HEE: Developing a reference protocol for expert elicitation in health care decision making

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Where the budget for health care is limited, difficult decisions about the use of treatments are made by decision makers. They usually consider the benefits of each alternative treatment and select the one that is expected to maximise health. When the budget is limited, money spent on a new treatment will mean other patients may not have access to the same level of health care. A decision maker needs to weigh the health gains with the losses (cost-effectiveness). To establish cost-effectiveness, decisions are usually based on a mathematical model of the disease of interest and any treatments given. Inputs to a model, for example risk of a heart attack, are required. Due to uncertainty in the evidence, the cost-effectiveness of an intervention is often not known with certainty. However, it is important that the uncertainty in cost-effectiveness estimates is reflected in any analysis conducted. If not, any decisions can be potentially misleading. In situations where information is unavailable, the experience of experts is essential. The process by which the beliefs of experts can be formally collected and recorded is "expert elicitation". Expert elicitation has been used in many areas including volcanology and weather forecasts. A number of alternative protocols (guides to good practice) are available for the design, conduct and use of expert elicitation, but it is not clear if any of these can appropriately be used to inform decisions using cost-effectiveness evidence. The overall aim of this project is to establish a reference protocol for the elicitation of experts' judgements to inform health care decision making. To do this we plan a series of work packages:WP1 Appraisal of existing protocols for eliciting distributions We will critically review available guidance for elicitation; this will include published and unpublished literature. The principles of each method will be appraised in light of a set of requirements for health care decision making. Where the review identifies gaps in knowledge, targeted searches on the alternative methods proposed will allow advantages and disadvantages of each choice to be identified and any potential constraints to their application for cost-effectiveness analyses to be established. WP2 Eliciting distributions to represent parameter uncertaintyIn order to consider uncertainty in the health care decision making process, judgements elicited need to reflect the imperfect knowledge experts have. Within WP1 we will consider alternative methods to avoid experts expressing variability. In addition, there are alternative approaches to elicit judgements (group consensus and individual expert approaches) and these differ in terms of how well uncertainty is represented. To inform the choice of approach to elicitation we will conduct an experiment. WP3 Understanding and appropriately characterising between-expert variationIt is important to include inputs from a range of experts in generating estimates of cost-effectiveness. These must be combined and there are alternative methods to do this: consensus and individual methods. There has been comparison of methods; however, results do not clearly support one approach over another and it is unclear which method best represents both within expert uncertainty and across expert variability. Within this work-package, we will conduct an experiment to explore the ability of consensus methods to generate expressions of uncertainty, particularly where between-expert variation is also important. The experiment will also allow us to explore different methods of pooling individual judgements. EVALUATION: To demonstrate the usefulness of the protocol developed in WPs 1-3, we will conduct an elicitation exercise using the protocol developed to inform a decision making process in real time. York is an Assessment Group for NICEs technology and diagnostics assessment processes. We will conduct an elicitation exercise to inform a current decision.