Table 1.

Unidimensional and multidimensional questionnaires used to assess fatigue in COVID-19.

Instrument	Description	Findings in COVID-19
Unidimensional
Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT)	It has 13 items assessing the perception of fatigue related to the last seven days and the answers are given on a Likert scale from 0 to 4 points (Cella et al. 2002).	The mean total score for fatigue was 16.8 (13.2) points among the 1036 subjects at the seventh month after hospitalization for COVID-19(Evans et al., 2021).
Brief Fatigue Inventory	It has an item about fatigue of the last week (yes or no). There are three rating items with scores from 0 to 10 for fatigue severity at "now", "usual" and "worst" times. And six items that assess the impact of fatigue over the past 24 h(Y. W. Chen, Coxson, and Reid 2016).	Fatigue present up to 163 days after COVID-19, assessed in 315 (93.2%) of 338 patients hospitalized for COVID-19, of whom 150 (47.6%) had moderate fatigue (4–6 points) (Stallmach et al., 2022).
Visual Analog Scale – Fatigue	Visual analog scale that assesses the severity of fatigue in a numerical measure from 0 to 10(Tseng, Gajewski, and Kluding 2010).	The mean score for physical fatigue was 8 points and 7 for mental fatigue in 150 subjects hospitalized for COVID-19(Tuzun et al., 2021).
Fatigue Severity Scale	It assesses the severity of fatigue on nine items referring to perceived fatigue over the past two weeks. Each item is scored from 1 (strongly disagree) to 7 points (strongly agree)(Krupp and Pollina 1996).	Of the 124 subjects evaluated, 71(57%) had relevant fatigue at hospital discharge (≥ 4 points) post-COVID-19(Leite et al., 2022).
Fatigue Impact Scale	It assesses the impact of fatigue on subjects' functional limitation in the last month. Recently adapted (modified version) to be responsive to daily use with eight items ranging from 0 to 4 points(Fisk and Doble 2002).	NE
Modified BORG Scale	Assesses the perception of fatigue on a scale of 0–10 points(Borg et al. 2010).	In the walk test, perceived fatigue was on average 1.9 (1.8) points in a sample of 186 subjects who underwent hospitalization for COVID-19(Cortés-Telles et al., 2021).
Multidimensional
Checklist Individual Strength	It consists of a 20-item instrument with four domains (subjective fatigue, motivation, activity and concentration), referring to the last two weeks (Vercoulen et al. 1994).	138 (56.1%) of 246 patients who had been in an Intensive Care Unit had abnormal fatigue (27 points or more) up to one year after (Heesakkers et al., 2022).
Piper Fatigue Scale	It assesses behavioral, affective, sensory, mood-related, and cognitive aspects. The revised version has 22 items with Likert-type responses ranging from 0 to 10(Reeve et al. 2012).	NE
Multidimensional Fatigue Inventory	A 20-item instrument for assessing general fatigue, physical fatigue, mental fatigue, reduced activity, and reduced motivation. The score is given for each domain and ranges from 4 to 20 points(Smets et al., 1995).	Patients who were hospitalized for COVID-19 had persistent fatigue with high scores in the domain of reduced motivation and mental fatigue(Morin et al., 2021).
Chalder Fatigue Questionnaire	11-item instrument that assesses the domains mental fatigue and physical fatigue and each item is scored from 0 to 3 points (Chalder et al., 1993).	Fatigue was present in 120 (80%) of 150 subjects (Tuzun et al., 2021). The post-viral fatigue burden in post-COVID-19 patients was high with a mean total score of 15.1 (5.0) points (out of 33)(Stavem et al., 2021).
Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M)	Assesses the impact of fatigue on the activities of daily living in a domain ranging from 0 to 100 points(Lareau, Meek, and Roos 1998).	Fatigue had a positive association with functional status ( r = 0.491, p = 0.045) among participants with COVID-19(Carter et al., 2022).

Legend: NE (NOT EVALUATED).