2014.ISDS.Abstracts.Final.pdf


ISDS Annual Conference Proceedings 2014. This is an Open Access article distributed under the terms of the Creative Commons Attribution-
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ISDS 2014 Conference Abstracts

Assessing the Potential Impact of the BioSense 24-hour 
Rule Using NC DETECT ED Data

Amy Ising*1, Clifton Barnett1, Dennis Falls1, Anna E. Waller1, John Wallace2 and Lana 
Deyneka2

1Emergency Medicine, UNC Chapel Hill, Chapel Hill, NC, USA; 2North Carolina Division of Public Health, NC DHHS, Raleigh, NC, 
USA

Objective
NC DETECT emergency department (ED) data were analyzed 

to assess the impact of applying the BioSense “24-hour rule” that 
combines ED visits into a single visit if the patient ID and facility ID 
are the same and the earliest recorded dates occur within the same 
24-hour time frame. [1]

Introduction
Per a frequently asked questions document on the ISDS website 

[1], approximately two thirds of HL7 records received in BioSense 
do not provide a Visit ID. As a result, BioSense data processing 
rules use the patient ID, facility ID and earliest date in the record to 
identify a unique visit. If the earliest dates in records with the same 
patient ID and facility ID occur within the same 24-hour time frame, 
those two visits are combined into one visit and the earliest date will 
be stored. The ED data sent by hospitals to NC DETECT include 
unique visit IDs and these are used to identify unique visits in NC 
DETECT. These data are also sent twice daily to BioSense. In order 
to assess the potential differences between the NC DETECT ED data 
in NC DETECT and the NC DETECT ED data in BioSense, an initial 
analysis of the 24-hour rule was performed.

Methods
4,822,347 unique ED visits from 2013 NC DETECT data were 

included in this analysis. The 24-hour rule was applied to these visits; 
if ED visit records met the 24-hour rule inclusion criteria, the data 
from only the first ED visit was kept. Counts were compared to the 
data based on unique Visit ID to the data based on the 24-hour rule by 
ED disposition, age group, syndrome, payor source, transport mode, 
county of residence and patient sex. The percentage of ED visits 
“lost” to the 24-hour rule was calculated.

Results
After applying the 24-hour rule, the 4,822,437 ED visits in 2013 

were reduced to 4,740,250, a 1.7% reduction in ED visits. Table 1 
shows the lowest and highest % loss of ED visits by data element.

Conclusions
Combining ED visits by the same patient that occur at the same 

facility within 24 hours reduces the overall ED visit count in NC by 
approximately 1.7%. The percentage of ED visits lost is higher for 
certain types of visits, e.g. behavioral health, healthcare utilization, 
GI illness and varies significantly across counties in NC. Additional 
research and documentation are needed to determine if this initial 
analysis is an accurate understanding of the BioSense 24-hour rule, 
and the potential impact this has on timely surveillance for select 
indicators.

Table 1: Percentage of ED Visits Lost After Applying the 24-hour rule, by 
Select Data Elements

Keywords
data quality; BioSense; data processing; emergency department data

Acknowledgments

NC DETECT is funded with federal funds by the North Carolina 
Division of Public Health, Public Health Emergency Preparedness Grant 
(PHEP), and managed through a collaboration between NC DPH and the 
UNC Department of Emergency Medicine Carolina Center for Health 
Informatics.

References

1. BioSense v2.0 Webinar: Data Processing [Internet]. Boston: ISDS
[cited 2014 Sept 9]. Available from http://www.syndromic.org/
resources/isds-webinars/upcoming-recent/742-biosense2-webinar-
data-processing.

*Amy Ising

E-mail: ising@ad.unc.edu    

Online Journal of Public Health Informatics * ISSN 1947-2579 * http://ojphi.org * (1):e84, 201