Quality of life in palliative care: principles and practice.

In healthcare, most researchers and clinicians agree that quality of life (QOL) is related to symptoms, functioning, psychological and social wellbeing, and probably to a lesser extent to meaning and fulfillment. This multidimensional health-oriented concept has been named health-related quality of life (HRQOL). However, during end-of-life care spirituality and existential issues become more prominent, as well as family members' perception of quality of care. Outcome measures in palliative care require constructs that reflect the specific goals of palliative care, such as improving QOL before death, symptom control, family support and satisfaction, as well as patients' perceptions of 'purpose' and 'meaning of life'. It is generally recommended that internationally developed and validated patient-rated multidimensional questionnaires should be used when assessing HRQOL in research. However, 'multidimensionality', with often more than 10 possible outcomes, is a threat both to statistical analysis and clinical interpretation of data. Preferentially, a more limited number of outcomes based upon the research question(s) should be defined prior to data collection in the study protocol. The researcher needs to carefully evaluate the content of the questionnaire, in addition to other properties, such as the validity and reliability, before the final decision is made with regards to which instrument to use in a given study.