fatigue scale – American ME and CFS Society

The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength

Abstract:

OBJECTIVE: The Checklist Individual Strength (CIS) measures four dimensions of fatigue: Fatigue severity, concentration problems, reduced motivation and activity. On the fatigue severity subscale, a cut-off score of 35 is used. This study 1) investigated the psychometric qualities of the CIS; 2) validated the cut-off score for severe fatigue and 3) provided norms.

METHODS: Representatives of the Dutch general population (n=2288) completed the CIS. The factor structure was investigated using an exploratory factor analysis. Internal consistency and test-retest reliability were determined. Concurrent validity was assessed in two additional samples by correlating the CIS with other fatigue scales (Chalder Fatigue Questionnaire, MOS Short form-36 Vitality subscale, EORTC QLQ-C30 fatigue subscale). To validate the fatigue severity cut-off score, a Receiver Operating Characteristics analysis was performed with patients referred to a chronic fatigue treatment centre (n=5243) and a healthy group (n=1906). Norm scores for CIS subscales were calculated for the general population, patients with chronic fatigue syndrome (CFS; n=1407) and eight groups with other medical conditions (n=1411).

RESULTS: The original four-factor structure of the CIS was replicated. Internal consistency (α=0.84-0.95) and test-retest reliability (r=0.74-0.86) of the subscales were high. Correlations with other fatigue scales were moderate to high. The 35 points cut-off score for severe fatigue is appropriate, but, given the 17% false positive rate, should be adjusted to 40 for research in CFS.

CONCLUSION: The CIS is a valid and reliable tool for the assessment of fatigue, with a validated cut-off score for severe fatigue that can be used in clinical practice.

Source: Worm-Smeitink M, Gielissen M, Bloot L, van Laarhoven HWM, van Engelen BGM, van Riel P, Bleijenberg G, Nikolaus S, Knoop H. The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength. J Psychosom Res. 2017 Jul;98:40-46. doi: 10.1016/j.jpsychores.2017.05.007. Epub 2017 May 8. https://www.ncbi.nlm.nih.gov/pubmed/28554371

Validation of the Flinders Fatigue Scale as a measure of daytime fatigue

Abstract:

STUDY OBJECTIVES: To clinically validate the Flinders Fatigue Scale (FFS) as a brief measure of daytime fatigue, and to derive cut-off scores to classify fatigue severity.

METHOD: The FFS was administered to 439 adult volunteers from the general population, 292 adults with insomnia, 132 adults with Obstructive Sleep Apnoea (OSA) and 66 adults with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME), together with the Fatigue Severity Scale (FSS) and the Epworth Sleepiness Scale (ESS).

RESULTS: A factor analysis revealed a single factor solution for the seven-item scale (67% of total variance), although a better fit was obtained for a modified six-item version (75% of total variance). Group FFS scores varied in accordance with theorised fatigue levels, with CFS/ME and insomnia samples reporting significantly higher fatigue than OSA and volunteer samples. Good convergent validity was established with the FSS for volunteer (r = 0.67) and CFS/ME samples (r = 0.61). Excellent discriminant validity with the ESS was observed for the insomnia (r = -0.08) and CFS/ME groups (r = 0.03), while a small-to-moderate correlation was found within the volunteer sample (r = 0.29). Cut-off scores were identified to categorise borderline (13-15), moderate (16-20) and severe (≥21) fatigue.

CONCLUSIONS: The FFS is a reliable and valid instrument to quantify subjective daytime fatigue. Sensitivity and specificity analyses indicate scores that best discriminate insomniacs and CFS/ME populations from a non-clinical population. However, it is proposed that the data can also be used to indicate the severity of fatigue by reference to these first two groups.

Source: Cameron K, Williamson P, Short MA, Gradisar M. Validation of the Flinders Fatigue Scale as a measure of daytime fatigue. Sleep Med. 2017 Feb;30:105-112. doi: 10.1016/j.sleep.2016.11.016. Epub 2016 Dec 3. https://www.ncbi.nlm.nih.gov/pubmed/28215232

Fatigue Scales and Chronic Fatigue Syndrome: Issues of Sensitivity and Specificity

Abstract:

Few studies have explored issues of sensitivity and specificity for using the fatigue construct to identify patients meeting chronic fatigue syndrome (CFS) criteria. In this article, we examine the sensitivity and specificity of several fatigue scales that have attempted to define severe fatigue within CFS. Using Receiver Operating Characteristic (ROC) curve analysis, we found most scales and sub-scales had either significant specificity and/or sensitivity problems.

However, the post-exertional subscale of the ME/CFS Fatigue Types Questionnaire (Jason, Jessen, et al., 2009) was the most promising in terms of specificity and sensitivity. Among the more traditional fatigue scales, Krupp, LaRocca, Muir-Nash, and Steinberg’s (1989) Fatigue Severity Scale had the best ability to differentiate CFS from healthy controls. Selecting questions, scales and cut off points to measure fatigue must be done with extreme care in order to successfully identify CFS cases.

Source: Jason LA, Evans M, Brown M, Porter N, Brown A, Hunnell J, Anderson V, Lerch A. Fatigue Scales and Chronic Fatigue Syndrome: Issues of Sensitivity and Specificity. Disabil Stud Q. 2011 Winter;31(1). Pii: 1375. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181109/ (Full article)

Further validation of the Multidimensional Fatigue Inventory in a US adult population sample

Abstract:

BACKGROUND: The Multidimensional Fatigue Inventory (MFI-20) was developed in 1995. Since then, it has been widely used in cancer research and cancer-related illnesses but has never been validated in fatiguing illnesses or in a large US population-selected sample. In this study, we sought to examine the reliability and validity of the MFI-20 in the population of the state of Georgia, USA. Further, we assessed whether the MFI-20 could serve as a complementary diagnostic tool in chronically fatigued and unwell populations.

