Why is the discount rate used when evaluating long-term disease control programs?

• A. To reflect inflation only
• B. To adjust all values to a common present value considering the time value of money
• C. To increase future values
• D. To measure risk separately

Answer: (B)

The key idea is the time value of money: money available now is worth more than the same amount in the future because it can earn returns and because preferences favor present resources. In long-term disease control programs, costs often occur now while benefits (like reduced illness or deaths) unfold years later. Discounting brings future costs and benefits back to a common present value, so you can compare them on an apples-to-apples basis. The discount rate embodies the opportunity cost of capital and people’s time preference for money, shaping how much weight future health gains carry in the decision. A higher discount rate reduces the present value of distant benefits, potentially changing which program looks best; a lower rate does the opposite. Inflation effects can be incorporated, but discounting primarily reflects the trade-off between present and future values, not inflation alone or risk in isolation.