Validation of the German version of the Cancer Fatigue Scale (CFS-D).

Fatigue is a very important factor determining the quality of life in patients with malignancies. Cancer fatigue occurs with anaemia, during and after chemo- or radiotherapy and in patients with advanced tumours. The Cancer Fatigue Scale (CFS) is a three-dimensional inventory with 15 items which was originally developed in Japan. We present the results of a validation study of the German version (CFS-D) of this instrument. The CFS-D was administered to 114 participants in a matched-pair study. In total, 57 (41 women) of the participants had malignant conditions, and 57 (41 women) were healthy volunteers. The Fatigue Numerical Scale was used to test convergence. The physical and performance status of the cancer patients was assessed by the Karnofsky-Index. Criteria for testing multidimensionality were the Hospital Anxiety and Depression Scale, and the questionnaire on autonomic regulation. We generated a three-dimensional inventory of the CFS-D with the subscales physical fatigue/vitality, cognitive and affective fatigue. The reliability results for the complete scale: Cronbach's alpha: r(alpha) = 0.94, retest reliability: r(rt) = 0.82. The convergence criteria correlate between r = 0.44-0.65 (all P < 0.001). The CFS-D is highly reliable and has construct validity in relation to other measures.