[Fatigue in healthy and cancer patients. 1. A qualitative study on conceptual analysis]

Interest in fatigue-research has grown since the finding that fatigue/tiredness is the most frequently reported symptom of cancer and its treatment. But even though several authors have tried to conceptualise fatigue, its mechanisms are still poorly understood. The aim of this study was twofold: 1) to explore fatigue in cancer patients, inductively, and 2) to compare experiences of fatigue/tiredness of healthy individuals with that of cancer patients to identify cancer-specific fatigue/tiredness and related concepts.

A qualitative research strategy was adopted using a grounded theory approach. The prospective study took place in the Oncology Department of the Kantonsspital St. Gallen (Switzerland) with samples of 20 cancer patients and 20 healthy individuals. Unstructured, tape recorded interviews were conducted to collect data. The transcripts of the interviews were analysed using content analysis and constant comparison.

Different themes emerged between the two groups although both fitted a classification system, which categorised fatigue into physical, affective and cognitive expressions of fatigue/tiredness. Physical signs were more frequent than affective and cognitive signs in both groups. In the cancer patients, fatigue involved decreased physical performance, extreme, unusual tiredness, weakness and unusual need for rest, which was distinctly different for healthy persons. Affective and cognitive distress was also more prominent in cancer patients. Interestingly, the concept of malaise was not identified by either sample and not understood as an expression of fatigue by this German speaking population. Linguistic differences in the description of fatigue/tiredness between healthy and ill individuals revealed different perceptions of the phenomenon. A step-like theory, explaining the production of fatigue/tiredness was tentatively put forward involving nociception, perception and expression of tiredness.

The emerging concepts break tiredness/fatigue into expression of physical, affective and cognitive tiredness/fatigue. The experience is different between healthy individuals and cancer patients. Generalisability of data needs precaution but the results of the study identifies and clarifies ideas that might form an important basis for further, controlled studies.