DUFS and DEFS: development, reliability and validity of the Dutch Fatigue Scale and the Dutch Exertion Fatigue Scale

The purpose of this study among patients with chronic heart failure (n = 138) was to develop and test both the Dutch Fatigue Scale (DUFS) and the Dutch Exertion Fatigue Scale (DEFS). Psychometric testing of these scales included measurement of internal consistency, construct validity and criterion-related validity. Statistical analyses of both scales showed sufficient reliability and validity. The DUFS (scale coefficient H = 0.48; Rho = 0.80; KR-20 = 0.79) is suitable as a measurement instrument for the diagnosis of fatigue and makes it possible to compare results of fatigue on the level of groups of patients. The DEFS (scale coefficient H = 0.61; Rho = 0.91; Cronbach's alpha = 0.91) can be used in clinical practice for the measurement of patients' exertion fatigue.