Interactive introduction in
Quality of life Assessment
• Jan J. v. Busschbach, Ph.D.
• Department of Medical Psychology and
Psychotherapy, Erasmus MC
– J.vanbusschbach@eramusmc.nl
– +31 10 4087807
• Psychotherapeutic Centrum ‘De Viersprong’,
Halsteren
– Jan.Busschbach@deviersprong.nl
– +31 164 632200
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New cancer therapy
Symptoms
Drug X
Drug Y
Survival days
Days sick of chemotherapy
Days sick of disease
TWiST
300
10
100
190
400
150
30
220
2
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
3
TWiST ignores differences in
quality of life
• TWiST
– Healthy = 1
– Sick (dead) = 0
• There is more to life than sick/health
– Make intermediate values
– Q-TWiST
» Quality of life adjusted adjusted TWiST
• How to scale quality of life?
• What is Quality of life?
4
Quality of life
• “…. Health is physical, mental and social wellbeing 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?
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).
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)
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?
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Common items in definitions:
• 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)
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.
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
– Multiple (Likert)
– Continuous (Visual Analogue Scale)
yes / no
yes / at bid / hardly / no
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
Quality of life form a clinical
point of view: profiles
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Can profiles help? (1)
Symptoms
Drug X
Drug Y
Survival days
Days sick of chemotherapy
Days sick of disease
TWiST
300
10
100
190
400
150
30
220
13
Can profiles help? (2)
• TWiST
– Healthy = 1
– Sick (dead) = 0
• There is more to life than sick/health
– Make intermediate values
– Q-TWiST
» Quality of life adjusted adjusted TWiST
• How to scale quality of life?
• What is Quality of life?
14
How to scale QoL for Q-TWiST?
• One needs a uni-dimensional value of QoL
– Like the IQ-test measures intelligence
– Rules out multi-dimensional questionnaires
• 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 tradeoff
• Plus validated questionnaires
– HUI, EuroQol EQ-5D, 15-D, AQoL, etc
15
Value a health state
• You are in a wheelchair
• No pain or discomfort
• No psychosocial problems
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Visual Analogue Scale
• VAS
Normal
health
– Also called category scaling
• From psychological research
• “How is your quality of life today ?”
• “X” marks the spot
X
– Response in centimeters
– Rescale to [0..1]
Dead
17
Time Trade-Off
• TTO
– Values Quality of Life in QALYs
– Quality adjusted life years
• 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
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Q-TWiST = QALY
• When health (QoL) is valued in years
– instead of of days….
• Q-TWiST = Quality Adjusted Life Years
– QALYs
• Q-TWiST invention of physicians
• QALY invention of economists
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Patient values include coping
• Stensman
Healthy
– 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
– Health controls: 8.3
• The patient perspective
does not work in Health
economics
Death
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The general public should be
informed…
• Valuing without knowledge makes no sense
– Thyroid Eye Disease
• Give description of the disease
A patient with bilateral thyroid
eye disease with upper lid
retraction and exophthalmos.
21
Which health care program is the
most cost-effective?
• A new wheelchair for elderly
–
–
–
–
–
–
Increases quality of life = 0.1
10 years benefit
Extra costs: $ 3,000 per life year
QALY = Y x V(Q) = 10 x 0.1 = 1 QALY
Costs are 10 x $3,000 = $30,000
Cost/QALY = 30,000/QALY
• Special post natal care
–
–
–
–
–
Quality of life = 0.8
35 year
Costs are $250,000
QALY = 35 x 0.8 = 28 QALY
Cost/QALY = 8,929/QALY
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QALY league table
Intervention
$ / QALY
GM-CSF in elderly with leukemia
235,958
EPO in dialysis patients
139,623
Lung transplantation
100,957
End stage renal disease management
53,513
Heart transplantation
46,775
Didronel in osteoporosis
32,047
PTA with Stent
17,889
Breast cancer screening
5,147
Viagra
5,097
Treatment of congenital anorectal malformations
2,778
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Implications shifting threshold
• QALY are weighted
• Weighted QALYs are maximized
– Health is no longer the only thing maximized
• Health status population will drop
• Differences in health will drop
– Egalitarian consideration are incorporated
• Burden of disease becomes a criteria
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Shifting threshold
70000
Cost per QALY
60000
20000 euro threshold
Increase threashold
50000
40000
30000
20000
10000
0
0
0.8
0.6
0.4
0.2
dead
Severity of disease in lost QALYs
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Practice
Proportional short fall
Onychomycosis
Osteoporosis
Symptomatic BPH
Hypertension
High Cholesterol
Arteriosclerosis
COPD
Pneumococcal pneumonia
Pulmonary hypertension
Non-Hodgkin Lymphoma
0.02
0.08
0.09
0.26
0.28
0.55
0.61
0.82
0.96
0.97
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CE-ratio by equity
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Conclusions
• Quality of life can be valued in
– Profiles
» Psychometric approach
– Unidimensional scaling
» Health economics
• Different perspective
– Societal
– Patient
» Coping
• Quality of life definition
– Operational defined
• Quality of life can moderate cost-effectiveness
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