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 Emergency Department Syndromic Surveillance (EDSS)Background:
The need to improve the capacity
of Ontario’s public health system to prevent and respond to
outbreaks of infectious disease has been well-documented both pre- and
post-SARS, and is a key component of Operation Health Protection.
In response to this need, the Public Health Division of the Ministry
of Health and Long Term Care established and funded the Emergency
Department Syndromic Surveillance (EDSS) Steering Committee. This
Committee oversaw a 2-year pilot project, initiated
in September 2004, to implement and assess a surveillance system
monitoring emergency department visits based on the Real-time Outbreak
and Disease Surveillance (RODS) system developed at the University
of Pittsburgh. Substantial modifications were made to the RODS 3.0
system to reflect the needs of an Ontario early warning system (eg.
improved mapping and capture of admissions).
Goal:
The goals of the EDSS system were to monitor changes and trends in the incidence of endemic disease with a focus on respiratory and gastrointestinal illness and to detect new or emerging infectious disease threats.
Data Collection:
The EDSS system monitors visits to the Emergency Departments (ED) at fifty-five hospitals across Ontario. It captures data for approximately 4,000 visits and 600 admissions per day, drawing from a provincial population of over 12,000,000. Of these hospitals, eleven are in the South-East Local Health Integration Network (SE LHIN); three in the Kingston, Frontenac and Lennox & Addington (KFL&A) Public Health region, four hospitals in the Hastings and Prince Edward (HPE) Counties Health Unit catchments, three hospitals in Leeds, Grenville and Lennox (LGL) area, and one hospital in the Peterborough County-City Health Unit. These eleven sites have approximately 340,000 visits per year within a catchment area population of approximately 640,000, with the EDSS system capturing over 80% of the ED visits by this population. Information from each of these visits is collected at triage when the patient is registered in the ED at which point it is entered into the hospital’s computer system in ‘real-time’ – within minutes of speaking with the triage nurse. Data elements required by the EDSS system include the date and time of visit, patient demographics (age and sex), a geographic identifier and the patient’s chief complaint (symptoms and/or reason for visit). No personal identifiers (e.g. name, date of birth, address etc.) are included or required. Similar information is collected for hospital admissions. To see reports outlining the data collected by the EDSS system, visit the Bi-weekly Reports page of our website. Syndrome Classification,
Anomaly Detection, and Alert Investigation:
Information from each ED visit across all fifty-five sites is collected
centrally within the EDSS system where it is then classified into
syndromes (based on the patient’s chief complaint). Anomaly
detection using the RODS RLS ('recursive least squares') algorithm
and a modified EARS (Early Aberration Reporting System) cumulative
sum algorithm takes place automatically every six hours to detect
increasing numbers of visits for different syndromes, and generating
alerts to notify public health staff monitoring the EDSS system
of these increases. The EDSS system includes a secure web-based
interface that allows epidemiologists or other health professionals
to monitor the collected information. Alerts generated by the EDSS
system are immediately posted to the website and emailed to health
professionals monitoring the EDSS system. The secure web-based interface
allows the user to assess the ED visits that comprise the alert
to determine whether epidemiological links relating to the demographics,
geographic clustering or timing of the cases can be identified and
warrant further investigation by public health staff. August 2nd,
2005 marked the start of ‘go live’ for the EDSS system
such that all alerts required follow-up investigation and action
where appropriate according to defined protocols.
Evaluation: A comprehensive three-part evaluation of the EDSS project has been completed. The evaluation consisted of a process and outcome evaluation, a cost-benefit evaluation, and a technical evaluation.
Participating Hospitals
The EDSS project receives real-time emergency room data from a total of fifty-five Ontario hospitals. Together, these hospitals span six Local Health Area Networks (LHINs), which encompass eighteen Health Units.
Hospitals with EDSS Data Share Argeements Hospitals in EDSS |
