Subtypes Of Fatigue Research Articles

Reply: Two types of fatigue in cancer patients

Sir, Giacalone et al (2012) present an interesting idea here in response to our paper on prevalence of fatigue in cancer patients (Singer et al, 2011). They assume that fatigue in our group of patients presents as two different types, cancer related and chronic, and that these types need different clinical management. Characteristics of chronic fatigue, in contrast to those of cancer-related fatigue, are that problems appear before the cancer diagnosis, and that they persist for a long period of time. Furthermore, certain characteristics like headache or difficulties concentrating are also specific for chronic fatigue. The latter is traditionally denoted as mental fatigue and was ascertained in our study in addition to general fatigue, on which we based our prevalence data. Although Giacalone's idea is interesting, we doubt that both types can be distinguished meaningfully in cancer trials or clinical routine. For example, even if fatigue symptoms were prevalent before the cancer diagnosis, we cannot assume for certain that these symptoms were unrelated to cancer, as the malignancy might have been developing for a long time before the clinical diagnosis was actually made. Another reason for scepticism is that, contrary to what Giacalone et al assume, the pattern of predicting factors of general and mental fatigue is very similar. We previously investigated that issue in a group of 646 cancer survivors (Kuhnt et al, 2009) and saw that both general and mental fatigue are related to the same variables. Thus, different ‘types' of fatigue could not be reliably classified in our sample of cancer survivors. Of course, this does not prove in any way that no subtypes of fatigue in cancer patients may exist. However, based on the conceptual considerations and previous empirical data, we have some doubts that such subtypes can be differentiated easily.

Fatigued breast cancer survivors: The role of sleep quality, depressed mood, stage and age

Cancer-related fatigue is associated with lower health-related quality of life and the majority of breast cancer survivors experience persistent fatigue after finishing treatment. The present study examines age, cancer stage, sleep quality and depressed mood as predictors of five dimensions of fatigue in 70 fatigued breast cancer survivors who no longer evidenced any signs of cancer and were finished with treatment. Discriminant function analyses were used to predict fatigue subgroup membership (higher, lower) from age, stage, mood and sleep for five subtypes: General, Mental, Emotional, and Physical fatigue, and Vigour. Significant discriminant functions were found for all subtypes. Findings suggest that age, staging, mood and sleep are all important predictors, but there are differential relationships when subtypes of fatigue are considered. Given current limitations in treating fatigue directly, interventions targeting mood and sleep should be considered as alternate approaches to reduce fatigue.