Abstract
Although fatigue is the most frequent complaint in cancer patients, there is no universally accepted definition. This thesis presents a series of studies whose aims were definition of cancer-specific fatigue and the development of an instrument which had the capacity to discriminate levels of fatigue in different groups of cancer patients. The first study explored the concept of fatigue by comparing the personal experiences of cancer patients (n=20) with those of healthy individuals (n=20). Using grounded theory, themes emerged which classified fatigue into physical, affective and cognitive components. Differences were found in the expressions used by the two cohorts, particularly in relation to the physical sensations experienced. The descriptors generated by cancer patients were compared with those used in the currently available fatigue instruments and illustrated considerable differences in content. They were therefore used to develop a new fatigue instrument - the Fatigue Assessment Questionnaire (FAQ). The second study tested the reliability and feasibility of the FAQ in a nonrandomised, prospective, cross-sectional study of cancer patients (n=77) and healthy individuals (n=77). It was found to discriminate between fatigue experienced by cancer patients and that experienced by healthy individuals. A tentative step-like theoretical explanation for the production, perception and expression of fatigue proposed at the end of study one was supported by factor analysis. It led to minor adaptations of the instrument. The third study subjected the FAQ to further validity testing. Four hundred and ninety-nine cancer patients with a variety of tumour types and stages were included in a prospective, non-randomised, cross-sectional study. Factor analysis supported the theoretical framework and led to modifications which resulted in a multi-dimensional, 20-item instrument. The FAQ discriminated significantly different levels of fatigue and the distress that it caused in patients with metastatic cancer, patients with localised cancer and patients whose disease was in remission. High levels of fatigue were mainly associated with advanced stages of cancer, in combination with high levels of depression. The closing chapter discussed issues for further research and implications for practice.