Greater New Orleans Community Substance Use Health Profile
Appendix A: Data Sources Documentation
Louisiana Early Event Detection System (LEEDS)
(Emergency Department Syndromic Surveillance)
Louisiana Early Event Detection System (LEEDS) is a web-based syndromic surveillance
system that, on a daily basis, automatically processes hospital emergency department data to
identify visits indicative of specific syndromes tracked by the Infectious Diseases Epidemiology
Section of the Louisiana Office of Public Health (OPH).
Syndromic Surveillance
Syndromic Surveillance is the collection and analysis of pre-diagnostic as well as non-clinical
disease indicators using pre-existing electronic data1, typically collected on a daily basis. The
goal of Syndromic Surveillance is to rapidly detect early warning signs of both natural and manmade disease trends or outbreaks that might impact the health of the public. Syndromic
Surveillance uses pre-diagnostic data in order to provide:
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earlier detection and awareness of outbreaks or disease trends of public health
significance;
ongoing monitoring of syndromes of public health importance;
monitoring of seasonal disease trends, such as influenza during winter months;
situational awareness during any identified cluster of cases or outbreak, during natural or
man-made emergencies, or during high-profile events; and
the potential to other track events such as hospital acquired infections, injuries and
infections during hurricanes, environmental exposures, poisonings, bioterrorism events,
exposure to toxins, and drug abuse trends.
Louisiana Early Event Detection System (LEEDS)
LEEDS tracks numerous syndromes and is used by the Infectious Diseases Epidemiology
Section of the Louisiana Office of Public Health for important public health surveillance
activities including:
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Foodborne, waterborne and other gastrointestinal illness outbreak detection and
surveillance
Influenza-like illness surveillance
Asthma surveillance
Upper and lower respiratory tract infections surveillance
Health effects due to air pollution – marsh fires, chemical disasters, etc.
Healthcare-associated infections (HAI) surveillance
Sosin DA. Biosecurity and Bioterrorism 2003; 1(4): 247-53.
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Generic outbreak detection (skin and soft tissue infections (SSTI), rashes, detection of
vaccine-preventable diseases)
Bioterrorism agents surveillance (botulism, ricin, viral hemorrhagic fevers, pneumonias,
anthrax, plague)
Zoonotic diseases surveillance
Drug and alcohol abuse surveillance
Special pathogens surveillance
Special event surveillance
Data Collection
LEEDS receives daily electronic data files from emergency departments. Specific data items
reported to LEEDS include Facility Name, Date of Visit, Time of Visit, Age, Date of Birth,
Gender, Patient's Residence Zip Code, Emergency Department Chief Complaint (text and/or ICD
code), Emergency Department Discharge Disposition, and Emergency Department Discharge
Diagnosis. To assure patient confidentiality, OPH does not ask for patient name or address.
However, because of the potential need to investigate an outbreak or cluster detected through
LEEDS, participating facilities include a unique, facility-defined patient identifier (ID) for each
record submitted so that follow-up is possible.
Eleven of the 12 hospital emergency departments in Greater New Orleans’ four parishes reported
to the LEEDS system throughout calendar 2013, representing about 95 percent of all emergency
room visits. It is expected in the future that all EDs will report to LEEDS.
Behavioral Health Indicators
Based on scanning complaint codes and text as well as discharge diagnostic codes and text, the
LEEDS system identifies visits that are alcohol, drug and or mental health-associated. These visit
counts can be monitored on a daily, weekly, monthly or annual basis. LEEDS can also be used to
monitor symptomatic side effects related to consumption of certain drugs or adulterants. Future
efforts will explore the potential for routinely identifying specific type of drugs, such as
marijuana, heroin or prescription medications. The following methodological issues are noted:
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Drug-associated ED visits may involve intentional or accidental use of medicines. For
instance, an individual may unintentionally take an overdose of a legally obtained
prescription or over-the-counter drug from medicinal purposes.
Alcohol and drug-associated ED visits represent a health care burden. Since coverage of
EDs in Greater New Orleans is exceptional, LEEDS measures the magnitude of that
burden. However, some cases may be treated in urgent care facilities outside a hospital
setting. (LEEDS plans to begin collecting data from urgent care facilities as well.)
LEEDS is useful for monitoring trends in alcohol and drug problems because, other
things being equal, an increase in alcohol or drug use or substance use disorders will
result in an increase in associated ED utilization. However, LEEDS does not measure the
full magnitude of the “problem,” only part of the acute health care component. Further,
different types of substance use may be more or less likely to result in ED visits.
Therefore, the ability to validly count visits by type of drug would very useful, although
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such counts would not in themselves measure the relative magnitude of problem across
drug types.
The impact of holidays and festivals can be tracked with daily and weekly counts.
Moveable feasts, such as Mardi Gras, may distort monthly trend estimates.
As reporting to LEEDS expands to include additional emergency departments and urgent
care facilities, counts for all syndromes will likely increase, regardless of any underlying
trend. One method to control for the increasing number of visits is to track the percentage
of total visits represented by any specific syndrome. However, by itself, this does not
provide an estimate of the magnitude of emergency and urgent health care provided for
specific syndromes over time. Another strategy is to use a fixed set of facilities reporting
throughout the period of interest. Both these methods can be confounded if facilities
beginning reporting are substantially different in services provided from facilities already
reporting or if facilities currently reporting change their service capacity, mix or mission.
Improvements or other changes to algorithms used to identify syndromes may increase
validity or reliability of syndromic surveillance, but can create historical discontinuities
for long-term trend analysis unless the revised methodologies can be replicated backward
or the old algorithms (if valid) can continue to be used for historical trends.
Based on just a single known case with specific symptoms, a syndrome can be tracked
backward and forward to identify similar cases and possible causes. While not
emphasized here, LEEDS has been used to identify and monitor the introduction of
illegal and or adulterated drugs with harmful side effects, providing situational awareness
for potential public health responses.
Contact for Further Information
Jenna Iberg Johnson, LEEDS Coordinator
Infectious Disease Epidemiology Section
1450 Poydras Street
New Orleans, LA 70112
504-568-8312
Updated: 12/23/2013
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