To provide guidance on when to ask for specific types of economic evidence alongside other information that is being gathered in a systematic review of a medical intervention, we obtained input from members of the interdisciplinary project team and outside experts (including health economists and those having experience with systematic reviews in different countries). The discussion began with an attempt to determine how widely we wanted to define the term “economic evidence.” After deciding that our operational definition of economic evidence was wider than simply “cost-effectiveness” or even “economic evaluation,” we began by defining stakeholders and decision situations. As we progressed, it became clear that answers to the questions we were posing would best be structured pragmatically and in touch with the real life settings as answers to a series of questions that are raised in the systematic review process. The questions addressed the appropriate occasions, places, people, and methods for gathering economic evidence alongside other evidence with the same level of rigor as in a systematic review of evidence. The elements of economic evidence that are the most important to request depend on the stakeholders involved and the decisionmaking context.

A schematic diagram is shown in Figure 1 that conveys the different concepts that are used to motivate the appropriate collection of economic data alongside systematic reviews. The conceptual model provides a short heading for each of the five questions that were the focus of consideration after the model was developed. Extended versions of the questions and further justification for each question are provided below:

Figure 1

Concepts motivating the collection of economic evaluation data alongside systematic reviews.

• Why are stakeholders interested in economic evaluation data? This is the most logical starting point for discussion. Without a clear sense of the need for reviews that include economic data, the remainder of the discussion is somewhat superfluous.
• When should economic evaluation data be requested in a systematic review? Having identified the reason for interest, the next logical step is to identify the particular situations in which reviews with economic data are useful.
• Who is interested in economic evaluation data? To a degree, this is framed by the why and when questions, but it is important to clearly identify stakeholders who would be interested in the questions.
• What economic evidence is of interest? Given the large number of different types of economic evidence, it is critical to identify what types of data are useful, having established the reasons for interest, situations in which stakeholders are interested, and identity of those stakeholders.
• How should the economic evaluation be conducted? Specifying the method to be used is extremely important, given the range of options for analysis, the range of recommendations about analysis, and the constraints on resources, even after deciding on the importance of a specific type of evidence.

Prior to answering the questions, we provide definitions for several terms (Table 1). Economic evaluation involves an entire logical process and set of analytic steps that involve economic and epidemiological data. Our assumption is that those planning reviews will, in some cases, want to review the original economic data, and in other cases want to review the results of previous economic evaluations. We provide structure for thinking about both situations.

Table 1

Definitions.