Subjective Quality of Life Measures – General Principles and Concepts

Subjective quality of life (QOL) is becoming a standard health outcome measure especially for people with multiple, chronic, functional, psychological, or incurable illnesses. A good instrument is the pre-requisite of any measurement, which is in the form a questionnaire for QOL. This chapter reviews the concepts, principles, applications, scoring methods and selection criteria of subjective QOL measures to enable users to choose the most appropriate instruments for their purposes.

Quality of life (QOL) is a logical outcome measure of the effectiveness of modern health care much of which aims at relieving suffering and restoring normal living. The essential concepts of QOL measures are subjectivity, multi-dimensionality and well-being. Health-related quality of life (HRQOL) focuses on dimensions that are modifiable by health. General health perception, psychological well-being and functioning are essential dimensions of HRQOL while symptoms and vitality are important causative variables.

Quality of life is a latent variable that cannot be directly measured. It needs to be converted to indicators of its component dimensions and domains to be quantified. To serve the purpose, the indicators must be valid, important, representative and adequate. A QOL measure presents the indicators as items that can be rated on response scales, which are then presented as a profile domain scores or a composite index of quality of life.

Hundreds of QOL measures have been developed mostly for the assessment of HRQOL. Generic measures that are applicable to people with different health status are more suitable for population and comparative studies. Disease specific measures tend to have high sensitivity and are best used for evaluative purposes. Preference-based measures of health (PBMH) convert a multidimensional QOL state to a fractional index for the calculation of quality adjusted life years (QALYs) and cost-effectiveness. A critical appraisal of the nature and psychometric properties of a QOL measure can assure that it will meet the needs of the user.

Keywords

• Minimal Clinically Important Difference

• HRQOL Measure

• Scientific Advisory Committee

• Modern Health Care

• WHOQOL Group

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.