Quality of life is widely used in society as a catchphrase for many aspects of the good life. However, in medicine quality of life has emerged as an outcome measure by which to justify different forms of treatment, evaluate different therapeutic approaches, identify the sequelae of disease or treatment and provide a basis for allocating resources to treatments judged to be most effective. From a clinical perspective, use of the construct quality of life is an attempt to recognise issues faced in the present, in contrast to quantity of life and survival parameters that are largely concerned with the future. For cancer patients, quality of life issues are of particular relevance due to the physical, psychological and social morbidity associated with the disease. The starting point for the research presented here was the identification of problems in the definition, measurement and analysis of quality of life and the data collected.
This research recognised two components to quality of life measurement that are often confused in the literature: domains and dimensions. Domains refer to the components that an individual or group of people recognise as contributing in some degree to quality of life. Dimensions are the different aspects of a domain that are measured and which relate to the value system of an individual. This research is unique in that the focus is on quality of life as defined from the perspective of people facing cancer rather than based on assumptions of quality of life from a research or clinical perspective. The aims of the study were concerned with the validity and reliability of quality of life assessment and the implications of the results for health professionals and for people with cancer.
The study sample included 153 cancer patients who were receiving care from an oncology or palliative care service. Recruitment was prospective and a longitudinal component followed participants over a period of approximately four weeks. The European Organization for Research and Treatment of Cancer core quality of life questionnaire (QLQ-C30) was used as an instrument suited for a heterogeneous cancer population at various stages of illness. Detailed interviews were conducted with participants on two occasions using qualitative and quantitative methods. The qualitative component was used to define quality of life, expand on the issues of importance to participants, identify the interrelationship between domains and consider how participants made global judgements of their quality of life. The quantitative component included the use of the QLQ-C30 integrated with additional measures of domain importance and perceived change. A card-sort exercise was also used to rank the importance of domains to the individual. The quantitative data enabled a consideration of a number of methodological issues including absolute and relative approaches to measuring domain importance, the validity of global measures of quality of life, the sensitivity and specificity of quality of life scales and responsiveness of the instrument to individual change. A theoretical issue related to the underlying combinations in summated scales is also outlined and explored.
The qualitative results showed that quality of life is a construct that has meaning for people with cancer. Participants described quality of life in terms of a number of common domains including autonomy, health and illness, social interaction, emotions and basic needs. Of particular importance to study participants was the autonomy domain, which has received less attention in previous research relating to quality of life. Autonomy was described in terms of being able to do what you want and maintaining normality despite the limitations imposed by illness. In this sense, quality of life was activity-orientated. These findings have particular relevance to health professionals who are concerned with the needs of patients and the major inhibitors of quality of life.
The quantitative data demonstrated that the importance of items varied at the individual and group level. Some items such as family (and relationships), daily activities and mobility were of high intrinsic importance for participants at all stages of disease, suggesting the integral part of these aspects to quality of life and the interdisciplinary approach required to identify and manage potential problems in these areas. Symptoms were responsible for short-term changes in quality of life, supporting the importance of symptom recognition and palliation in the clinical care of cancer patients. This research provides valuable insights into the development and use of tools, such as the card-sort exercise, that enable health professionals and patients to evaluate quality of life and consider individual priorities. Also discussed are the implications that arise from this research in terms of assessing quality of life over the disease course with a preventive approach to maintaining quality of life. This research provides evidence to suggest that quality of life should be evaluated in terms of its component domains and the importance of those domains to the individual, although the standard approach to item weighting was not supported. An integrated approach to quality of life assessment that goes beyond description and problem identification to educate and inform the person with cancer is recommended