Quality Adjusted Life Year (QALY)

Quality Adjusted Life Year (QALY) is a measure of how long an individual will live that is adjusted for their quality of life. One QALY is equal to 1 year of life in perfect health. A year in imperfect health is given a fractional score depending on the extent to which they are in pain, prevented from carrying-out daily activities or suffer from mental disturbance.

QALYs are calculated by weighting each year with a quality-of-life score (on a 0 to 1 scale). The quality of life score is often measured in terms of the person’s ability to carry out the activities of daily life, and freedom from pain and mental disturbance.