If an ICER equals the predetermined willingness-to-pay threshold, which statement best describes its cost-effectiveness assuming no major uncertainties or biases?

• A. It is considered cost-effective.
• B. It is considered cost-effective, provided there are no major uncertainties or biases.
• C. It is always cost-ineffective.
• D. No interpretation is possible.

Answer: (B)

The key idea is that the willingness-to-pay threshold represents the maximum value society assigns to one unit of health benefit. When the incremental cost per unit of health benefit (the ICER) exactly equals that threshold, the additional benefit is priced at the value society is willing to pay. If there are no major uncertainties or biases, this exact boundary means the intervention is cost-effective because it delivers a unit of benefit at a cost that matches the threshold.

In real analyses, uncertainty can sway interpretation, but under clean, uncertainty-free conditions, equality to the threshold is treated as cost-effective. That’s why the best statement is that it is cost-effective, provided there are no major uncertainties or biases.