Method: Visualization methods and their applications in healthcare, engineering, and operations research were sought from a wide variety of sources, including literature databases (e.g. PubMed) and webpages of simulation conference (e.g. WSC), academic societies and further publications (e.g. FIPS PUBS). The literature review focused on model conceptualization and programming, and presentation of the results.
Result: For depicting the conceptual model, visualization methods such as event graphs, activity diagrams, IDEF (Integration DEFinition) diagrams, process-flow diagrams, or petri nets were used in engineering and operations research. For example, event-graph diagrams are well suited for simple problems. However, interactions between individuals (e.g. queues), resources and decisions are not made explicit. Therefore, more elaborated techniques such as IDEF diagrams or process-flow diagrams are applied. The recently published ISPOR-SMDM Modeling Good Research Practice guidelines recommend flow diagrams or state charts to represent the key elements of a model, including the possible pathways, and the presence of queues and decision points. Flow diagrams seem to be a good form of visualization that is also applied to support programming within VPLs and software. However, for illustrating concepts such as the natural history of a disease in a decision-analytic model, a how-to guidance would be helpful. In addition, animated representation of a DES is recommended for engaging the model users and to support model debugging. Results of a DES model can be presented in commonly used formats in HTAs and cost-effectiveness studies (e.g., tables or cost-effectiveness plane).
Conclusion: There exist several visualization techniques for the three different purposes: conceptualization, programming and representation of the results. For reporting the results, standard methods used in HTA can be applied also for DES models. Flow diagrams are well suited for model conceptualization and programming purposes. Future studies are warranted for further specification and standardization of visualization methods to be used in DES studies in healthcare.