Clinical profile and quality of life in late-onset and very-late-onset myasthenia gravis: a cross-sectional study.

Background: The incidence of late-onset and very-late-onset myasthenia gravis (MG) has increased worldwide, but national data in Brazil remain scarce. Characterizing the clinical profile and quality of life (QoL) of these patients is essential to improve care strategies. Objective: To describe the clinical profile and assess QoL of patients with late- and very-late-onset MG followed at a Brazilian tertiary hospital, comparing them with early-onset MG patients. Methods: Cross-sectional observational study including adult MG patients followed at a tertiary university hospital. Demographic, clinical, serological, neurophysiological, and radiological data were collected. Disease severity was assessed using the Myasthenia Gravis Composite (MGC) and Quantitative Myasthenia Gravis (QMG) scales. Furthermore, QoL was assessed using the 15-item Myasthenia Gravis QoL questionnaire (MG-QOL15). Correlation analyses were performed between MG-QOL15, MGC, and QMG scores. Results: In total, 28 MG patients were included: 13 early-onset, 7 late-onset, and 8 very-late-onset. Male predominance, shorter disease duration, and absence of thymectomy were more frequent in the late and very-late-onset groups. These subgroups also showed better symptom control and perceived QoL, particularly the very-late-onset group. The MG-QOL15 scores showed a moderate correlation with MGC and a weaker correlation with QMG. Conclusion: Late-onset and very-late-onset MG patients showed satisfactory QoL and clinical profiles, consistent with international data. These correlations reinforce the complementary role of patient-reported outcomes alongside objective clinical scales. Further studies with larger cohorts and longitudinal follow-up are needed.