Using Syndromic Surveillance to Track Pollen Related Allergies Real-time

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Objective: Large parts of the country currently have inadequate monitoring of ambient pollen concentrations. This analysis investigates the association between Emergency Department (ED) syndromic data and pollen measurements to track pollen-related allergies. Methods: Daily pollen measurements were obtained from the Atlanta Asthma and Allergy Clinic monitor on the broad pollen taxa of tree and specifically for Oak species from 2017-2018. The start and end of the tree and oak pollen were separately determined based on the days when 1% and 95% of the cumulative pollen load each year were recorded. A syndrome definition was developed to specifically identify ‘allergy’-related cases using information contained in chief complaints in the emergency care setting, while avoiding allergies unrelated to pollen exposure (e.g. those associated with food or other exposures). Using the syndrome definition, a daily ratio of allergy-related ED visits to total ED visits was computed for each of the Georgia health districts. For each year, both the log-transformed pollen values and the ED visit ratios were normalized to conform to a specified range that yielded easier inter-annual comparison. Pearson correlation analysis was conducted to estimate the association between the daily pollen measurement and the daily allergy visit ratio for each of the districts. Results: Correlation coefficients using the daily tree pollen data and syndromic ED visits ranged from 0.41 to 0.67 in health districts close to the pollen monitoring station. Similar results were obtained when only Oak pollen was considered. As distance from the station increased, the strength of the correlation declined. For sensitivity analysis, correlations using pollen measurements from the same day and average over 3 days preceding the health outcome were robust. Conclusion: Robust association between the daily variations in ED syndromic data with the pollen measurements supports the application of the syndromic system to track pollen-related health outcomes.