Concepts and assessment of fatigue in myasthenia gravis: a scoping review

Introduction: Fatigue is a burdensome symptom for many patients with myasthenia gravis (MG) and severely reduces quality of life. Fatigue in MG is described using multiple, partially overlapping concepts, or domains, that are not uniformly defined. The aims of this scoping review were to identify and summarise fatigue concepts related to MG, to review fatigue assessment scales and to evaluate their clinical interpretability, including fatigue caseness, fatigue severity, and clinically meaningful change thresholds.

Methods: Searches were conducted to identify clinical and observational studies published between 1 January 1990 and 28 February 2025, on PubMed, Embase, ClinicalTrials.gov, EudraCT and Cochrane Library, which presented original research in MG and used a quantitative measurement to assess fatigue. Following identification of fatigue concepts and assessment scales, a targeted secondary search was performed to ascertain clinically meaningful change thresholds for each scale.

Results: Seventy-six studies were included. Thirteen fatigue concepts including mental, physical and general fatigue were identified and summarised, with several concepts overlapping. Eighteen fatigue scales used in MG research were identified. Only two scales, Quality of Life in Neurological Disorders Short Form Fatigue and MG Symptoms Patient-Reported Outcome Physical Fatigue, had change thresholds validated in MG.

Conclusion: This review highlights heterogeneity in fatigue concepts and assessment approaches used in MG. No single fatigue scale fulfils the key clinical requirements (assessment of caseness, fatigue severity, and presence of a validated clinically meaningful change threshold). Clearer conceptual definitions and further validation of fatigue scales in MG may improve clinical interpretability.