Health-related quality of life measurement for Brazilian patients with Myasthenia gravis

Background : Myasthenia gravis significantly impacts patients' quality of life, yet utility data from Latin America remain scarce. This study assessed health-related quality of life and generated utility values for Brazilian patients with MG. Methods : In this cross-sectional study, 317 Brazilian patients with MG completed online questionnaires, including the EQ-5D-3 L and MG-ADL instruments. Multiple regression models were used to examine the relationships between symptom severity and utility values. Mapping algorithms were developed to convert MG-ADL scores to utility values. Results : The mean EQ-5D-3 L score was 0.55 (SD 0.16), representing a 35% reduction from Brazilian population norms. The most significant decreases in utility were associated with mobility limitations (-0.0768, p<0.001) and self-care difficulties (-0.0451, p<0.001). Each one-point increase in the MG-ADL score corresponded to a decrease in utility of 0.024 (p<0.001). The final prediction model explained 44.9% of the utility variance. Conclusions : This is the first Brazilian MG utility study to demonstrate substantial quality of life impairment and provide validated mapping tools for economic evaluation. The results enable more accurate health technology assessments and support evidence-based resource allocation in Latin American healthcare systems.