Quality Adjusted Life Years And Health Utilities

Front 1

The relationship between quality of life and health utility?
The ratio commonly looked at is the cost/health utility. The most common health utility measure looked at is quality of life. This is the gold standard. Cost / QALY

Back 1

Health Utility - Refers to the preferences individuals or society place on any specific health outcome relative to other possible outcomes. The value we place on our health.
The idea is that you need to consider the patient values their treatment and quality of life. Do they prefer that outcome. The outcome becomes their utility.
Utility is used because you can convert it to a QALY and is a common denominator in CUA.

Front 2

QALY

Back 2

life years gained from a medical treatment adjusted for the patients quality of life during a specific time period.
Quality of life is measured and then when it is scored, the scoring is weighted according to the patients preference for that quality of life state.
Each health utility obtained for each for each year of specified time period is summed to yield QALYs.

Front 3

"You take a utility instrument (questions about the person qol) and when you score this instrument, you don't get a quality of life score. You get a utility weight because based on how someone responds to the items, then in the scoring you weight the score according to the patient preference for that qol state and that state and you output you get when you score a utility tool is called UTL's. If you administer the tool over one year, you get UTL's over one year or a QALY. If the study is less than 1 year you keep it in the unit of the UTL. Greater than one year you express it in QALYs.

Back 3

DALYs vs QALYs
DALYs measure morbidity
Somewhat similar concepts
DALY - evaluating the health of different populations (ghana vs thailand for major chronic diseases in terms of disease burden)
You are measuring the years of life LOST due to disability or premature death.
Health professional panel at the WHO determined the weights of the disability
Used by the WHO primarily, but some US research

Front 4

QALY - You are not looking at disease in a population, but the outcome of medical interventions, one treatment vs another.
Measures the life GAINED from choosing one treatment over another treatment.
Weight is provided by patients - patients should be the deciders of what treatment they prefer
Used by the UK and are growing in other countries like the US

Back 4

True or False - DALYs are used to compare quality of life impacts of competing treatment alternatives

False - QALYs do this
***Intentionally making turning point questions harder...***

Front 5

How are QALYs obtained?

Back 5

Step 1: Develop a utility survey which ask about physical, emotional, and social well being and captures these resulting health states in a range from completely healthy to death
Looks like a quality of life instrument and you want to make sure you have a range of healthy to unhealthy.

Front 6

Step 2: Complete a Valuation Study to obtain utility weights for the possible health states in the survey. - Ask people to value the health states that are possible to achieve in your survey.
SF-36 is a great quality of life tool, but has too many questions for utility measurement. They cut out all but 6 for this and call it SF-6.

Back 6

Step 3: Administer the survey to a population of interest

Front 7

Step 4: Apply the weights obtained from the Valuation Study to the health states reported in your population of interest.
The utility that is gained is reported in UTL's.

Back 7

Step 5: Sum the utility gained/lost over a period of one year to obtain QALYs.

Step 1 and 2 are generally done by researchers that are experts in the field of utilities.

Outcomes researchers then apply the tool in the field

Front 8

EQ - 5D (5 dimensions)
Mobility
Self-care
Usual activity
Pain/Discomfort
Anxiety/Depression

Back 8

You pick, no, some, or extreme problems in each dimension.
If you have no problems, you score 1 + 1 +1 + 1 + 1 = 5

Front 9

Commonly used Health Utility Surveys

Back 9

EQ-5D
Health Utilities Index
SF-6D (shortened SF-36 to help get utilities out of)

Front 10

EQ-5D

Back 10

3 levels of health for each of the 5 dimensions (no, some, extreme health)

Front 11

Question: What is the health utility associated with each possible combination of EQ-5D responses?

Back 11

You have to know how much weight each response in the combination carries.
In other words, how much is health utility in saying you have impaired social function, or impaired usual activities. You obtain these weights by using a valuation study,

Front 12

The US Valuation Study - A study that created the weights for US population for EQ-5D. How do americans value each response.

Back 12

So if someone picks 2/3 for mobility that correlates with a utility reduction of -0.146. You start at 1 with perfect health. A choice of 3 in mobility reduces utility by -0.558.
Moderate or severe impairment in any of the 5 dimensions reduces your utility.

Front 13

A health state of 11111 correlates with a health utility of 1. The more 2's and 3's you pick, the lower utility value you will have.

