People diagnosed with cancer or undergoing cancer treatment experience a wide range of symptoms. One of the most common symptoms experienced by cancer patients today is cancer-related fatigue. Cancer-related fatigue is a complex condition, recognised as a multidimensional construct and thought to be associated with a cluster of symptoms rather than occurring in isolation. Cancer-related fatigue is distressing and can persist beyond the treatment phase or the disease itself. Current understanding of cancer-related fatigue and its management is limited. Further developing our knowledge of cancer-related fatigue may lead to innovative means of improving the identification, prediction and management of this troublesome symptom. To this end, this thesis aims to: I) identify factors reported to have a relationship with cancer-related fatigue; II) examine the course of cancer-related fatigue during and after radiotherapy; III) determine a method of detecting clinically meaningful change in fatigue; IV) examine whether correlates of fatigue are consistent across all fatigue dimensions or whether each dimension has its own unique pattern of correlates; and, V) develop and trial a group-based educational intervention to target cancer-related fatigue. To address Aim I in this thesis, relevant literature was reviewed to identify factors which potentially influence cancer-related fatigue. Factors identified include underlying medical factors (biomedical mechanisms, disease-related factors, treatment-related factors and comorbid conditions); physical or behavioural factors (poor nutrition, decreased activity, sleep disturbance, pain); psychological factors (anxiety and depression); and sociodemographic factors (social support, employment and education). The range of inter-related factors identified makes cancer-related fatigue a challenging condition to manage. The factors associated with cancer-related fatigue were synthesized into the Fatigue Framework to provide a clinically useful format for health professionals working with people with cancer. The Fatigue Framework was used to guide the remainder of the research into cancer-related fatigue presented in this thesis. This research consists of two main studies; a prospective longitudinal cohort study (to address Aims II, III, IV) and a randomised controlled trial (to address Aim V). The first study in this research examined the factors and effects associated with cancer-related fatigue in a radiotherapy population (n=210). Patients undergoing radiotherapy were recruited for a single-centre prospective longitudinal cohort study. Participants were assessed using a battery of assessments at three time points, at the start of radiotherapy, the end of radiotherapy and six weeks after radiotherapy completion. The results of this study were used to address Aim II, to identify the pattern of fatigue over the course of radiotherapy. The level of fatigue reported was shown to significantly increase from start to the end of radiotherapy and then significantly decrease from the end of radiotherapy to six weeks post-treatment for each subscale of the MFI. The results of this study were also used to address Aim III, to determine a method of detecting clinically meaningful change in fatigue. Whilst there are many tools used to assess cancer-related fatigue, the Multidimensional Fatigue Inventory (MFI) was the assessment chosen for use in this research study and throughout this thesis. The MFI is one of the few fatigue assessments that takes the various clinical dimensions of fatigue into account and has established reliability and validity. However, unlike other fatigue assessments, there were no published minimal clinically important difference (MCID) criteria for its use in cancer populations. MCID criteria determine the smallest change in scores that can be regarded as important, allowing clinicians and researchers to interpret the meaning of changes in patients’ fatigue scores. Determination of the MCID was based on the relationship of MFI scores to four clinically relevant constructs: (1) treatment impact on fatigue, (2) health-related quality of life, (3) performance status and (4) occupational productivity. These constructs were used as external or anchor-based measures to determine a MCID for each sub-scale of the MFI. Multiple MCID criteria were identified through the first study, each from a different perspective based on the anchor-based construct used. However, a two-point reference for each MFI sub-scale was suggested as a generic MCID as it was most consistent across the anchors examined. The MCID criteria validated in this study allow better interpretation of changes in MFI sub-scale scores and allow effect size calculations for determining sample size in future studies. The MFI allows assessment of multiple dimensions of fatigue (general fatigue, physical fatigue, reduced activity, reduced motivation and mental fatigue). Minimal previous research had considered the differential effect of symptom correlates on individual dimensions of fatigue. The data of the prospective cohort study were further utilised to address Aim IV, to determine whether correlates of fatigue were consistent across all dimensions or whether each fatigue dimension had its own unique pattern of correlates. Results indicated that each dimension of fatigue was associated with a different pattern of correlates supporting the concept of multiple dimensions of fatigue. This enhanced understanding of fatigue could be used to guide the development of individually tailored interventions to target specific correlates of fatigue in affected domains, or group interventions to address all relevant fatigue correlates. Because fatigue is associated with multiple symptom correlates, it requires multi-focused symptom management. Education is a commonly recommended fatigue management strategy which can be used to target multiple symptoms simultaneously. There is a lack of information about the content and format used in education programs and the effectiveness of education in managing fatigue. The second study in this thesis addressed Aim V, to develop and trial a group-based educational intervention to target cancer-related fatigue. The study examined a group-based educational intervention (CAN-FIT) targeting cancer-related fatigue in radiotherapy patients. A pilot study of the intervention’s feasibility and acceptability indicated the intervention was acceptable to participants and its operation was feasible. Small modifications to program components were made based on participant feedback. A randomised controlled trial was then conducted to examine effectiveness of the CAN-FIT program and to ascertain the most effective timing for such an educational intervention. The study employed a factorial design and recruited 110 participants. Assessments were conducted at three time points, the start of radiotherapy, the end of radiotherapy and six weeks after the completion of radiotherapy. Results of the randomised controlled trial of CAN-FIT did not show a significant effect of the program on cancer-related fatigue levels, however the pre-radiotherapy education sessions were associated with significant increases in physical activity participation. Furthermore, the study demonstrated the delivery of education prior to radiotherapy was more effective than delivery after radiotherapy. This thesis successfully addresses its stated aims and provides a greater understanding of the concept of cancer-related fatigue. The results more clearly describe the course and correlates of fatigue and their relationship with the dimensions of fatigue. The MCID criteria for the MFI can be used in future research to evaluate outcomes and determine sample size in power calculations. The intervention trialled can be used in clinical practice to provide a low-resource intervention to improve activity levels without any subsequent change in fatigue in radiotherapy patients. Together these studies build upon current knowledge and provide directions for future research to address this difficult symptom.
| Identifer | oai:union.ndltd.org:ADTP/290229 |
| Creators | Amanda Purcell |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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