Setting priorities for the evaluation of health interventions: when theory does not meet practice.

Priority setting is a key component of the process of evaluating health interventions. This has traditionally been an informal process led by power and influence, but a number of explicit criteria and systematic models have been developed since the late 1980s. This paper presents a review and appraisal of these conceptual models and examines how they have influenced the practice of priority setting in the United States and Europe. The main conclusion is that a significant gap exists between theory and practice. Most models have been developed for the purpose of maximising health gains through an efficient allocation of resources. However, they present at least three important limitations that need to be removed if formal models are to play a more substantial role in decision making: they tend to prioritize interventions for evaluation, rather than evaluations themselves; they fail to address priority setting in a research portfolio perspective; and they fail to adopt an incremental perspective. Existing prioritization models are not suitable for supporting cost-containment or distributional objectives.