Reliability and Validity of the Modified Korean Version of the Chalder Fatigue Scale (mKCFQ11)

Abstract

Fatigue can accompany various diseases; however, fatigue itself is a key symptom for patients with chronic fatigue syndrome (CFS). Due to the absence of biological parameters for the diagnosis and severity of CFS, the assessment tool for the degree of fatigue is very important. This study aims to verify the reliability and validity of the modified Korean version of the Chalder Fatigue Scale (mKCFQ11). This study was performed using data from 97 participants (Male: 37, Female: 60) enrolled in a clinical trial for an intervention of CFS. The analyses of the coefficient between the mKCFQ11 score and the Fatigue Severity Scale (FSS), the Visual Analogue Scale (VAS) or the 36-item Short-Form Health Survey (SF-36) at two time points (baseline and 12 weeks) as well as their changed values were conducted. The mKCFQ11 showed strong reliability, as evidenced by the Cronbach’s alpha coefficient of 0.967 for the whole item and two subclasses (0.963 for physical and 0.958 for mental fatigue) along with the suitable validity of the mKCFQ11 structure shown by the principal component analysis. The mKCFQ11 scores also strongly correlated (higher than 0.7) with the VAS, FSS and SF-36 on all data from baseline and 12 weeks and changed values. This study demonstrated the clinical usefulness of the mKCFQ11 instrument, particularly in assessing the severity of fatigue and the evaluation of treatments for patients suffering from CFS.

Comparison of assessment scores for fatigue between multidimensional fatigue inventory (MFI-K) and modified chalder fatigue scale (mKCFQ)

“…These two PRO-based instruments have been translated into as many languages and are commonly used for assessments of the extent and severity of fatigue in patient and nonpatient populations [ 27 ]. This study analyzed the similarities and differences of fatigue-assessment data from the Korean versions of MFI (MFI-K) and modified CFQ (mKCFQ) [ 22 , 23 ] and aimed to produce important information regarding clinical choice and applications.…”

“…In general, fatigue is grouped into two categories, so-called physical and mental fatigue, in most studies [ 28 , 29 ]. The two instruments included in this study are also structured to distinguish between physical and mental fatigue assessments, and the responses to physical-mental fatigue-focusing questions were well differentiated from each other [ 22 , 23 , 30 ]. When we analyzed the correlation between the MFI-K and mKCFQ in the aspect of the physical and mental fatigue categories, each of the ‘physical’ and ‘mental’ fatigue scores correlated well between the two instruments, while the physical fatigue dimensions (‘general’, ‘physical’, and ‘activity’) were more highly correlated than the mental fatigue dimensions (‘mental’ and ‘motivation’, Table 2 ).…”

“…Extreme scoring is likely to cause an inability to discriminate between different groups [ 32 ]. Thus, the mKCFQ was designed on a 10-point Likert scale, which allows for the assessment of small fatigue differences among participants and changes after therapeutic interventions [ 21 , 23 ].…”

“…The Korean version of the CFQ (K-CFQ) was validated with healthy participants in 2018 [ 24 ], and we used the modified Korean version (mKCFQ, Additional file 1 : Table S1) in this study. To resolve the difficulty of assessment based on the comparison with the “usual” status, the mKCFQ was adapted to a 10-point Likert scale (0 = ‘not at all’ to 9 = ‘unbearably severe condition’), and its reliability and validity were confirmed with 97 CFS participants [ 23 ].…”

“…In fact, several clinical studies have adopted MFI and CFQ as primary assessment tools for fatigue and CFS patients [ 17 – 21 ]. The selection of an appropriate assessment tool is crucial in fatigue-related clinical studies, while the Korean version of the MFI (MFI-K) and modified CFQ (mKCFQ) were designed for assessing the therapeutic process of Koreans complaining of fatigue and CFS, and each of them was clinically validated [ 22 , 23 ]. However, no studies have been conducted comparing the characteristics of tools, particularly the most commonly used tools: MFI and CFQ.…”