Biology Reference
In-Depth Information
16.2 What Is Syndromic Surveillance?
Syndromic surveillance (see Introduction chapter) refers to data from any
nontraditional source that are delivered repeatedly over a timely interval
(usually daily) and analyzed to identify and track emerging trends in inju-
ries, accidents, or diseases that traditional surveillance could potentially
miss. The term “syndromic” refers to the monitoring of patterns or collec-
tions of symptoms or events that taken together may indicate an underlying
health condition. In public health, surveillance refers to the monitoring or
tracking of disease conditions.
Traditional health surveillance systems typically focus on identifying and
confirming diagnoses of specific disorders. Traditional surveillance data
are generally collected through direct physician reporting, diagnostic lab
reporting, and probabilistic surveys. Although not always the case, tradi-
tional surveillance systems usually emphasize accuracy, completeness of
reporting, and the ability to infer results to the population of interest over
timeliness of reporting. For example, a traditional influenza surveillance
program might test all patients with influenza-like illnesses (ILI) who seek
health care at specific sentinel sites for flu and report those cases that are
diagnostically confirmed.
In contrast, syndromic surveillance is far more concerned with the
timely detection of events and the ability to identify and monitor trends.
Syndromic surveillance systems generally assume that certain conditions
will result in behaviors that produce records and then compare and eval-
uate those records to detect disease trends in terms of deviations from
historical norms. A typical syndromic surveillance system for influenza
might evaluate all chief complaint records from emergency departments
across a state and look for spikes in complaints of ILI itself, whether those
patients test positive for influenza or not. The underlying assumption of
syndromic surveillance is that detecting a spike in ILI provides nearly as
much information as detecting a spike in actual diagnoses of influenza,
but that the information can be obtained more quickly and potentially at
a lower cost.
Since the mid-1990s, states, counties, and municipalities have imple-
mented a number of types of syndromic surveillance systems. Most com-
monly, areas collect emergency department (ED) chief complaint data.
These ED systems involve daily reporting of the reasons patients seek
emergency services to a centralized public health department located in
the city, the county, or the state (e.g., the International Society for Disease
Surveillance (ISDS) Distribute Project (ED ILI Syndromic Aggregation)
http://isdsdistribute.org). Other types of syndromic surveillance systems
track over-the-counter pharmacy sales data (usually in cooperation with a
major credit card company), hospital, or public health clinic admissions, or
electronic diagnostic lab records, or obtain data from emergency services or
