Humanistic burden and medical care patterns of real-world patients with myasthenia gravis in Japan

Mami Kasahara-Kiritani^1*Yosuke Saga²Sayuri Watanabe³Thomas Webb⁴Keira Herr⁴DaeYoung Yu⁵Ciara Ringland⁶Shiva Lauretta Birija⁶Joe Conyers⁶Gregor Gibson⁶Niall Hatchell⁶Nan Li¹

• ¹Integrated Market Access Division, Johnson & Johnson, Tokyo, Japan
• ²Medical Affairs Division, Johnson & Johnson, Tokyo, Japan
• ³R&D Global development, Johnson & Johnson, Tokyo, Japan
• ⁴Johnson & Johnson, Singapore, Singapore
• ⁵Johnson & Johnson, Seoul, Republic of Korea
• ⁶Adelphi Real World, Bollington, United Kingdom

Introduction: Myasthenia gravis (MG) is a rare autoimmune disease characterized by skeletal muscle weakness. As limited real-world data are available in Japan, we aimed to describe the humanistic burden of disease (primary aim), mainly with regards to health-related quality of life (HRQoL), and treatment patterns (secondary aim) in patients with generalized MG (gMG). Methods: Data were drawn from the Adelphi Real World MG Disease Specific Programme™, a cross-sectional survey of neurologists and their patients in Japan from August 2023 and January 2024. Analyses were descriptive. Results: Overall, 40 neurologists reported data for 128 patients, where 29 patients had self-reported data. Mean (standard deviation) patient age was 57.9 (16.0) years and 53.9% were female. At data collection, 98.4% of patients were receiving maintenance therapy (including novel treatments). Nonsteroidal immunosuppressant therapies were used at first-line of therapy in 54.5% of cases (n=67/123). Oral systemic steroids were most used (78.0% of patients at first-line [n=96/123], 77.9% at second-line [n=53/68], and 75.0% at third-line [n=15/20]). The median (IQR) duration from symptom onset to diagnosis was 2.0 (0.94.3) months. Of 28 patients with EQ-5D-5L data, 46.4% reported difficulties with usual activities, 42.9% with mobility, 21.4% with self-care, 53.6% with pain/discomfort, and 39.3% with anxiety/depression. Conclusion: Most patients in this Japanese cohort with gMG received maintenance therapy and the time from symptom onset to diagnosis was relatively short. However, impaired HRQoL remained.