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.
KeywordsMinimal Clinically Important Difference HRQOL Measure Scientific Advisory Committee Modern Health Care WHOQOL Group
List of Abbreviations:
- COOP/WONCA Charts
The Dartmouth Corporation Functional Health Assessment Charts/World Organization of Family Doctors
European Quality of Life-5 Dimension
Health Utilities Index-Mark 3
minimally important difference
preference-based measures of health
patient reported outcome
quality adjusted life years
quality of life
standard error of measurement
The Medical Outcomes Study 12-item Short-form Health Survey
The Medical Outcomes Study 36-item Short-form Health Survey
sickness impact profile
standardized response mean
visual analogue scale
World Health Organization Quality of Life Assessment Instrument
- Aaronson NK, ERORTC Study Group on Quality of Life.(1993). J Natl Cancer Inst. 85: 385–376.ERORTC Study Group on Quality of LifeGoogle Scholar
- Bland JM, Altman DG. (1986). Lancet. I: 307–310.Google Scholar
- European Medicines Agency Evaluation of Medicines for Human Use (EMEA). (2005). http://www.emea.europe.eu/pdfs/human/ewp/020595en.pdf.
- FDA. (2006). Guidance for Industry-Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims. http://www.fda.gov/cder/guidance/
- Kaplan R, Andersen R. (1996). In Spilker B (ed.) Quality of Life and Pharmacoeconomics in Clinical Trials. Lippincott-Raven, Philadelphia, PA, pp. 309–322.Google Scholar
- MAPI Research Trust. (2007). PROQOLOD. http://www.proqolid.org/proqolid.
- McDowell I, Newell C. (1996). Oxford University Press, New York.Google Scholar
- National Institute for Clinical Excellence (NICE). (2004). http://www.nice.org.uk/niceMedia/pdf/TAP_Methods.pdf.
- Oh S, Ku JH. (2006). Qual Life Res. 493–501.Google Scholar
- Petrie KJ, Weinman J, Sharpe N, Buckley J. (1996). Br Med J. 312: 1191–1194.Google Scholar
- Scholten JHG, van Weel C. (1992). Functional Status Assessment in Family Practice: The Dartmouth COOP Functional Health Assessment Charts/WONCA. Lelystad, Meditekst.Google Scholar
- Scientific Advisory Committee of the Medical Outcomes Trust. (2002). Qual life Res. 11: 193–205.Google Scholar
- Von Neumann J, Morgenstern O. (1953). Theory of Games and Economic Behavior. Princeton University Press, Princeton, NJ.Google Scholar
- Ware JE, Kosinski M. (2001). SF-36 Physical & Mental Health Summary Scales: A Manual for Users of Version 1. Quality Metric, Lincoln, Rhode Island.Google Scholar
- Ware JE, Snow KK, Kosinski M, Gandek B. (1993). SF-36 Health Survey Manual and Interpretation Guide. The Health Institute, NEMC, Boston.Google Scholar
- WHOQOL Group. (1993). Qual Life Res. 2: 153–159.Google Scholar
- WHOQOL Group. (1998). Soc Sci Med. 46: 1569–1585.Google Scholar