What does a cost-effectiveness acceptability curve (CEAC) show?

• A. A chart showing the distribution of cost data
• B. A forecast of future costs over time
• C. Probability an intervention is cost-effective across willingness-to-pay thresholds
• D. A measure of statistical significance of costs

Answer: (C)

Cost-effectiveness acceptability curves show the probability that an intervention is cost-effective across a range of willingness-to-pay per unit of health gain. They come from probabilistic sensitivity analyses that account for uncertainty in both costs and effects. On the x-axis is the willingness-to-pay per unit of effect, and on the y-axis is the probability the intervention is cost-effective at that threshold. For each WTP value, the curve reflects the proportion of simulations where the intervention has a positive net benefit (or where the ICER is below the threshold). This communicates how likely cost-effectiveness is as decision-makers’ willingness to pay changes. The other options describe cost distributions, future cost forecasts, or statistical significance of costs, not the probability of cost-effectiveness across thresholds.