The comparator(s) against which costs and effects are measured should accurately reflect the decision problem.

Importance to decision making
Identifying the comparator against which costs and effects will be measured is critical to ensuring that the economic evaluation accurately informs the decision problem facing the decision-maker.

The choice of comparator determines the comparative costs and benefits associated with the intervention being considered, and will therefore drive the incremental cost effectiveness ratio (ICER).

If the comparator does not reflect the decision problem, the economic evaluation will not be applicable to the decision-maker, as it will not represent the information needed to inform the particular decision. Use of a comparator that does not reflect the decision problem could lead to an inaccurate determination of cost-effectiveness, and facilitate bad decisions.


The method for determining relevant comparators may include:

  • The interventions that are currently available to the population (therapies in routine use) as defined in the decision problem
  • “Do nothing” – i.e. comparing the new intervention to best supportive care (no intervention);
    Current “best practice”
  • The treatment or practice most likely to be replaced if the new intervention is adopted

Regardless of the choice of comparator, the incremental costs and effects informing the analysis must reflect the decision problem. Comparative analysis of therapies currently in routine use should form the base case, with additional analysis exploring “do nothing” as a comparator as a minimum requirement.

The most appropriate comparator is not always immediately obvious. They may not always be alternative interventions, but can include different ways of administering the same intervention (such as different regimens or treatment sequences). The place of an intervention in a care pathway will also influence the choice of relevant comparators.