Quality Adjusted Life Year (QALY) Scale

Name and Synonyms

Quality Adjusted Life Years Scale (QALYs).

Source Article

Weinstein MC.J Health Econ. 1988 Sep;7(3):289-90. 


A quality-adjusted life year (QALY) is a measure of a person's life expectancy and the quality of the remaining life-years. Although one treatment might help someone live longer, it might also have serious side effects. The Quality Adjusted Life Years (QALYs) is a measure of disease burden, including both the quality and the quantity of life lived. The method helps to measure these factors so that one can compare different treatments for the same condition.The QALY is based on the number of years of life that would be added by the intervention. The main objective of QALYs is to combine morbidity and mortality into a single weighted measure. Thus, a QALY gives an idea of how many extra months or years of life of a reasonable quality a person might gain as a result of treatment.
QALY scale is especially used in assessing the value for money of a medical intervention. QALY is an important and increasingly used economic measure of the relative impact of healthcare interventions. The QALY scale is for adult patients, and can be used for all diseases.

Structure / Content

There is no questionnaire. The QALY is calculated based on the expected duration of life and degree of diability.

Scoring Method

The years in perfect health is assigned the value of 1.0 down to a value of 0.0 for death. If the extra years would be lived in ill health, for example if the patient wheelchair-bounded, then the extra life-years are given a value between 0 to 1. It should be noted that, some health states may be considered worse than death and have negative scores.

An example*: Lets assume the patient A has a serious disease.

  • If he continues receiving standard treatment he will live for 1 year and his quality of life will be 0.4 (0 or below = worst possible health, 1= best possible health).
  • If he receives the new drug he will live for 1 year 3 months (1.25 years), with a quality of life of 0.6.

The new treatment is compared with standard care in terms of the QALYs gained:

  • Standard treatment: 1 (year's extra life) x 0.4 = 0.4 QALY
  • New treatment: 1.25 (1 year, 3 months extra life) x 0.6 = 0.75 QALY

Therefore, the new treatment leads to 0.35 additional QALYs (that is: 0.75 -0.4 QALY = 0.35 QALYs).

Assume that the cost of the new drug is $10,000, and standard treatment costs $3000.

  • The difference in treatment costs ($7000) is divided by the QALYs gained (0.35) to calculate the cost per QALY. So the new treatment would cost $20,000 per QALY.

Another example:

  • 3 years extra life @ 0.6 quality of life values 1.8
  • less 1 year @ reduced quality (1 - 0.6) 0.4
  • QALYs generated by the intervention 1.4

Language and translations

It is in US English. No translations.

Scientific Spine's Comment

QALY allow for the assessment of the value of an intervention in comparison with other interventions for the same disease.To ensure a health-related decision is fair, a standard method to compare different treatments and measure their clinical effectiveness is required. The QALY tries to satisfy that need. QALYs have been criticised because there is an implication that some patients will be refused or not offered treatment for the sake of other patients.


Weinstein MC.J Health Econ. 1988 Sep;7(3):289-90. 

* http://www.nice.org.uk/newsroom/features/measuringeffectivenessandcosteffectivenesstheqaly.jsp

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