Low implementation of cost-effective health technologies results in inefficient use of resources in a health system. Despite this, estimates of implementation or diffusion are not routine components of analyses performed within health technology assessments (HTA), potentially due to a lack of a) methods to obtain diffusion estimates and b) understanding of the impact of diffusion estimates on health economic outcomes. This thesis contributes a) a method to estimate health technology diffusion prior to HTA and b) a modelling framework that assesses the potential impact of diffusion estimates on cost-effectiveness and expected value of information and implementation (EVII) analysis using modelling, qualitative and elicitation methods. These were illustrated in a preterm birth (PTB) screening case study.
The modelling framework included extensions to an existing EVII model to make it dynamic and allow research to affect implementation; and the development of a dynamic cost-effectiveness analysis (DCEA) model that reflects price changes precipitated by diffusion and hence, the reimbursement decision. Drivers of diffusion were identified for the case study technology, aiding the design of implementation strategies. The developed method for predicting diffusion requires transformation of elicited expert beliefs to inform an existing diffusion model. Application in the PTB screening model showed that the dynamic EVII method can 1.) help more accurately assess the losses the health care payer incurs when there is decision uncertainty and low implementation and 2.) provide more realistic assessments of implementation strategies and evidence generation schemes. The applied DCEA model showed that changes in price triggered by technology diffusion significantly affect cost-effectiveness results. The method for predicting health technology diffusion and the EVII and DCEA frameworks are foreseen to be relevant in the context of HTAs of medical devices, diagnostics and drugs; particularly when there is low implementation or there is potential for future price changes conditional on diffusion
