1.2. The fatigue scale named “Fatigue Impact Scale” The awareness of the impact of fatigue on patient’s quality of life (QOL) and the need to evaluate the effect of the different therapies on this parameter resulted in the development and validation of different questionnaires for the measurement of fatigue, i.e., the Fatigue Impact Scale (FIS), which has been shown to measure both, fatigue and treatment effect on fatigue (6-9).