Why are QALYs commonly used in cost-utility analyses?

• A. They measure only costs
• B. They measure only quality
• C. They combine quality and quantity of life into one measure
• D. They measure only survival time

Answer: (C)

QALYs are used in cost-utility analyses because they capture both how long people live and how well they live, all in one metric. A QALY weights each year of life by the quality of that year, with 0 representing a state equivalent to death and 1 representing perfect health. By multiplying the length of time by this utility weight, you get a single number that reflects both survival and quality of life.

This lets us compare very different health interventions on the same scale. For example, one option might extend life by two years at a high health quality (0.9), equating to 1.8 QALYs, while another could add three years but with poorer quality (0.6), equal to 1.8 QALYs as well. The common QALY framework shows which option provides more value per cost, helping allocate scarce resources.

Other measures miss part of the picture: measuring only costs tells you about spending, not health outcomes; measuring only quality captures health preferences but not how long people live; measuring only survival time ignores the living quality of those years. QALYs integrate all that into a single, comparable outcome.