The Fatigue Assessment Scale as a Simple and Reliable Tool in Systemic Lupus Erythematosus

A Cross-Sectional Study

Alice Horisberger; Delphine Courvoisier; Camillo Ribi

Disclosures

Arthritis Res Ther. 2019;21(80) 

In This Article

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a wide spectrum of clinical and biological manifestations. The multiple dysfunctions in the innate and adaptive immune system that ultimately lead to autoimmunity and inflammation are thought to be triggered by various environmental factors in genetically susceptible individuals.[1] The vast majority of SLE patients complain about fatigue[2,3] and report it as one of the most debilitating disease features.[4,5] Whether fatigue reflects SLE disease activity is still a matter of debate.[6] Lupus fatigue has important repercussions on daily activities and is associated with poor quality of life (QoL).[7] By using a qualitative interview tool, Sterling et al. highlighted its negative impact on emotional, cognitive, professional, and social status.[8] Given its major role on patient's morbidity, fatigue is an essential aspect to consider in SLE management. Yet, fatigue remains poorly understood by both health care providers and the patient's entourage.[9]

Multiple instruments for assessing fatigue and various definitions are available, without one standing out for its simplicity and reliability. Thus, fatigue is difficult to evaluate in daily practice and to standardize across studies for research purposes. The Fatigue Assessment Scale (FAS) is a simple 10-item self-reported questionnaire designed by Michielson et al. to assess fatigue in the general population and validated subsequently in the sarcoidosis setting.[10,11] The FAS is derived from a pool of 40 items selected in four previous valid questionnaires: the Fatigue Scale, the Checklist Individual Strength, the Emotional Exhaustion subscale of the Dutch version of the Maslach Burnout Inventory, and the Energy and Fatigue subscale of the World Health Organization Quality of Life assessment instrument. The face validity was studied through a semantical analysis in order to guide the selection of items. The FAS is reportedly a unidimensional scale measuring fatigue independently from depression.[12] It has proven to be a reliable and valid tool as well as sensitive to change in sarcoidosis patients.[13] Owing to its good psychometric properties in this specific disease, this instrument was then used in a placebo-controlled randomized clinical trial evaluating the effect of N-acetylcysteine on fatigue in SLE.[14,15] However, the reliability and validity of FAS in SLE patients have yet to be demonstrated. In this study, the primary objective was to study the construct, the convergent validity, and test-retest correlation of the FAS in SLE patients. Secondary objectives were to compare the fatigue score between SLE patients, non-SLE patients, and healthy volunteers; to measure perceived fatigue in SLE patients with active and inactive disease; and to determine whether other factors contribute to fatigue.

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