Back 13

Calculating QALYs - Example 1
Age 0-40 Excellent health 0.95
Age 40-60 Good health; minor ailments only 0.90
Age 60-70 Osteoporosis; minor health discomfort 0.80
Age 70-82 Diabetes 0.70

Front 14

QALY = (40 x .95) + (20 x .9) + (10 x .8) + (12 x .7) = 72.4 years

Back 14

Even though they died at age 82 they had 72.4 years of full health.

Front 15

Valuation Studies: Method of getting the weights
a) Standard Gamble

Back 15

Preferred method
You describe a health state to them.
You then ask them what risk of death they are willing to bear to restore full health.

Front 16

Example: Treatment choice of those with kidney disease between transplant or dialysis. With the transplant, they could have Perfect health (probability P) or die (1- probability P). There is no risk of death with dialysis.

Back 16

This is very complicated to do in an objective manner, because how you would the description can have a heavy influence on the patient.

Front 17

b) Time Trade Off

Back 17

You ask the individual to report how many years of perfect health they would give up for a state number of years with illness.
Example: You will live the next 10 years with disabling arthritis. How many years of life are you willing to give up to have perfect health?
Choice 1 = perfect health for less years
Choice 2 = disabling health for more years
How many years would you be willing to give up to get that perfect health.

Front 18

c) Rating scale

Back 18

Most simple
Simple because you are describing the health state to them and asking them to point to a rating scale to tell you if 0 is their worst imaginable health and 1 is the best imaginable health, where you would point to in their given state. The first two are called backdoor approaches b/c you are obtaining preferences but not using a scale.
This is a front door approach

Front 19

Turning Point Question: Development of the weights assigned to health states in a utility tool is the objective of:

Back 19

Answer: A Valuation Study - Standard Gamble, Time - Trade off, Rating Scale

Validation studies are used to study validity of a instrument to make sure it measures what its supposed to measure

Front 20

Real World Considerations in Health Utility Measurement

Back 20

Ethical considerations
From whom should we obtain utility weights?
- Community at large? Not always the right population. Your population may have disease and value their health differently than the general population or the population your interested in may be of a different socioeconomic or cultural background. Weights are static and obtained from a valuation study, but these weights may not be relevant that you are fielding your tool in.

Front 21

Healthcare professionals?
- No, this goes against the whole idea of utility, which is to obtain patient preferences for their health.

Back 21

Patients with the disease of interest?
- No, not really feasible. Too many disease states to cover.

Front 22

Age itself contributes to declining utility therefore older populations inherently likely to experience greater utility losses.
- Older populations are more likely to experience greater utility losses. Their scores may go down just because of aging.

Back 22

Utility measurement is not being used to give priority of those in worst health.
- Example: Those with cancer have really low utility values and maybe those should be focused on? No this is not done currently

Front 23

c) Rating scale

Back 23

Most simple
Simple because you are describing the health state to them and asking them to point to a rating scale to tell you if 0 is their worst imaginable health and 1 is the best imaginable health, where you would point to in their given state. The first two are called backdoor approaches b/c you are obtaining preferences but not using a scale.
This is a front door approach

Front 24

Turning Point Question: Development of the weights assigned to health states in a utility tool is the objective of:

Back 24

Answer: A Valuation Study - Standard Gamble, Time - Trade off, Rating Scale

Validation studies are used to study validity of a instrument to make sure it measures what its supposed to measure

Front 25

Real World Considerations in Health Utility Measurement

Back 25

Ethical considerations
From whom should we obtain utility weights?
- Community at large? Not always the right population. Your population may have disease and value their health differently than the general population or the population your interested in may be of a different socioeconomic or cultural background. Weights are static and obtained from a valuation study, but these weights may not be relevant that you are fielding your tool in.

Front 26

Healthcare professionals?
- No, this goes against the whole idea of utility, which is to obtain patient preferences for their health.

Back 26

Patients with the disease of interest?
- No, not really feasible. Too many disease states to cover.

Front 27

Age itself contributes to declining utility therefore older populations inherently likely to experience greater utility losses.
- Older populations are more likely to experience greater utility losses. Their scores may go down just because of aging.

Back 27

Utility measurement is not being used to give priority of those in worst health.
- Example: Those with cancer have really low utility values and maybe those should be focused on? No this is not done currently

Front 28

Utility measurement does not account for qualitative differences in outcome
- When you plot someone's utility change over time, you can see whether or not their health status changes and you can see if it changes if they undergo a treatment. You may get the same utility value from a change that saves life vs improves status.

Back 28

Valuation studies are very difficult to do
- Large response burden and give the patients numerous scenarios
- Also very subjective - the rate they give you is based on their perception of their health and how they value it. This is difficult for most people. They have to read, and comprehend what you are telling them.