Use of disease-specific reference models in economic evaluations: NICE position statement

Appendix: Anticipated benefits and challenges of a standardised approach to modelling methods

Disease-specific reference models have emerged in NICE products on several occasions over the years. This includes:

However, they have not been adopted formally by NICE or applied across all NICE products.

For some diseases, multiple NICE STAs and other guidance exist that cover the same parts of a clinical pathway (the same 'decision space'). This can lead to inconsistencies in economic model inputs and assumptions since companies, EAGs and NICE developers build their own models. Despite a rigorous quality assurance process, these inconsistencies may affect committee decisions and can result in inconsistencies between different pieces of guidance within a condition.

Disease-specific reference models or reference case extensions may enable more robust decisions to be made when recommending technologies by encouraging consistent assumptions and approaches to modelling across NICE's guidance products (Haji Ali Afzali and Karnon 2011; Haji Ali Afzali, Karnon, Merlin et al. 2012). More consistent modelling approaches across guidance products will help bring our different types of guidance together so that users can easily find the recommendations they need.

Where there are multiple models in the same decision space, the same assumptions and parameters might be discussed separately for each model. This repetitive scrutiny of different models by EAG staff and committees creates inefficiencies in the evaluation process (Wang, Pouwels, Ramaekers et al. 2024). A standardised approach may allow for a quicker decision-making process and better use of time spent by committees, EAGs and NICE in evaluating, developing and validating new economic models. Committee meeting discussions could focus on building consensus around new key issues rather than revisiting matters that have already been addressed in previous discussions.

Using disease-specific reference models can also promote transparent decision making through sharable models. A standardised approach to modelling a disease also has advantages for companies, such as:

The development and maintenance of reference models need adequate resourcing to ensure their continual robustness and prevent them from becoming out of date (Sampson, Arnold, Bryan et al. 2019, Haji Ali Afzali, Karnon, Merlin et al. 2012). Their development and maintenance can be supported by innovation in methodology, such as through AI-facilitated approaches for updating or adapting existing models, or the use of real-world data to ensure that the model outputs reflect real-world practice in England (Reason, Rawlinson, Langham et al. 2024; Fleurence, Bian, Wang et al. 2025).

Reference models require academic credibility and rigour to be suitable for decision making. Models will undergo independent critical appraisal and consultation before they are used for decision making. Involvement of patients and clinicians will ensure that any model assumptions reflect care pathways and current practice, and that models capture what matters most to the people who will be affected by decisions for new medicines.

Disease-specific reference case extensions can potentially provide many of the benefits of fully implemented reference models. They can be used for the fair and consistent:

ISBN: 978-1-4731-7230-2