Critical care decisions in fetal and neonatal medicine: ethical issues
Appendix 8: The quality-adjusted life year (QALY)
A quality-adjusted life year (QALY) is a measure of both the quantity and the health-related quality of life gained by particular treatments or interventions. A year of perfect health is valued at 1 QALY, whereas a year expected to be spent at less than perfect health is valued at less than 1. Death is valued at zero using this measure, and some very serious health conditions may be considered to have negative scores. The main purpose of the QALY is to provide a common measure to assess the benefits gained from different health interventions. The incremental cost of providing 1 QALY can then be compared for different treatments in order to assess their cost-effectiveness.
For example:
Treatment A gives a patient 6 years in a health state valued at 0.5=3 QALYs
Treatment B gives a patient 6 years in a health state valued at 0.25=1.5 QALYs
Therefore, Treatment A generates 1.5 additional QALYs than Treatment B and this figure could be compared with the difference in costs between the two treatments.
A number of approaches have been used to generate the values for ‘health states’ (the figures0.5 and 0.25 in the example above). For example, a large sample of patients might be asked to indicate their state of health in terms of different domains, such as physical, social and cognitive function, psychological wellbeing, symptoms and pain. The answers could then be used to create average health-related quality of life scores for different conditions and health problems.
QALYs have various limitations, including the subjectivity of health-related quality of life assessments and variations in the way that the same person may assess their health-related quality of life at different times of their lives. It is also the case that once a person is in a particular health state, they may assess it differently than those who are not in that health state. Furthermore, little attempt has been made to assess the appropriateness of the QALY measure for childhood.
See Drummond MF, Sculpher MJ, Torrance GW, O’Brien B, Stoddart GL (2005) Methods for the economic evaluation of health care programmes, 3rd Edition (Oxford: Oxford University Press).