Concepts and Assessment of Fatigue in Myasthenia Gravis: A Scoping Review

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. 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. 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. 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. Fatigue is a burdensome symptom for people living with myasthenia gravis (MG) that can significantly affect daily activities. Patients can experience different types of fatigue. Patients may also mean different things when they talk about their fatigue, which makes it hard to measure. This is true in MG research too. This review aimed to summarise how fatigue in MG is described, and to identify the assessments used to measure fatigue in people with MG. We also evaluated the usefulness of these assessments for clinicians and patients using three criteria. These criteria were the ability of a scale to (1) identify patients with clinically relevant fatigue; (2) measure different levels of fatigue severity; and (3) detect meaningful changes in fatigue over time. We found 13 types of fatigue (“fatigue concepts”) described in MG research, with a lot of overlap in how they were defined. Our review also found 18 assessments used to measure fatigue in people with MG. Each assessment covered different fatigue concepts. No fatigue scale used in MG fulfilled all three criteria for usefulness. Only two of the assessments (Quality of Life in Neurological Disorders Short Form Fatigue and MG Symptoms Patient-Reported Outcome Physical Fatigue) could determine a “meaningful change” in fatigue for people with MG. Our review highlights the variability in how fatigue is assessed in MG. Clearer definitions of fatigue concepts and further investigation of fatigue assessment scales could help people with MG-related fatigue feel understood, and be assessed and treated appropriately.