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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 300 400

Days sick of chemotherapy 10 150

Days sick of disease 100 30

TWiST 190 220

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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

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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?

04/20/23

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?

04/20/23

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).

04/20/23

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)

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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?

04/20/23

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)

04/20/23

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.

04/20/23

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

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Quality of life form a clinical point of view: profiles

0

10

20

30

40

50

60

70

80

90

100

Dimensions of Qaulity of life

Sco

res s

cale

d f

rom

0 t

o 1

00

Hospital pharmacist

General pop.

Hypertention

Diabetes II

Growth hormon def.

Depression

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Can profiles help? (1)

Symptoms Drug X Drug Y

Survival days 300 400

Days sick of chemotherapy 10 150

Days sick of disease 100 30

TWiST 190 220

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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?

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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 trade-

off

• Plus validated questionnaires– HUI, EuroQol EQ-5D, 15-D, AQoL, etc

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Value a health state

• You are in a wheelchair

• No pain or discomfort

• No psychosocial problems

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Visual Analogue Scale

• 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]

Dead

Normal health

X

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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– 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

Healthy

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.

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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 tableIntervention $ / QALYGM-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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0

10000

20000

30000

40000

50000

60000

70000

0 0.8 0.6 0.4 0.2 dead

Severity of disease in lost QALYs

Co

st p

er Q

AL

Y

20000 euro threshold

Increase threashold

Shifting threshold

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Practice

Proportional short fall

Onychomycosis 0.02Osteoporosis 0.08Symptomatic BPH 0.09Hypertension 0.26High Cholesterol 0.28Arteriosclerosis 0.55COPD 0.61Pneumococcal pneumonia 0.82Pulmonary hypertension 0.96Non-Hodgkin Lymphoma 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