[Measuring fatigue of cancer patients in the German-speaking region: development of the Fatigue Assessment Questionnaire].

UNLABELLED: Fatigue is recognised as one of the most frequent and distressing symptoms of patients with cancer. Whilst causal relationships mainly remain unclear, researchers meanwhile acknowledge its multidimensional nature. Causes and manifestations are complex and multifaceted and therefore, measurement in the past has been difficult. In recent years, some instruments have been developed in the English language. It is the aim of this article to describe the development of a new fatigue measurement instrument in the German language, the Fatigue Assessment Questionnaire. The following steps are described: 1. Concept analysis, 2. Identification of measurement criteria, 3. Comparison of these criteria with those described in the literature available, 4. Construction of a measurement scale, 5. Testing the new instrument, 6. Use of the instrument in a large study population. Steps 5 and 6 primarily deal with validity and reliability testing while step 6 also tests the hypothesis that patients with some types and stages of cancer suffer more from distressing fatigue than patients with other types and stages.
CONCLUSION: Validity of the measurement items in the Fatigue Assessment Questionnaire was supported by the fact that they were derived from qualitative interviews with cancer patients. The first test with 77 cancer patients and 77 healthy individuals led to small adaptations and the following study, including 592 cancer patients, supported the reliability and validity of the Fatigue Assessment Questionnaire. It was able to distinguish between different populations. Factor analyses supported the earlier generated model of physical, affective and cognitive fatigue. Internal consistency of the questionnaire was supported by the Alpha Coefficient 0.90 (Cronbach). A difference was found in physical tiredness for patients with different types of cancer (p = 0.008) but this was not the case for affective and cognitive tiredness. More fatigue feelings were experienced by cancer patients with advanced disease than by patients in remission and this was true for physical fatigue (p = 0.0001), affective fatigue (p = 0.01), cognitive fatigue (p = 0.02) as well as for fatigue intensity (p = 0.0001) and distress (p = 0.0001). This group of patients also experienced significantly higher levels of depression and anxiety (p = 0.0001). The Fatigue Assessment Questionnaire, developed in the German speaking part of Switzerland, can be used for further activities in the field of quality of life and nursing care in oncology. The instrument and a proposed scoring system are published as an addendum to this article.