1. Quality of life Assessment introduction
Jan J. v. Busschbach, Ph.D.
Department of Medical Psychology and Psychotherapy, Erasmus MC
Psychotherapeutic Centrum ‘De Viersprong’, Halsteren

2. Quality of life
“…. Health is physical, mental and social well-being and not merely the absence of disease or infirmity...”
World Health Organization, 1947
Extending health to well-being: Quality of life
What is the definition of quality of life?

3. Definitions of Quality of Life
Quality of life is the degree of need and satisfaction within the physical, psychological, social, activity, material and structural area (Hörnquist, 1982).
Quality of life is the subjective evaluation of good and satisfactory character of life as a whole (De Haes, 1988).
Health related quality of life is the subjective experiences or preferences expressed by an individual, or members of a particular group of persons, in relation to specified aspects of health status that are meaningful, in definable ways, for that individual or group (Till, 1992).
Quality of life is a state of well-being which is a composite of two components: 1) the ability to perform everyday activities which reflects physical psychological, and social well-being and 2) patient satisfaction with levels of functioning and the control of disease and/or treatment related symptoms (Gotay et al., 1992).
An individual’s perception of their position in life in the context of the culture and values systems in which they live and in relation to their goals, expectations, standards and concerns (WHO Quality of life Groups, 1993).

4. No clear definition because:
Many possible definitions
Multi-dimensionally
Subjective
Related to society
Researchers are free to choose
The notion of measuring the quality of life could include the measurement of practically anything of interest to anybody. And, no doubt, everybody could find arguments supporting the selection of whichever set of indicators to be his choice (Andrews & Withy, 1976, page 6)

5. No clear definition because:
Different origins of research
Clinical decision making: Does the patient benefit from the treatment?
Epidemiology (public health): what is the morbidity of the population?
Health economics: Is it worth the money?

6. Common items in definitions:
It is not the doctor who reports
Quality of life is subjective….
“Given its inherently subjective nature, consensus was quickly reached that quality of life ratings should, whenever possible, be elicited directly from patients themselves. “ (Aaronson, in B Spilker (Ed): Quality of life and Pharmacoeconomics in Clinical Trails, 1996, page 180)
Reports between proxies and patients vary.

7. Common items in definitions:
Health related
Multidimensional
Physical, psychological, social
Questionnaires
Standardize questions and response
Reproducible results: sciences
Quantify subjectivity
Operational defined
Like IQ and temperature.

8. How to measure quality of life form a clinical point of view?
Choose items
Are you able to walk one kilometer ?
Do you feel depressed ?
Choose response mode
Binary yes / no
Multiple (Likert) yes / at bid / hardly / no
Continuous (Visual Analogue Scale) Always ————X—— Never
Combine items to dimensions of quality of life
Sum up the items belonging to one dimension
Rescale sum on a scale from 0 to 100

9. Quality of life form a clinical point of view: profiles

10. The problem of multidimensionality
What if outcome conflict
e.g: better mobility, but worse roll emotional
On has to weight or combine outcomes
What if some patients dies?
Cancer therapy
Better quality of life, but higher mortality
Weight quality of life with mortality

11. Time Without Symptoms of disease and subjective Toxic effects of treatment
TWiST
Developed by Gelber (statistician)
In search for a typical “cancer” problem
Often prolonged life but also a reductions in quality of life
At the beginning (side effects)
At the end
Only count the days without symptoms of disease and subjective toxic effects of the treatment

12. Time Without Symptoms of disease and subjective Toxic effects of treatment

13. TWiST ignores differences in quality of life
Healthy = 1
Sick (dead) = 0
There is more to life than sick/health
Make scale 0..1
Quality adjusted TWiST (Q-TWiST)
Q-TWiST = QALY
Quality Adjusted Life Year

14. QALY Analysis Count life years Value (V) quality of life (Q)
1 = Healthy
0 = Dead
One dimension
Adjusted life years (Y) for value quality of life
QALY = Y * V(Q)
Y: numbers of life years
Q: health state
V(Q): the value of health state Q
Also called “utility analysis”

15. Which health care program is the most effective?
A new cancer therapy
Quality of life = 0.7
1.5 year survival
QALY = Y x V(Q) 
1.5 x 0.7 
1.05 QALY
The standard therapy
Quality of life = 0.8
1.0 year survival
1.0 x 0.8 
0.8 QALY

16. How to measure QoL for the calculation of QALYs?
One needs a uni-dimensional value of quality of life
Like the IQ-test measures intelligence
Ratio or interval scale
Difference between 0 and .8 must be 8 time higher than .1
Four popular methods have these pretensions
Visual Analog Scale
Time Trade-Off
Standard Gamble
Person trade-off

17. Value a health state You are in a wheelchair No pain or discomfort
No psychosocial problems

18. Visual Analogue Scale X VAS From psychological research
Normal health X
VAS
Also called category scaling
From psychological research
“How is your quality of life today ?”
“X” marks the spot
Response in centimeters
Rescale to [0..1]
Different anchor point possible:
Normal health (1.0) versus dead (0.0)
Best imaginable health versus worse imaginable health
Dead

19. Time Trade-Off TTO Wheelchair
With a life expectancy: 50 years
How many years would you trade-off for a cure?
Max. trade-off is 10 years
QALY(wheel) = QALY(healthy)
Y * V(wheel) = Y * V(healthy)
50 V(wheel) = 40 * 1
V(wheel) = .8

20. Standard Gamble SG Wheelchair Life expectancy is not important here
How much are risk on death are you prepared to take for a cure?
Max. risk is 20%
100% life on wheels = (100%-20%) life on feet
V(Wheels) = 80% or .8

21. Values differ N = 103 students

22. Comparisons of valuation methods (1)
Visual analogue scale
Easy
No trade-off: no relation to QALY
No interval proportions
Massive evidence
Much from other social sciences
Standard Gamble / Time trade-Off
Less easy
Trade-off: clear relation to QALY
Interval proportions
Much evidence
Especially in health economics

23. Comparisons of valuation methods (2)
Person Trade-Off
Difficult
Trade-off: unclear relation QALY
Include egalitarian aspects of health care
Unclear interval proportions
Very little evidence
Controversial results
Extreme value compression

24. Patient values seem high
Stensman
Scan J Rehab Med 1985;17:87-99.
Scores on a visual analogue scale
36 subjects in a wheelchair
36 normal matched controls
Mean score
Wheelchair: 8.0
Controls: 8.3

25. Response shift

26. Interpretation response shift
Thentest = true value
Saves trouble of pre-test
But….is the post-test still true?
Should we do a thenposttest as well?
Does this say that patient can not judge their own health?

27. Which patient should we ask?
Those with experience?
Who are they?
The amount of experience
Length of experience
Time since experience
Strength of relation with patient
No experience
Friends
No time at all
Family
Some time
Long
Self
Now recently distant never
All current patients

28. Quality of life in patients
When should we ask?
Which patients should we ask?
Response shift
Is a low quality of life a sign of
a low physical functioning?
an absence of the response shift?

29. The incomprehensible patient
Keeps on coming back to the clinic
Modifies social environment
Passive in own goals
Angry, depressed, suspicious
Low quality of life

30. Adaptation and quality of life
A low quality of life sign of low adaptation
Increase adoption will increase quality of life
A starting point for psychological therapy
A low quality of life
Malfunctioning of adaptation
Wrong coping strategy
Behavioral / peer group therapy
Personality disorder
More invasive therapy