Quality-adjusted life years (QALY)

A measure of health outcome which looks at both length of life and quality of life.
QALYS are calculated by estimating the years of life remaining for a patient following a particular care pathway and weighting each year with a quality of life score (on a zero to one scale).
One QALY is equal to one year of life in perfect health, or two years at 50% health, and so on.
Cf. disability-adjusted life years