Methodological issues related to assessing and measuring quality of life in patients with cancer: implications for patient care.

Consideration of quality-of-life issues by all members of the healthcare team is essential in caring for people with cancer. In cancer research, quality of life is generally classified as health-related quality of life or individual quality of life. This paper discusses the instruments used to measure quality-of-life outcomes, and the relevance of such findings for healthcare staff in planning and providing effective and patient-centred care. Visual analogue scales (VASs) and questionnaires are commonly used to measure quality of life; however, both types of instruments are criticized because the content may not be relevant to individual patients, and do not distinguish differences between statistical and clinical significances in the findings. Using a combination of questionnaires and VASs may overcome some of these criticisms. In order to interpret the difference between statistical and clinical significance of findings and the associated implications for patient care, a mixed-methods approach to data collection is recommended in quality-of-life studies. This provides meaning and understanding to the quantitative data and individual perspectives on patients' experiences of having cancer. Information from such studies may also be more effective in helping healthcare staff identify relevant issues when planning cancer care services at individual, local and national level.