Expected health benefits of additional evidence: Principles, methods and applications

The purpose of this research is to illustrate: i) the principles of what assessments are required when considering the need for additional evidence and the priority of proposed research; and ii) how these assessments might be informed by quantitative analysis based on standard methods of systematic review and meta-analysis. We briefly outline the principles of what type of assessments are needed when considering research prioritization and commissioning. These are more fully examined through the integration of the principles of value of information analysis with the type of meta-analysis commonly conducted in systematic review and its application to four topics or case studies. The case studies were selected to cover a number of contexts in which these assessments are likely to be required and include: where the primary endpoint in existing studies capture key aspects of outcome; where it can be linked to other important aspects of outcome; when different ‘weights’ might be used to reflect the relevance and quality of different studies and when more than two alternative interventions need to be compared. Throughout, we distinguish the value of additional evidence and the value of implementing the findings from existing research. We also show how the value of additional evidence and the need for further research depends on the clinical difference in key aspects of outcome that would need to be demonstrated before clinical practice ‘should’ or is likely to change. We also consider whether the expected health benefits of additional evidence are sufficient to regard a particular research proposal as potentially worthwhile and whether it should it be prioritized over other research topics that could have been commissioned with the same resources. We also set out the implications of this type of analysis for research design, including whether randomised design is likely to be needed, the most appropriate scale of future research and the sequence in which different types of study might be undertaken. The report demonstrates how making best use of the results of standard meta-analysis can directly inform the questions posed in research prioritisation and commissioning. In principle, this type of analysis could become part of the routine reporting of the findings of systematic review. In addition, it is sufficiently general to be relevant across a range of different types of health care systems, whether or not formal cost effectiveness analysis is explicitly used as part of the decision making process.