Emergency department patient flow simulations using spreadsheets.

INTRODUCTION: Patient flow computer simulations allow Emergency Department stakeholders to assess operational interventions, develop utilization and performance measures, and produce estimates for budgeting or planning purposes. Key challenges of traditional discrete-event computer simulation software are their inherent complexity for modeling, coding, or analyzing output and their significant costs and training. We propose a simulation platform that runs in spreadsheets. Because of their low cost, popularity and powerful functionality and performance, spreadsheets also allow for the development and management of simulations that efficiently output results that are just as reliable as those from traditional software.

METHODS: A spreadsheet simulation is developed by modeling one row as one simulated minute (more than 20,000 rows for a 2-week period). Uncertainty in arrivals, patient type, routing, and treatment times is modeled using the "rand()" function to simulate the state of the Emergency Department at a given point in time. The patient is tracked with embedded "if()" functions and summary statistics are obtained through range functions. We use an equivalence test to determine whether the resulting average length-of-stay figures are the same as those of a traditional simulation platform.

RESULTS: We find little significant difference in average length-of-stay figures between both models.

CONCLUSIONS: Spreadsheet simulations are as effective as traditional simulations but easier to use, understand, and implement. Spreadsheet software is widely available, at a fraction of the cost of discrete-event simulation software. Coding spreadsheet simulations may be more challenging as it requires a different and more novel expertise than traditional computer programming. However, spreadsheets can be organized to reference existing datasets, thus minimizing the burden of copying and likelihood of transcription errors and information leakage. Output analysis can also be customized with user-specific performance statistics and charts.