Multidimensional daily diary of fatigue–fibromyalgia–17 items (MDF-fibro-17). part 1: development and content validity

Abstract

BackgroundFibromyalgia (FM), a disorder characterized by chronic widespread pain and tenderness, affects greater than five million individuals in the United States alone. Patients experience multiple symptoms in addition to pain, and among them, fatigue is one of the most bothersome and disabling. There is a growing body of literature suggesting that fatigue is a multidimensional concept. Currently, to our knowledge, no multidimensional Patient Reported Outcome (PRO) measure of FM-related fatigue meets Food and Drug Administration (FDA) requirements to support a product label claim. Therefore, the objective of this research was to evaluate qualitative and quantitative data previously gathered to inform the development of a comprehensive, multidimensional, PRO measure to assess FM-related fatigue in FM clinical trials.MethodsExisting qualitative and quantitative data from three previously conducted studies in patients with FM were reviewed to inform the initial development of a multidimensional PRO measure of FM-related fatigue: 1) a concept elicitation study involving in-depth, open-ended interviews with patients with FM in the United States (US) (N = 20), Germany (N = 10), and France (N = 10); 2) a cognitive debriefing and pilot study of a preliminary pool of 23 items (N = 20 US patients with FM); and 3) a methodology study that explored initial psychometrics of the item pool (N = 145 US patients with FM).ResultsFive domains were identified that intend to capture the broad experience of FM-related fatigue reported in the qualitative research: the Global Fatigue Experience, Cognitive Fatigue, Physical Fatigue, Motivation, and Impact on Function. Seventeen of the original pool of 23 items were selected to best capture these five dimensions. These 17 items formed the basis of a newly developed multidimensional PRO measure to assess FM-related fatigue in clinical trials: the Multidimensional Daily Diary of Fatigue-Fibromyalgia-17 (MDF-Fibro-17).ConclusionQualitative analysis, and preliminary quantitative item level data, confirmed that FM-related fatigue is multidimensional and provided strong support for the content validity of the MDF-Fibro-17. The next stage was to quantitatively evaluate the measure to confirm the factor structure, psychometric properties, sensitivity to change, and meaningful change. This has been conducted and is being reported separately.

The Multidimensional Daily Diary of Fatigue-Fibromyalgia-17 Items (MDF-Fibro-17): Evidence from Validity, Reliability and Transcultural Invariance between Portugal and Brazil

“…Additionally, the focus group of the scale were individuals with chronic fatigue not related to any specific medical condition (e.g., FM). Thus, due to the lack of valid instruments for measuring fatigue in patients with FM, Morris and colleagues [10,12] developed the Multidimensional Daily Diary of Fatigue-Fibromyalgia-17 (MDF-fibro-17). The MDF-fibro-17 was created to measure and evaluate the different components of FM-related fatigue, so that it could be possible to understand the general and specific complexity of fatigue in patients with FM [12].…”

“…The questionnaire comprises 17 items that measure five dimensions of fatigue in patients with FM, namely: (i) Global fatigue experience; (ii) Cognitive fatigue; (iii) Physical fatigue; (iv) Motivation; and (v) Impact on function. This subdivision is due to the recognition and acceptance of fatigue as a multidimensional factor and to the need for investigation and treatment for each specific dimension of fatigue [10].…”

“…Looking deeper at each dimension, global fatigue experience captures certain general points of fatigue which are not suitable for other, more specific domains, as patients with FM use a variety of terms to describe their symptoms of fatigue. This dimension is paramount, since several global terms have been used involving important and comprehensive elements to capture the experience of fatigue in a global manner [10,13]. FM patients also report that their fatigue affects them both physically and mentally [10,14].…”

“…This dimension is paramount, since several global terms have been used involving important and comprehensive elements to capture the experience of fatigue in a global manner [10,13]. FM patients also report that their fatigue affects them both physically and mentally [10,14]. With this in mind, there are cognitive limitations described by patients with FM, such as mental tiredness, which end up impacting the concentration to perform specific tasks, to think clearly or to remember something.…”

“…Specifically, patients with FM report that their fatigue is characterized by excessive physical and cognitive tiredness and is not usually eased after hours of sleep or rest, which ends up making it the biggest obstacle for them to overcome physical inactivity and to perform daily tasks [6][7][8]. Thus, the assessment of fatigue helps patients grade the severity of the symptoms of FM, and it is used as a reference when they are asked about their well-being and quality of life [6,9,10].…”