Measuring fatigue in haemodialysis patients: The factor structure of the Chalder Fatigue Questionnaire (CFQ)

Abstract

IntroductionFatigue is common in haemodialysis (HD) patients, leading to poorer quality of life and patient outcomes. Given the complex and subjective nature of fatigue, and its overlap with sleep disturbances and depression, its measurement represents a challenge. Our aim was to evaluate the psychometric properties of the 11-item Chalder Fatigue Questionnaire (CFQ) in HD patients, including an assessment of the validity of the factor structure, internal reliability and discriminant validity with respect to functional impairment due to fatigue, psychological distress and comorbidity. MethodsData were evaluated for psychometric analysis from a published study investigating clinical and psychosocial correlates of fatigue among 174 HD patients. Confirmatory factor analysis was used to determine the factor structure using Weighted Least-Squares with Mean and Variance (WLSMV) adjustment estimation. Mplus 7.3 was used for the analysis. ResultsMental and physical fatigue factors correlated highly (r=.70, p<.01). A bi-factor model with one general fatigue factor, which incorporated three smaller group factors (mental, physical and weakness) had good model fit. The CFQ general factor explained over 85% of the common variance, had high internal consistency, and showed a moderate correlation with distress and a small association with comorbidity and functional impairment. ConclusionsThe CFQ can be summed up to a total fatigue severity score, representing a composite factor of physical and mental symptoms. Taking into consideration the good psychometric properties of the CFQ and its brief length, it should be used in future studies interested in measuring fatigue severity in HD patients.