Define a Quality-Adjusted Life Year (QALY).

• A. A unit of healthcare spending.
• B. A measure combining length and quality of life; one QALY equals one year in perfect health.
• C. A measure of patient satisfaction.
• D. A unit of hospital bed days.

Answer: (B)

A QALY combines how long someone lives with how good or bad their health is during that time. It weights each year of life by a value between 0 and 1 that reflects health-related quality of life. So one year in perfect health equals 1 QALY; a year lived in a health state valued at 0.6 equals 0.6 QALYs, and two years at 0.8 quality equals 1.6 QALYs. This single metric lets us compare interventions by looking at the cost per QALY gained in cost-utility analyses. It’s not about spending, patient satisfaction, or hospital bed days.