Psychometric Evaluation of the Korean Version of the Functional Assessment of Chronic Illness Therapy-Fatigue

Background The Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) instrument is a fatigue measure widely used on patients with cancer worldwide. The psychometric quality of the Korean version of the FACIT-Fatigue instrument has never been systematically evaluated. Purpose The purpose of this study was to assess the reliability and validity of the Korean version of the FACIT-Fatigue instrument. Methods This study used data collected from 170 patients with cancer and 120 healthy individuals. Internal consistency reliability was analyzed using Cronbach's alpha and item-total correlation. Construct validity was analyzed using confirmatory factor analysis, and known-group validity was tested using t tests. Convergent validity was analyzed using Pearson's correlation with pain and functional limitations. Predictive validity was analyzed using receiver operating characteristic curves. Results The Cronbach's alpha was .93 for the reliability evaluation, and the item-total correlation ranged from .27 to .84. In the construct validity evaluation, the bifactor model showed good fit (Q = 1.93, comparative fit index = .97, Tucker-Lewis index = .96, root mean square error of approximation = .05), indicating using the instrument's total score to be more appropriate than using the subscale scores (explained common variance = .76, omega = .95, omega(H) = .85, omega(H)/omega = .89). The group of patients with cancer showed significantly higher fatigue than the healthy subject group, showing known-group validity (t = -10.40, p < .05). Fatigue showed significant and strong correlations with functional limitations and pain (all ps < .001). The area under the curve was .81 (cutoff point = 40, Youden's index: 0.47, sensitivity: 77.60%, specificity: 73.04%), verifying that the instrument is predictive of higher fatigue severity in patients with cancer. Conclusions/Implications for Practice The Korean version of the FACIT-Fatigue instrument was shown to be reliable and valid. Its construct validity supports the use of the total scale score rather than the subscale scores.

Automated summary

The study assessed the reliability and validity of the Korean version of the FACIT-Fatigue instrument using data from 170 cancer patients and 120 healthy individuals. Results showed good internal consistency reliability, construct validity, and known-group validity, supporting the instrument's predictive ability for fatigue severity in cancer patients.