Fatigue, physical activity and associated factors in 779 patients with myasthenia gravis

Linda Kahr Andersen,Mette Aadahl,John Vissing

doi:10.1016/j.nmd.2021.05.007

Abstract

The objective of the study was to examine the association between fatigue (measured by the Multidimensional Fatigue Inventory; MFI-20) and physical activity (measured by the Saltin-Grimby Physical Activity Level Scale; SGPALS) in a large cohort of patients (≥18 years) with myasthenia gravis (MG) including relevant disease - and lifestyle-related factors. A total of 1463 persons, registered at the Danish National Registry of Patients with a MG diagnosis, according to the International Classification of Diseases, received a web-based survey. A total of 779 patients (53% women, mean [SD] age 60.8 [15.5]) responded. The remaining persons were either non-responders (n = 390) or could not confirm the MG diagnosis (n = 294). The most prominent MFI-20 fatigue domains were general fatigue (median [inter-quartile ranges, IQR], 13 [10–16]) and physical fatigue (median [IQR], 13 [9–15]), and 386 (53%) patients reported low levels of physical activity. All fatigue domains were associated with physical activity (p<.01). Higher level of physical activity was associated with lower levels of fatigue. Important factors for the association were myasthenia gravis disease severity (measured by the Myasthenia Gravis Activities of Daily Living profile), body mass index, insomnia (measured by the Insomnia Severity Index) job-status, comorbidity, and cohabitation.

Highlights

Myasthenia gravis (MG) is a chronic, autoimmune disease with fluctuating strength of voluntary muscles and distinct muscular fatigue
Many patients with MG in our clinic complain about another type of fatigue; a severe, overwhelming and constant fatigue that does not disappear at rest and is perceived different from the well-known and well-described muscular fatigue
Patients with a median score ≥13 (n = 358, 50%) compared to patients with a score

Summary

Introduction

Myasthenia gravis (MG) is a chronic, autoimmune disease with fluctuating strength of voluntary muscles and distinct muscular fatigue. In one attempt of defining fatigue in neurological diseases, fatigue was categorized into peripheral and central fatigue [1]. Central fatigue was defined as a subjective sense of fatigue including both cognitive and mental fatigue [1]. When using this definition of central fatigue, previous studies in MG have reported a prevalence of patient-reported central fatigue between 42 and 82% [2]. Central fatigue has been related to MG severity, autonomic disturbances, depressive state, female sex, and sleep disturbances [3,4,5,6,7], and has a substantial impact on activities of daily living and quality of life [3,4]. Continuous variables were presented by means and standard deviation (SD).

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Conclusion