The assessment of chronic fatigue: psychometric properties of the Fatigue Scale (FS)

Background: The Fatigue Scale (FS) is a widely used instrument to assess severity and symptoms of chronic fatigue. Objective: The aim of the present studies consisted in the psychometric foundation of the German version of the FS. Methods: A total of N = 2510 of the German population (study 1) and N = 100 patients with psychosomatic/mental disorders (study 2) filled in the FS and additional scales (SOMS-7T, WHO-5, SF-8, FAQ). Results showed high internal consistency and retest-reliability of the fatigue severity score, confirmation of the 2-factor-structure and associations between fatigue and somatoform symptoms, well-being and quality-of-life. Conclusions: Based on its psychometric properties the FS seems to be an adequate instrument for the individual assessment and treatment evaluation of chronic fatigue.