Methods for eliciting expert opinion to inform health technology assessment

Health technology is defined to be “any method used by those working in health services to promote health, prevent and treat disease, and improve rehabilitation and long-term care”. A key function in public health policy making is the assessment of the potential efficacy and cost-effectiveness of new health technologies. The general term used for this type of assessment is health technology assessment (HTA). When assessing new (or even existing) technologies, there are often gaps in the evidence base to help judge the efficacy and cost-effectiveness of one technology over another. In the assessment of future events or unknown outcomes, elicited opinions are often all a decision maker has for an evidence base. Coupled with this, there could be limited prospect of future data collection due to costs or physical feasibility. Many academic publications have attempted to set out principles for HTA. The core principles include the transparency with regards to evidence sources, reproducibility of evidence, the use of analytical techniques that are methodologically sound and a comprehensive appreciation of uncertainty. Although take up of these principles is not uniform in HTA, many of the principles highlighted here should be noted when using expert judgements. In the context of uncertainty modelling, elicitation is the process of translating someone’s judgements about some uncertain quantities into something useful for a model. This will typically be a probability distribution. Expert elicitation can help us to take stock of the uncertainty about quantities of interest without the cost of data collection. We will be referring to experts throughout as people that have relevant knowledge about an HTA. These experts will have knowledge about the quantity of interest, and their opinion is of interest to the decision maker who wishes to use the HTA. Experts could be health or social care professionals, academics, patients or lay people. The wide coverage here matches with the aims of organisations such as the National Institute for Health and Care Excellence (NICE) to take into account the view of stakeholders and the wider public in HTA. The value of taking this approach is backed up by research on the importance of using lay knowledge in public health research due to the presence of extensive personal experiences. Popay and Williams (1996) argue that both lay people and relevant professionals “have a contribution to make to understanding [of health and illness]” and that there is real merit in eliciting judgements about future health under different scenarios. Of course, the same elicitation methods will not work for every expert and consideration of the expert’s abilities should always be taken into account when designing and running elicitation exercises. †School of Mathematics, University of Leeds, Leeds, UK. [email protected]