Is the Comparator in Your Diagnostic Cost-Effectiveness Model “Standard of Care”? Recommendations from Literature Reviews and Expert Interviews on How to Identify and Operationalise It

Objectives This research aimed to develop best-practice recommendations for identifying the “standard of care” (SoC) and integrate it when it is the comparator in diagnostic economic models (SoC comparator). Methods A multi-methods approach comprising two pragmatic literature reviews and nine expert interviews was used. Experts rated their agreement with draft recommendations based on the authors’ analysis of the reviews. These were refined iteratively to produce final recommendations. Results Fourteen best-practice recommendations are provided. Care pathway mapping (using quantitative, qualitative or mixed-methods approaches) should be used for identifying the SoC comparator. Guidelines analysis can be integrated with expert opinion to identify pathway variability and discrepancies from clinical practice. For integrating the SoC comparator into the model, recommendations around structure, input sourcing, data aggregation and reporting, input uncertainty, and model variability are presented. For example, modellers should consider that the reference standard is not synonymous with the SoC and the SoC may not be the only comparator. The comparator limitations should be discussed with clinical experts, but elicitation of its diagnostic accuracy is not recommended. Probabilistic sensitivity analysis is recommended when evaluating the overall input uncertainty, and deterministic sensitivity analysis is useful when there is high model uncertainty or SoC variability. Consensus could not be reached for some topics (e.g. the role of real-world data, model averaging and alternative model structures), but the reported discussions provide points for consideration. Conclusions To our knowledge this is the first guidance to support modellers when identifying and operationalising the SoC comparator in diagnostic cost-effectiveness models.