Efficacy and Effectiveness

First of all, we need to be clear about what we mean when evaluating the benefits of interventions

Efficacy

• is the benefit due to intervention under ideal conditions (eg. full compliance, stringent follow-up and patient support).

Effectiveness

• is the benefit due to intervention in real life (natural) conditions.

The objective of economic evaluation is to inform on the value of interventions in the way they would be implemented in practice and thus the effectiveness is the benefit/outcome of interest.