What unit is used in the commonly cited WTP threshold mentioned in the material?

• A. QALYs
• B. Life-years gained
• C. DALYs
• D. Symptom-free days

Answer: (A)

The main idea here is that a willingness-to-pay threshold is usually stated as cost per unit of health benefit, and the most common unit is a QALY. A QALY, or quality-adjusted life year, combines how long someone lives with how good or bad their health is during that time. One year in perfect health equals 1 QALY; if a year is lived in a health state with a utility of 0.6, that year counts as 0.6 QALYs. In cost-effectiveness analyses, we look at the incremental cost per additional QALY gained when comparing an intervention to alternatives. That makes QALYs the standard unit for expressing a WTP threshold.

Why the other options don’t fit as the usual unit: life-years gained measures only how long someone lives, not how well they live, so it ignores quality of life; DALYs are a burden measure rather than a unit used for deciding whether an intervention is cost-effective; symptom-free days are a specific health state metric and not the standard unit used in WTP thresholds. So the common threshold is expressed per QALY gained.