3. CUA
• Pharmacoeconomists sometimes want to include a measure of
patient preference or quality of life when comparing competing
treatment alternatives.
• Cost-utility analysis (CUA) is a method for comparing treatment
alternatives that integrates patient preferences and HRQOL.
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4. CUA….
For pharmacotherapy decisions:
• various factors like patient preferences, patient satisfaction, impact
of disease and Rx of disease on a patient's health related QOL are
applied in PE.
QOL: the assessment of functional effects of illness and its consequent
therapy as perceived by the patient.
Expressed as emotional, physical or social impacts on patients
QOL can be measured with the help of structured questionnaires
filled by patients.
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5. CUA….
• Often the utility measurement used is a quality-adjusted life year
(QALY) gained.
• QALY is a common measure of health status used in CUA, combining
morbidity and mortality data.
• Results of CUA are also expressed in a ratio, a cost-utility ratio (C:U
ratio).
• The preferred treatment alternative is that with the lowest cost per
QALY (or other health-status utility).
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7. CUA….
When to use CUA
Health-Related Quality of Life is the important outcome
Programmes affect both mortality and morbidity and you want to
combine both effects
Programmes affect wide range of outcomes and you want common unit
for comparison
when comparing programs and treatment alternatives:
that are life extending with serious side effects (e.g., cancer
chemotherapy),
those which produce reductions in morbidity rather than mortality
(e.g., medical treatment of arthritis)
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8. CUA….
When not to use
Only have intermediate outcome data
Effectiveness data show outcomes are equivalent
Effectiveness data show dominance
Extra cost of obtaining utility values is itself not CE
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9. CUA….
• Cost-utility analysis is a special form of CEA.
• CUA tried to combine the quality and quantity of life in its outcome
measures.
What is the U in CUA?
Utility - It refers to level of satisfaction or usefulness that consumers
derive from the consumption of goods and services.
• Utility weights are necessarily subjective - they elicit an individual’s
preferences for, or value of, one or more health states.
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10. METHODS USED TO MEASURE AND ESTIMATE UTILITY
• The precise meaning of a given utility estimate is dependent on
the approach,
scaling method and
source of values used in its derivation
• There is little consensus as to which approach is preferred
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11. Components of utility measurement
I. Scaling method/ Measuring “Utility”
Rating scale
Standard gamble
Time trade-off
Person trade-off
II. Approach
• Direct
• Holistic or composite
• Generic multi-attribute utility (MAU)
instrument
iii. Source of values
• Patients
• Health care providers
• General public
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13. Time Trade-Off (TTO)
• Choice between two certain outcomes
• Years of life traded for quality of life
• Years of healthy life you would give up to avoid living in a state of
poor health
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14. Example
• You have arthritis (unable to do household and personal care tasks,
difficulty walking)
• Choose between living with arthritis for the next 10 years (followed by
immediate death) or living in full health for a shorter length of time
(followed by immediate death)
• Would you choose 1 year of full health (followed by death) or 10 years with
arthritis (followed by death)?
• Would you choose 9 years of full health (followed by death) or 10 years
with arthritis (followed by death)?
• ‘Flip-flop’ until “preference value” is found
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15. • Utility of Health State A is T/10
T is the number of years in full health
10 is the number of years in Health State A
If years in full health selected was 6
Utility (HSA)= 6/10 = 0.60
The better Health State A is, the less the years of healthy life you
would give up
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16. Standard Gamble (SG)
• Classical method of assessing preferences
• Choose between certain outcome and a gamble
• Conforms to axioms of expected utility theory
• Incorporates uncertainty, therefore better reflects real
treatment decisions
• If respondent is risk neutral then utilities from SG should be
the same as from TTO
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18. • You have end-stage renal disease and face the prospect of
being on dialysis for the remaining 40 years of your life
• You are offered a hypothetical intervention (e.g. a xenograft)
that will involve the gamble:
Immediate return to full health (probability = p)
Immediate death (probability = 1- p)
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20. Two means of obtaining “utility” weights:
1. Evaluation specific/’holistic’ measures – develop evaluation
specific (‘holistic’) description of health state and then derive
weight for that specific state directly by population survey.
2. Use ‘generic’ or ‘multi-attribute’ instruments – use
predetermined weights, based on combination of dimensions of
health yielding a finite number of health states/values
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21. • CUA:
‘cost per quality adjusted life year’,
‘cost per healthy year equivalent’ or
‘cost per disability adjusted life year’.
• Natural units cannot capture both outcomes
• We need other measures like DALY and QALY
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22. Limitations of CUA
• Measurement of utility is very time and resource intensive.
• Lack of consensus on measurement methods
In general, researchers agree that “choice-based” approaches
(e.g., standard gamble, time trade-off) are more appropriate.
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23. Life Years
• Simplest and widely used measure of health
• Used when the dominant gain from a change is extra life rather
than relief of pain or disability
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24. Concepts of Utility Measurement
A. Disability Adjusted Life Years (DALY)
Includes
• potential years of life lost due to premature death (YLL) and
• equivalent years of health life lost by virtue of being in state other
than good health (equivalent healthy years lost due to non fatal
condition)
DALY = YLL + YLD
The non fatal health outcomes
• are difficult to define
• contain various domain like mobility, anxiety, pain etc.
