Qaly

Volume 1, number 6

What is a QALY?
Published by Hayward Medical Communications
● A quality-adjusted life-year (QALY) takes into account both quantity and the quality of life generated by healthcare interventions. It is the arithmetic product of life expectancy and a measure of the quality of the remaining life-years. ● A QALY places a weight on time in different health states. A year ofperfect health is worth 1; however, a year of less than perfect health life expectancy is worth less than 1. Death is considered to be equivalent to 0, however, some health states may be considered worse than death and have negative scores. ● 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 andsurvival for the patient. When combined with the costs of providing the interventions, cost–utility ratios result; these indicate the additional costs required to generate a year of perfect health (one QALY). Comparisons can be made between interventions, and priorities can be established based on those interventions that are relatively inexpensive (low cost per QALY) and those that are relativelyexpensive (high cost per QALY). ● QALYs are far from perfect as a measure of outcome, with a number of technical and methodological shortcomings. Nevertheless, the use of QALYs in resource allocation decisions does mean that choices between patient groups competing for medical care are made explicit and commissioners are given an insight into the likely benefits from investing in new technologies andtherapies.
Ceri Phillips
BSc(Econ) MSc(Econ) PhD

Senior Lecturer in Health Economics University of Wales, Swansea and Guy Thompson
BSc DipComPharm MRPharmS

Deputy Director, Welsh Centre for Postgraduate Pharmaceutical Education, University of Wales, Cardiff

www.evidence-based-medicine.co.uk

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What is
a QALY?
What is the concept behind QALYs?
The outcomes from treatments andother health-influencing activities have two basic components – the quantity and the quality of life. A QALY is the acronym for a quality-adjusted life-year, which embraces both of these components and is the arithmetic product of life expectancy and a measure of the quality of the remaining life-years.
It provides a common currency for measuring the extent of health gain that results fromhealthcare interventions and, when combined with the costs associated with the interventions, can be used to assess their relative worth from an economic perspective. The quantity of life, expressed in terms of survival or life expectancy, is a traditional measure that is widely accepted and has few problems of comparison – people are either alive or not. Quality of life, on the other hand, embraces awhole range of different facets of people’s lives, not just their health status. Even restricting the focus to a person’s health-related quality of life will result in a number of dimensions relating to both physical and mental capacity. A number of approaches have been used to generate these quality of life valuations, referred to as health utilities1; for example, standard gamble, time trade-offand the use of rating scales. The utilities that are produced represent the valuations attached to each health state on a continuum between 0 and 1, where 0 is equivalent to being dead and 1 represents the best possible health state, although some health states are regarded as being worse than death and have negative valuations (Figure 1). An example of an instrument that has produced a series ofhealth utilities is the EQ-5D, which is shown in Box 1. Patients are asked to indicate the extent to which they have a problem in five health areas. For each of the possible 245 health states utility scores were constructed from responses to a random sample of 3,000 people in the UK. An example of the utilities

Box 1. Using the EQ-5D
Scores for the EQ-5D are generated from the ability of the...