daytime fatigue – American ME and CFS Society

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

Abstract:

OBJECTIVE: To determine whether patients with the chronic fatigue syndrome have abnormalities of sleep which may contribute to daytime fatigue.

DESIGN: A case-control study of the sleep of patients with the chronic fatigue syndrome and that of healthy volunteers.

SETTING: An infectious disease outpatient clinic and subjects’ homes.

SUBJECTS: 12 patients who met research criteria for the chronic fatigue syndrome but not for major depressive disorder and 12 healthy controls matched for age, sex, and weight.

MAIN OUTCOME MEASURES: Subjective reports of sleep from patients’ diaries and measurement of sleep patterns by polysomnography. Subjects’ anxiety, depression, and functional impairment were assessed by interview.

RESULTS: Patients with the chronic fatigue syndrome spent more time in bed than controls (544 min v 465 min, p < 0.001) but slept less efficiently (90% v 96%, p < 0.05) and spent more time awake after initially going to sleep (31.9 min v 16.6 min, p < 0.05). Seven patients with the chronic fatigue syndrome had a sleep disorder (four had difficulty maintaining sleep, one had difficulty getting to sleep, one had difficulty in both initiating and maintaining sleep, and one had hypersomnia) compared with none of the controls (p = 0.003). Those with sleep disorders showed greater functional impairment than the remaining five patients (score on general health survey 50.4% v 70.4%, p < 0.05), but their psychiatric scores were not significantly different.

CONCLUSIONS: Most patients with the chronic fatigue syndrome had sleep disorders, which are likely to contribute to daytime fatigue. Sleep disorders may be important in the aetiology of the syndrome.

Source: Morriss R, Sharpe M, Sharpley AL, Cowen PJ, Hawton K, Morris J. Abnormalities of sleep in patients with the chronic fatigue syndrome. BMJ. 1993 May 1;306(6886):1161-4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1677618/ (Full article)