Economic evaluation alongside randomised controlled trials: design, conduct, analysis, and reporting
BMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d1548 (Published 07 April 2011) Cite this as: BMJ 2011;342:d1548
- Stavros Petrou, professor1,
- Alastair Gray, professor of health economics2
- 1Warwick Clinical Trials Unit, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
- 2Health Economics Research Centre, Department of Public Health, University of Oxford, Oxford, UK
- Correspondence to: S Petrou S.Petrou{at}warwick.ac.uk
- Accepted 8 February 2011
Economic evaluation involves the comparative analysis of the costs and consequences of alternative programmes or interventions.1 It has increasingly been used to inform decision making about healthcare in the United Kingdom and other industrialised nations.2 3 4 5 Randomised controlled trials are commonly used as a vehicle for economic evaluations. Indeed, many funders, such as the UK National Institute for Health Research Health Technology Assessment Programme, routinely request that assessments of cost effectiveness are incorporated in the design of randomised trials. This article outlines some of the key issues concerning the design, conduct, analysis, and reporting of economic evaluations based on trials with individual patient data. Economic evaluations that synthesise data from disparate sources using decision analytical models (typically using summary rather than individual patient data) are discussed in an accompanying article.6
What are the objectives of economic evaluation?
Economic evaluations are typically concerned with two quantities: the additional cost of a new treatment compared with the existing alternative and the additional health benefits. If all the costs and outcomes relevant to this comparison can be measured, they can then be averaged across all patients in the treatment (t) or the control (c) group to obtain mean cost C and mean effect E for each group. It then becomes possible to calculate a third quantity: the cost effectiveness of the new treatment compared with the alternative. The incremental cost effectiveness ratio (ICER) will simply be the difference in costs divided by the difference in effects: ICER=Ct−Cc/Et−Ec=ΔC/ΔE.
This can be shown neatly on the cost effectiveness plane (fig⇓).7 In the south …