What is the QALY?
The QALY is defined by the National Institute for Health and Clinical Excellence (NICE) as
measure of a person’s length of life weighted by a valuation of their health-related quality of
life. A quality-adjusted-life-year (QALY) takes into account both the quantity and quality of life
generated by healthcare interventions.
The QALY is expressed by this equation: QALY= UxT being the T the life years gained and the U
the quality of those years.
On one hand, the quantity of life is a type of measure to assess if people are alive or not. On
the other hand, quality of life is focused on the person´s health status. Quality could be valued
between 0 and 1. In this scale, the zero value is the death stage and one is the perfect health.
In the middle of this scale, there are different statuses of health.
One example of different questions to assess health condition is the EQ-5D test. It is formed by
five dimensions and has three levels: no problem, some problems and major problems.
Mobility
Pain/discomfort
Self-care
Anxiety/depression
No problems
walking about.
No pain or
discomfort.
No problems
with self-care.
Not anxious or
depressed.
Some problems
walking about.
Moderate pain
or discomfort.
Some problems
washing or
dressing.
Moderately
anxious or
depressed.
Confined to bed.
Extreme pain or
discomfort
Unable to wash
or dress self.
Extremely anxious
or depressed.
Usual activities
No problems in
performing
usual activities.
Some problems
in performing
usual activities.
Unable to
perform usual
activities
The patient is the responsible of giving a score in this test between 0 and 1. One year of
perfect health will take a score of 1 and it generates one QALY, whereas one year in a health
state valued at 0.5 is regarded as being equivalent to half a QALY. Thus, an intervention that
generates four additional years in a health state valued at 0.75 will generate one more QALY
than an intervention that generates four additional years in a health state valued at 0.5.
For example, if we apply the previous equation we will get this result:
Intervention Years gained
A
4
B
4
Quality score
0,75
0,5
QALY
4x0,75= 3
4x0,5=2
So the intervention A is the best alternative, because it gets a higher value of QALYs.
QALYs provide a common currency to assess the extent of the benefits gained from a variety of
interventions in terms of health- related quality of life and survival for the patient. They are
used to assess the effectiveness of interventions and are combined with the costs incurred in
providing the interventions to generate cost-utility ratios in a cost-utility analysis. A cost-utility
analysis is performed in the same way as a cost-effectiveness analysis except that the unit of
effectiveness is quality-adjusted-life-years (QALYS). A cost-utility ratio is the difference
between the costs of two interventions divided by the difference in the QALYs they produce.
However the QALY have some disadvantages as a measure method of quality of life:
1. It is hard to understand the results by uneducated people and is needed the
intervention of an expert.
2. The development of the test is not clear and in some cases is needed a previous
explanation before doing the test.
3. Sometimes the outcomes are not reliable.
4. The test is designed only for chronic diseases, what happens in acute diseases?
5. The test is not equal for all population
QALYs and cost–utility analysis provide additional information for decision-makers as they
grapple with addressing the healthcare dilemma of where to allocate resources to generate
the maximum health benefits for their communities and society as a whole.