METHODS: The data derive from a cross-sectional population-based study investigating the prevalence of chronic fatigue syndrome (CFS) in Georgia. The study sample was comprised of three diagnostic groups: CFS-like (292), chronically unwell (269), and well (222). Participants completed the MFI-20 along with several other measures of psychosocial functioning, including the Medical Outcomes Survey Short Form-36 (SF-36), the Zung Self-Rating Depression Scale (SDS), and the Spielberger State-Trait Anxiety Inventory (STAI). We assessed the five MFI-20 subscales using several criteria: inter-item correlations, corrected item-total correlations, internal consistency reliability (Cronbach’s alpha coefficients), construct validity, discriminant (known-group) validity, floor/ceiling effects, and convergent validity through correlations with the SF-36, SDS, and STAI instruments.

RESULTS: Averaged inter-item correlations ranged from 0.38 to 0.61, indicating no item redundancy. Corrected item-total correlations for all MFI-20 subscales were greater than 0.30, and Cronbach’s alpha coefficients achieved an acceptable level of 0.70. No significant floor/ceiling effect was observed. Factor analysis demonstrated factorial complexity. The MFI-20 also distinguished clearly between three diagnostic groups on all subscales. Furthermore, correlations with depression (SDS), anxiety (STAI), and functional impairment (SF-36) demonstrated strong convergent validity.

CONCLUSIONS: This study provides support for the MFI-20 as a valuable tool when used in chronically unwell and well populations. It also suggests that the MFI-20 could serve as a complementary diagnostic tool in fatiguing illnesses, such as CFS.

Source: Lin JM, Brimmer DJ, Maloney EM, Nyarko E, Belue R, Reeves WC. Further validation of the Multidimensional Fatigue Inventory in a US adult population sample. Popul Health Metr. 2009 Dec 15;7:18. doi: 10.1186/1478-7954-7-18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2801470/ (Full article)

Validation of the energy index point score to serially measure the degree of disability in patients with chronic fatigue syndrome

Abstract:

BACKGROUND: A simple quantitative accurate method for assessing the degree of fatigue in patients with chronic fatigue syndrome (CFS) is necessary for physicians and patients. Severity of the disease and recovery can, thus, be assayed.

PATIENT AND METHODS: From February 1-27, 2007, fifty-six consecutive CFS patients at a single treatment center were simultaneously evaluated by the patient with the fatigue severity score (FSS), and by consensus of both patient and physician by the energy index (EI) point score.

RESULTS: The FSS and EI correlated well, 0.67, p<0.001.

CONCLUSION: The El point score is a validated reliable method to assess fatigue in CFS patients.

Source: Lerner AM, Beqaj SH, Fitzgerald JT. Validation of the energy index point score to serially measure the degree of disability in patients with chronic fatigue syndrome. In Vivo. 2008 Nov-Dec;22(6):799-801. http://iv.iiarjournals.org/content/22/6/799.long (Full article)

Fatigue rating scales: an empirical comparison

Abstract:

BACKGROUND: There has been limited research comparing the efficacy of different fatigue rating scales for use with individuals with chronic fatigue syndrome (CFS). This investigation explored relationships between two commonly-used fatigue rating scales in CFS research, the Fatigue Scale and the Fatigue Severity Scale. Theoretically, these scales have been described as measuring different aspects of the fatigue construct. The Fatigue Scale was developed as a measure of the severity of specific fatigue-related symptoms, while the Fatigue Severity Scale was designed to assess functional outcomes related to fatigue.

METHODS: Associations of these scales with the eight definitional symptoms of CFS and with eight domains of functional disability were examined separately in: (1) an overall sample of individuals with a wide range of fatigue severity and symptomatology; (2) a subsample of individuals with CFS-like symptomatology, and, (3) a subsample of healthy controls.

RESULTS: Findings revealed that both scales are appropriate and useful measures of fatigue-related symptomatology and disability within a general population of individuals with varying levels of fatigue. However, the Fatigue Severity Scale appears to represent a more accurate and comprehensive measure of fatigue-related severity, symptomatology, and functional disability for individuals with CFS-like symptomatology.

Source: Taylor RR, Jason LA, Torres A. Fatigue rating scales: an empirical comparison. Psychol Med. 2000 Jul;30(4):849-56. http://www.ncbi.nlm.nih.gov/pubmed/11037093

Development of a fatigue scale

Abstract:

A self-rating scale was developed to measure the severity of fatigue. Two-hundred and seventy-four new registrations on a general practice list completed a 14-item fatigue scale. In addition, 100 consecutive attenders to a general practice completed the fatigue scale and the fatigue item of the revised Clinical Interview Schedule (CIS-R). These were compared by the application of Relative Operating Characteristic (ROC) analysis. Tests of internal consistency and principal components analyses were performed on both sets of data. The scale was found to be both reliable and valid. There was a high degree of internal consistency, and the principal components analysis supported the notion of a two-factor solution (physical and mental fatigue). The validation coefficients for the fatigue scale, using an arbitrary cut off score of 3/4 and the item on the CIS-R were: sensitivity 75.5 and specificity 74.5.

Source: Chalder T, Berelowitz G, Pawlikowska T, Watts L, Wessely S, Wright D, Wallace EP. Development of a fatigue scale. J Psychosom Res. 1993;37(2):147-53. http://www.ncbi.nlm.nih.gov/pubmed/8463991