Fatigue is a major problem in a wide range of (chronic) diseases including interstitial lung disease (ILD) and sarcoidosis. Fatigue is the most frequently described and globally recognized as a disabling symptom. The reported prevalence varies from 60% to 90% of sarcoidosis patients, and up to 25% of fatigued sarcoidosis patients report extreme fatigue. Also, patient with idiopathic pulmonary fibrosis (IPF) reported to suffer from substantial fatigue.
Fatigue is defined as “an experience of tiredness, dislike of present activity, and unwillingness to continue”, or as a “disinclination to continue performing the task at hand and a progressive withdrawal of attention” from environmental demands. As a gradual and cumulative process, fatigue reflects vigilance decrement and decreased capacity to perform, along with subjective states that are associated with this decreased performance. It is a general psychophysiological phenomenon that diminishes the ability of the individual to perform a particular task by altering alertness and vigilance, together with the motivational and subjective states that occur during this transition. Consequently, there is reduced competence and willingness to develop or maintain goal directed behaviour aimed at adequate performance.
Several studies have reported that neither lung function tests nor chest radiographs correlate with nonspecific health complaints, including fatigue or QoL. Fatigue is often troubling to physicians to deal with because it does not relate directly to a physiologic abnormality, is difficult to quantify and hence to monitor, and is challenging to treat.
The Fatigue Assessment Scale (FAS) is now available in over 25 languages. It is a quick and easy tool for patients to complete without being time-consuming. Additionally, it serves as a valuable resource for physicians and other healthcare professionals in monitoring patients alongside standard functional tests, such as lung function assessments. The FAS has been validated as a reliable questionnaire for assessing fatigue in patients with ILD, as well as in many other chronic conditions.
The FAS is a 10-item questionnaire designed to assess general fatigue. Five questions measure physical fatigue, while five others (questions 3 and 6–9) assess mental fatigue.
An answer must be provided for every question, even if the respondent has no current complaints. Scores for questions 4 and 10 should be reversed (1=5, 2=4, 3=3, 4=2, 5=1). The total FAS score is then calculated by summing the scores of all questions, including the recoded values for questions 4 and 10. The total score ranges from 10 to 50, with a score below 22 indicating no fatigue and a score of 22 or higher indicating fatigue. All online versions of the FAS automatically calculate the total, mental, and physical fatigue scores.
Summary:
- FAS score 10–21: No fatigue (normal)
- FAS score 22–50: Substantial fatigue
- Fatigue: Score 22–34
- Extreme fatigue: Score ≥ 35
The Minimal Clinically Important Difference (MCID) is defined as a change of at least 4 points or a 10% change from the baseline value.
References
Drent M, Lower EE, De Vries J. Sarcoidosis-associated fatigue. Eur Respir J 2012; 40: 255–263. http://www.ncbi.nlm.nih.gov/pubmed/22441750
Kleijn WPE, De Vries J, Wijnen PAHM, Drent M. Minimal (clinically) important differences for the Fatigue Assessment Scale in sarcoidosis. Respir Med 2011; 105: 1388-95. http://www.ncbi.nlm.nih.gov/pubmed/21700440
De Vries, Michielsen H, Van Heck GL, Drent M. Measuring fatigue in sarcoidosis: the Fatigue Assessment Scale (FAS). Br J Health Psychol 2004; 9: 279-91. http://www.ncbi.nlm.nih.gov/pubmed/15296678
Hendriks C, Drent M, Elfferich M, De Vries J. The Fatigue Assessment Scale (FAS): quality and availability in sarcoidosis and other diseases. Curr Opin Pulm Med 2018; 24 (5): 495-503. https://pubmed.ncbi.nlm.nih.gov/29889115