Development and Validation of an Automated Emergency Department-Based Syndromic Surveillance System for Use at a Mass Gathering Event (2020 Arctic Winter Games, Yukon Canada) During a Global Pandemic: Implications for Lower Resourced and Remote Settings

Abstract Background: Automated syndromic surveillance systems are useful tools for rapidly identifying health risks during times when routine surveillance and follow-up cannot meet the demands of the population. In Yukon, Canada, the Arctic Winter Games were scheduled in March 2020, and were expected to increase the local population beyond the capacity of local public health surveillance. An emergency department-based automated syndromic surveillance system was therefore developed and validated using local hospitalization records for use during the event. Methods: Syndromes of interest were identified in consultation with the local public health authorities. For each syndrome, case definitions were developed using published resources and expert elicitation. Natural language processing algorithms were then written to detect syndromic cases from three different fields (triage notes; chief complaint; discharge diagnosis) using Yukon emergency department case data containing information from 19,082 visits over the period of October 1, 2018 to April 30, 2019. The automatic identification of cases was then manually validated by two raters and results were used to calculate positive predicted values for each syndrome and identify improvements to the detection algorithms. Results: A total of six syndromes were originally identified for the syndromic surveillance system (e.g., Gastrointestinal, Influenza-like-Illness, Mumps, Neurological Infections, Rash, Respiratory), with an additional syndrome added to assist in detecting potential cases of COVID-19. The positive predictive value for the automated detection of each syndrome ranged from 48.8%-89.5% to 62.5%-94.1% after implementing improvements identified during validation. As expected, no records were flagged for COVID-19 from our validation dataset. However, the system was rapidly adapted into an additional surveillance tool for use in the COVID-19 pandemic. Conclusions: Validation is an important step for measuring the accuracy of syndromic surveillance, and ensuring it performs adequately in a local context. Ultimately, the 2020 Arctic Winter Games were cancelled due to the risks associated with mass gatherings during the global pandemic of COVID-19 and could not therefore be tested under a mass gathering scenario. However, the results from our validation study suggest that our surveillance system may be useful for future mass gathering events and proved a timely development for integration into Yukon’s COVID-19 surveillance infrastructure.