A CONFIRMATORY FACTOR ANALYSIS FOR AN ADAPTED AND VALIDATED POLISH VERSION OF THE CHALDER FATIGUE QUESTIONNAIRE

Objectives: The Chalder Fatigue Questionnaire (CFQ) was developed to measure fatigue in 2 dimensions: physical and mental. The aim of the study was to translate, adapt and evaluate the psychometric properties of the Polish version of the CFQ (CFQ-PL). Material and Methods: The process of translation was conducted using a forward and backward translation procedure. After cultural adaptation, the psychometric properties of the CFQ-PL were evaluated. Participants of the study were healthy individuals: medical students (N = 304) and pregnant women (pregnancy without complications, N = 925). The reliability and validity were estimated using fatigue numerical rating scales, the Beck Depression Inventory and the State-Trait Anxiety Inventory. To examine the factor structure of the CFQ-PL, a confirmatory factor analysis was conducted. Results: The internal consistency of the CFQ-PL was similar to the original version (Cronbach's a 0.85-0.91). Statistically significant correlations between the CFQ-PL and the current fatigue level, average fatigue and the sleepiness level (measured using numerical rating scales), as well as the intensity of depression and anxiety symptoms, all confirming the validity of the adapted scale. Using a confirmatory factor analysis, it was determined that a 1-factor model did not fit the data well. A 2-factor model with a correlation between mental and physical factors fitted better than the 1-factor model, yet fit indices revealed a poor fit. Using a 2-factor model with added covariance between items - 1 (problems with fatigue), 2 (resting more), 9 (slips of the tongue), 10 (finding the correct word) - resulted in acceptable fit indices in both groups of participants. Conclusions: After the process of translation, adaptation and validation of the CFQ-PL, it is now available for use under Polish conditions. This study provided evidence for structural validity of the 2-factor model of the 11-item version.