Table 1 The two basic study designs of economic evaluations

Trial-based evaluations

Resource use and health-related quality of life data are recorded for all participants over the duration of a clinical trial;

Cost-effectiveness of the treatment relative to control is estimated in the specific context of the trial in which the economic evaluation is nested

Model-based evaluations

Data from multiple sources, such as randomised controlled trials, observational studies, epidemiological data, and administrative records, are combined;

Mathematical models are used to estimate costs, effects, and cost-effectiveness of hypothetical (modelled) scenarios;

Useful when no single trial has collected all of the required data, when results from one context are to be applied in a different setting or population, or to evaluate more complex scenarios or long-term outcomes beyond the feasible scope of a randomised trial