ISDS Annual Conference Proceedings 2017. This is an Open Access article distributed under the terms of the Creative Commons Attribution-
Noncommercial 3.0 Unported License (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution,  
and reproduction in any medium, provided the original work is properly cited.

ISDS 2016 Conference Abstracts

Relationship Between Baseline Influenza-like Illness 
Rates And Healthcare Settings
Dino P. Rumoro1, Shital C. Shah*1, Gillian S. Gibbs1, Marilyn M. Hallock1, 
Gordon M. Trenholme1 and Michael J. Waddell2
1Emergency Medicine, Rush University Medical Center, Chicago, IL, USA; 2Pangaea Information Technologies, Chicago, IL, USA

Objective
To examine the baseline influenza-like illness (ILI) rates in the 

emergency departments (ED) of a large academic medical center 
(AMC), community hospital (CH), and neighboring adult and 
pediatric primary care clinics.

Introduction
The primary goal of syndromic surveillance is early recognition 

of disease trends, in order to identify and control infectious disease 
outbreaks, such as influenza. For surveillance of influenza-like illness 
(ILI), public health departments receive data from multiple sources 
with varying degrees of patient acuity, including outpatient clinics 
and emergency departments. However, the lack of standardization of 
these data sources may lead to varying baseline levels of ILI activity 
within a local area.

Methods
Geographic Utilization of Artificial Intelligence in Real-Time 

for Disease Identification and Alert Notification (GUARDIAN) – a 
syndromic surveillance program – was used to automate ILI detection 
using free text chief complaint/reason for visit fields and vital signs 
for a large AMC - ED, CH - ED, and neighboring outpatient clinics 
during the summer (June 15, 2016 to August 18, 2016) in order to 
create a baseline. The GUARDIAN system defined ILI as fever 
(temperature ≥ 100°F) and cough and/or sore throat. Descriptive 
analysis of the observed ILI rates along with bivariate ANOVA with 
post hoc Bonferroni and t-test were utilized to examine the difference 
within the settings.

Results
The average ILI rate for EDs is higher than the clinics by at least 

0.39%. The CH- ED had 4.23% baseline ILI rate as compared to 
1.35% for AMC-ED. While the AMC – Clinics have 0.96% baseline 
ILI rate as compared to 0.25% for CH – Clinics. The CH- ED and 
AMC – Clinics represented higher variations. Based on bivariate test, 
CH – ED was significantly different than AMC – ED, AMC - Clinics, 
and CH – Clinics (F= 10.58, df = 1238, p<0.05). For the AMC – 
Clinics, the average ILI rate for clinics providing services to adult 
patients was 0.66% (SD: 4.5%) as compared to 2.03% (SD: 10.81%) 
for pediatric clinics, which was not statistically significant.

Conclusions
The CH - ED has higher baseline ILI rates compared to other 

settings, as well as the CDC Region 5’s baseline (1.9% for 2015-
2016). Based on previous studies1, this is likely due to providers’ 
use of chief complaint free text fields. Thus, the CH – ED will have 
higher thresholds for widespread ILI activity. In addition, differences 
in baseline ILI rates between AMC - ED, AMC - Clinics, and CH - 
Clinics may result in different thresholds for widespread ILI activity 
(i.e., Average + 3 Standard Deviations). The CH – ED and AMC – 
Clinics had higher baseline standard deviations, indicting variations 
in underlying patient populations. In addition, pediatric clinics have 
higher baseline ILI activity but also higher variations, indicating the 
unique characteristics of pediatric patients. Thus, due to the above 

findings, there is a need to closely monitor the ILI rates at various 
healthcare sites for both timing of onset, as well as the intensity of 
ILI activity.

Table 1. Baseline influenza-like illness (ILI) rates during summer 2016

Note: AMC = Academic Medical Center and CH = Community Hospital. 
ANOVA with post hoc Bonferroni results CH - ED significantly different than 
AMC - ED, AMC Clinics, and CH - Clinics

Keywords
GUARDIAN; Influenza-like illness; Baseline ILI rates

Acknowledgments
GUARDIAN is funded by the US Department of Defense, Telemedicine 
and Advanced Technology Research Center, Award numbers 
W81XWH-09-1-0662 and W81XWH-11-1-0711.

References
1. Rumoro, D., Shah, S., Hallock, M., Gibbs, G., Trenholme, G., Waddell, 

M., & Bernstein, J. The impact of documentation style on influenza-
like illness rates in the emergency department [Abstract]. Online 
Journal of Public Health Informatics. 2016;8(1) e35.

*Shital C. Shah
E-mail: Shital_Shah@rush.edu

Online Journal of Public Health Informatics * ISSN 1947-2579 * http://ojphi.org * 9(1):e119, 2017