Quality-Adjusted Life Years (QALY)

Definition

In cost-utility analyses in the field of health economics, a recurring problem is to find an appropriate way of expressing and quantifying the health‐related effects of medical interventions. The QALY concept was developed in health economics as an important standard measure for describing the outcome of medical interventions in a manner allowing comparability. QALYs, or “quality-adjusted life years”, basically constitute a pragmatic approach to description of the health-related effects of medical interventions and assessment of the efficacy of a given therapy, in terms both of quality (improvement of the patient's quality of life) and of quantity (prolongation of life). Both effects are combined in QALYs, life expectancy being weighted by a factor q, a standardized quality index in which 1 represents perfect health and 0 death. The QALY concept also permits comparison of different interventions: QALY tables set out the comparative cost of various interventions per...