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25. DALYs measure the loss of life years in full health starting from a
standardized life expectancy (E.g. of 80 years for men and 82.5 years for
women).
Different weights apply to years lived in different ages.
• The top weight is assigned a year spent at the age of 25 years.
• The utility of an intervention is measured by the number of DALYs
prevented.
• DALYs are used, e.g., by the WHO to compare population health in
different countries.
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26. DALY calculation
• Calculate years of life lost due to each disease
• Calculate loss of quality of life of those living with each disease
• Apply weights to reflect social value of people at different ages
• Apply discount rate
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28. 2. Quality of life and Quality-Adjusted Life Years (QALYs)
• Number of years at full health that would be valued equivalently
to the number of life years as experienced.
• QALY = Utility x # years in health state
• One year at full health QALY = 1.0
• Death QALY = 0.0
• 3 years disabled (U =0.5) = 1.5 QALYs
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29. Two basic outcomes of health care QALY
1. Mortality
• Mortality benefit expressed as life-years gained
2. HRQL
• described in terms of the ‘health state’
• single value
• 0 (death) - 1 (good health) scale
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30. • The utility of an intervention is given by the number of QALYs gained.
• Respondent characteristics such as disease experience and
adaptation, age, nationality and even income have all been shown to
influence the valuation of a given health state.
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31. 3. Healthy-Years Equivalents (HYEs)
• Is based on ‘health profiles’.
• Individuals are asked how they evaluate the likely sequence of
health states caused by an intervention.
• In particular, they are asked how many years in perfect health
they would find equally attractive as the profile in question.
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32. How to measure QALY
Nottingham health profile
• Measures health status – yes / No – 36 statements on energy, pain
, emotion, social isolation and physical morbidity
• Seven areas of performance : employment , looking home, social
home and sex life, hobbies and holidays
Rossers Index
Others: SF-36, Quality of well being (eg. Asthma Quality of Life
Questionnaire), Euro Qol (EQ-5D), Health Utilities Index (HUI)
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33. EQ-5D
MOBILITY
1. I have no problems in walking about
2. I have some problems in walking about
3. am confined to bed
SELF-CARE
1. have no problems with self-care
2. have some problems washing or dressing myself
3. I am unable to wash or dress myself
USUAL ACTIVITIES (e.g. work, study, housework family or leisure activities)
1. I have no problems with performing my usual activities
2. I have some problems with performing my usual activities
3. I am unable to perform my usual activities
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34. PAIN / DISCOMFORT
1. I have no pain or discomfort
2. I have moderate pain or discomfort
3. I have extreme pain or discomfort
ANXIETY / DEPRESSION
1. I am not anxious or depressed
2. I am moderately anxious or depressed
3. I am extremely anxious or depressed
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36. QALY Procedure
• Identify possible health states - cover all important and
relevant dimensions of QoL.
• Derive ‘weights’ for each state.
• Multiply life years (spent in each state) by ‘weight’ for that
state
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39. Example: Incremental CU ratio
= Cost drug A - Cost drug B
QALY drug A - QALY drug B
= $20,000 - $16,000
2.6 QALYs - 2.0 QALYs
= $6,400 / QALY
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40. +
Advantage over CEA:
it can combine more than one measure of effectiveness or
both measures of mortality and morbidity into a single measure
Disadvantage:
absence of agreement in measuring utilities,
lack of standards for comparing QALY and
problems with the quantification of patient problems.
• Reserved for comparing programs and treatment alternatives whose
basic goal is improving QOL.
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43. • QALYs-example:
For example, a patient with a rare cancer will live for only 2 years
without treatment. A new treatment increases life expectancy by 2
years however; it is associated with adverse effects which decrease the
quality of life by 25%.
QALY??
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44. The QALYs is calculated thus;
• Life expectancy = 2 (survival without treatment) + 2 (gain in life
years due to treatment) = 4 years.
• Adverse drug reactions due to treatment = 0.25%
• Hence decrease in quality of life = 2 x 0.25 = 0.5 years.
• Thus net gain is 2 - 0.5 = 1.5 or 1.5 QALYS.
• Thus the net gain with the new treatment is 1.5 QALYs rather than 2
years.
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45. Another example…….
• Assume Life Expectancy=50
• Utility with mumps disease=0.8
• What’s the outcome measure ?
– QALY??=40!
• That is, U=0.8--->> 10 years with mumps infection = 8 years in
good health
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46. Issues Measuring Utilities
• Different methods Different results
• Cognitive burden
• Emotional / religious objections
• Biases in measurement
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Editor's Notes
combines both the quality and quantity of life. QALYs is the most commonly used in CUA
Utility weights Must: 1. Have interval properties 2. Be ‘anchored’ at death and ‘good health’
A given ‘utility’ is simply a number representing intensity of preference, relative to full health or full health for age (given a utility of 1) and death (with a utility of 0).
Risk attitude –choices involving gambles, person can be
•risk averse
•risk seeking
•risk neutral
–risk attitude affects the utility value obtained from the gamble
is the product of the length of life (e.g., the additional years of life gained by taking a drug) and the patient’s assessment of the quality of health during that period of time, or the utility of the health status, to which people in this field refer.
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).
In the DALY concept, the QOL is assessed by experts, whereas in the case of QALYs and HYEs concepts, evaluation is by potential or actual patients.