What is a Cost-Effectiveness Acceptability Curve (CEAC)?

• A. A curve showing the relationship between costs and effectiveness over time.
• B. A curve showing the probability that an intervention is cost-effective across varying WTP thresholds.
• C. A curve plotting utilities against costs.
• D. A curve depicting budget impact.

Answer: (B)

A Cost-Effectiveness Acceptability Curve shows how confident we are that an intervention is cost-effective as you change the amount you’re willing to pay for a unit of health gain. This comes from probabilistic sensitivity analysis, where many simulations with different input values are run. For each possible willingness-to-pay threshold, you see what fraction of these simulations conclude the intervention is cost-effective, and you plot that fraction against the threshold. The result is a curve that starts near zero at low thresholds and approaches one at high thresholds, illustrating decision uncertainty across different value-for-money settings. It’s not about costs and effects over time, utilities vs costs, or budget impact; it specifically maps the probability of cost-effectiveness across varying willingness-to-pay values.