Methods of extrapolating RCT evidence for economic evaluation

Treatment costs and benefits have to estimated when they are unknown beyond a certain time period, and the appropriate time the costs or benefits last is judged by NICE to be longer. This may add uncertainty to NICE s decison making process about whether or not the treatment should be funded, as there are usually various ways of obtaining these estimates. The research project will review and compare the different approaches and recommend the best ways of undertaking the estimation for different situations.

Extrapolation of evidence over time is common in work which informs the NICE decision-making process on cost-effectiveness of health technologies. Although a variety of methods and approaches to extrapolation are used, little research has been conducted into the effect of this methodology on the decision process. This research will review the current methodology for extrapolation used in health economic modelling and develop a taxonomy of methods and approaches. The resulting categories will be critically reviewed using a set of structural uncertainty criteria developed for the purpose. The results will be illustrated using case-studies which will be selected for the particular analyses that need to be demonstrated. The results of this research will be reported and synthesised for dissemination in typical scientific forums.