6.3 Decision-making using the cost-effectiveness plane

The cost-effectiveness plane is a visual representation of the results of a cost-effectiveness analysis that plots:

• the difference in health outcomes (e.g. DALYs) on the x-axis
• the difference in costs on the y-axis.

Each point on the plane represents the comparison between two interventions.

Figure 6 shows an example of a cost-effectiveness plane for two hypothetical interventions, A and B. The plane is divided into four quadrants, each with a distinct interpretation:

• North-west (top left): Intervention A is more expensive and yields fewer health outcomes than Intervention B. Intervention A is therefore not cost-effective and does not need to be compared to a cost-effectiveness threshold. In health economics terminology, Intervention A is ‘dominated’ by Intervention B.
• North-east (top right): Intervention A is more expensive and yields more health outcomes than Intervention B. If the ICER of Intervention A versus Intervention B falls below the CET value, then Intervention A is cost-effective; if not, it is not cost-effective.
• South-east (bottom right): Intervention A is less expensive and yields more health outcomes than Intervention B. Intervention A is therefore cost-effective and does not need to be compared to a cost-effectiveness threshold. In health economics terminology, Intervention A is ‘dominant’ of Intervention B.
• South-west (bottom left): Intervention A is less expensive and yields fewer health outcomes than Intervention B. In this uncommon circumstance, the interpretation of the ICER versus CET is reversed: if the ICER of Intervention A versus Intervention B is above the CET value, then Intervention A is cost-effective; if not, it is not cost-effective.