG more often reported generalized symptoms (50%), whereas those in the LOMG group demonstrated more ocular symptoms (55%)(P <.001). Investigators observed a significantly earlier onset of symptoms for female patients with EOMG (mean, 27.6 years [standard deviation (SD), 9.4], than men with EOMG (33.4 [SD, 10.8]; P <.001). Additionally, significantly more women with EOMG reported generalized symptoms at onset (55% vs 37%, P <.001) or ever (92% vs 74%; P <.001).