Christine M. Yuan, MPH¹, LaVerne H. Jones, MPH¹, Samual C. Washington, MPH¹, John O. Davies-Cole, PhD, MPH¹, and A. Chevelle Glymph, MPH². (1) Bureau of Epidemiology and Health Risk Assessment, District of Columbia Department of Health, 825 North Capitol Street, NE, Third Floor, Washington, DC 20002, 202-442-5859, cyuan@dchealth.com, (2) Bureau of Epidemiology & Health Risk Assessment, District of Columbia Department of Health, 825 North Capitol St NE, #3142, Washington, DC 20002

Introduction: This study examines the usability of a syndromic surveillance system as a method for measuring influenza and influenza-like illness (ILI) occurrence in the District of Columbia (DC) in patients that initially complain of non-specific symptoms such as fever, cough and congestion.

Methods: Daily chief complaint data were collected for over two years at eight hospital emergency departments (EDs) in DC. Two syndromes, respiratory and unspecified infection (R/UI), were used to examine annual influenza incidence. Case information for R/UI was also collected for one month to characterize patients with influenza or ILI complaints. Summary frequencies and Chi-square tests were used to analyze patterns in R/UI syndromes.

Results: Seasonal trends consistent with influenza occurrence were observed; nonetheless, the 2003-04 data showed an earlier increase in R/UI complaints. Specific chief complaints of influenza and ILI symptoms made up 52% of all R/UI complaints. Patients were not seriously ill, however, since 74% of R/UI patients with specific influenza or ILI complaints were discharged. Temporal analysis showed that R/UI complaints varied by weekday and time-of-day intervals. Chi-square tests of association demonstrated statistically significant associations between R/UI occurrence and hospital, weekday, ED admittance time and age (á=0.05).

Conclusions: Syndromic surveillance for R/UI complaints in hospital EDs showed consistent seasonal patterns of influenza in the District. The analyses also produced a preliminary characterization of hospital ED patient syndromes. Syndromic surveillance along with traditional surveillance methods can improve influenza monitoring, thus allowing for adequate identification of illness severity, targeted vaccine distribution and hospital surge capacity preparedness.

Learning Objectives: