L14 Flashcards
How does cost estimation work for a cost-utility analysis (CUA)?
Consider costs of treatment/intervention/technology/cost due to consumption of other services, identify these and measure them, then value this by attaching ‘prices’ to them
Main reason we use QALYs?
Health is a very multi-dimensional concept (eg. life quality is important, not just being alive!)
What do QALYs do?
Relate health state and time spent in health state
What is a key difference between CEAs and CUAs?
CEAs use QALYs!
How do you calculate QALYs?
Sum of (Time in health state x QofL in that health state)
What must we do to use QALYs?
Derive a ‘preference based’ QofL
How do we derive a ‘preference based’ QofL?
Measure and describe the health state, then value it through people’s preferences between different presented health states
4 key methods for finding out people’s preferences over health states?
1) Rating scale
2) Standard gamble
3) Time trade-off
4) Multi-attribute utility systems
RTSM
Give an example of a rating scale type question, a pro of the system and two cons of it?
eg. if you had flu for a week, how would you rate your health on a scale of 0 to 1
PRO: easy to use
CON: subjective; dependent on situ of each respondent (eg. one with flu may be biased)
Low grounding in economic theory
Explain what a standard gamble type question is, a pro of the system and two cons of it?
Given a choice between a given health state or an alternative state which yields full health prob. (p) or death with prob (1-p) (ie. preference based utility of life)
Pros: based on axioms of utility theory
Cons: difficult for general public to understand
doesn’t fit for many diseases (only really for chronic ones)
Explain what a time trade-off type question is, a pro of the system and one con of it?
Choice between say 0.8 health for 100yrs or 1.0 health for 60yrs
Pros: compromise between simplicity and theoretical gains
Cons: Likely to be affected by ones time preference (ie. preference for good stuff now!)
Explain how a multi-attribute utility system (MAUS) works? (2 steps)
Step 1) health status measurement and clarification
Step 2) health status valuation is derived from general public
Explain an example of a MAUS? What are its 2 components?
EQ-5D (EuroQoL)
- 5Q survey that assesses people’s preference for QofL
- 2 components: Descriptive system and valuation set (tariff)
What are the 5 categories in the EQ-5D’s descriptive component?
Mobility, self-care, usual activities, pain/discomfort, and anxiety/depression
How does the EQ-5D assess its categories?
Asks a question from each category, response on a 5-level scale (ie. 1 to 5), then uses these responses to calculate what the person’s QofL is at that moment
What is the ‘tariff stage’ in the EQ-5D?
It is the stage which combines and calculates QofL from the individual answers - it maps all health states onto an index from 0 to 1
What is the QALY calculation?
Prognosis with treatment(treatment) - without treatment(control) = total gain in QALYs
5 areas of debate around QALYs? (ie. can be argued as problems with it)
1) Whose preferences should be used over different choices?
2) Should a QALY be the same for everyone? (eg. smokers/children/obese people?)
3) Suitable ‘end-of-life’ measure
4) Is a QALY broad enough? (does it measure utility or just health?)
5) Is a 0->1 scale realistic? (are some people in a state worse than death, ie. <0)
Why do QALYs not sit well with the public?
The public do not grasp the concept and tf pressure gov. to fund everything
Why may QALYs be an unsuitable end of life measure?
They drastically undervalue end of life valuations bc people don’t have many years left to add up QALY estimates for!
