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H1N1 Disease Surveillance:
The Information Architecture for
County Public Health Services
MED INF 405 – Team Project Paper
Team Members
Melody Dungee
Beena Joy
David Medina
Calvin Palmer
H1N1 Disease Surveillance
MED INF 405 – Team Paper
CONTENTS
Overview............................................................................................................................... 1
Problem ....................................................................................................................................................................................... 1
Project Objective ...................................................................................................................................................................... 2
Stakeholders ......................................................................................................................... 2
Description of Stakeholders ................................................................................................................................................ 2
Stakeholder Interests............................................................................................................................................................. 2
Business Case ........................................................................................................................ 3
Workflow .............................................................................................................................. 4
Actors............................................................................................................................................................................................ 4
People..................................................................................................................................................................................................4
System .................................................................................................................................................................................................4
Current State - Paper-based reporting ........................................................................................................................... 5
Problems ............................................................................................................................................................................................5
Future State – NEDSS-based biosurveillance system ............................................................................................... 6
Benefits...............................................................................................................................................................................................8
Workflow Scenarios ............................................................................................................................................................... 8
Laboratory alert: H1N1 test order ........................................................................................................................................8
Laboratory alert: H1N1 test results (preliminary/final) ...........................................................................................8
Web-based H1N1 Biosurveillance Document entry ................................................................................................... 11
CIS Generated Biosurveillance document ....................................................................................................................... 13
System Requirements .......................................................................................................... 15
Standards ............................................................................................................................ 16
Use of standards and specifications by systems actor ........................................................................................... 16
Description of standards and specifications .............................................................................................................. 18
Usage example of standard (HITSP/C37).................................................................................................................... 20
Example of a HITSP/C37 Message from LIMS to CPHS ............................................................................................ 20
HITSP/C37 Lab Report Document Component Specification ................................................................................ 20
HITSP/C37 Data Structure .................................................................................................................................................... 20
Information Architecture ..................................................................................................... 22
Data Sets ............................................................................................................................. 23
Data Element Constraints .................................................................................................................................................. 23
Definition of individual data elements ......................................................................................................................... 23
Demographics .............................................................................................................................................................................. 23
Clinical Data (Signs, Symptoms) ......................................................................................................................................... 23
Medical History ........................................................................................................................................................................... 24
Diagnostic Findings ................................................................................................................................................................... 24
Treatment ...................................................................................................................................................................................... 25
Epidemiology................................................................................................................................................................................ 25
Data set sources ..................................................................................................................................................................... 25
Data flow diagram ................................................................................................................................................................. 30
H1N1 Disease Surveillance
MED INF 405 – Team Paper
Overview
County Public Health Services (CPHS) is the local agency responsible for public health activities
in Sickly Falls, TX. CPHS conducts a number of public health related activities such as health
monitoring, community health education, health policy development, operation of essential
community health services, investigation of potential community health problems as well as
other public health services as directed by law. One of the most important public health
responsibilities facing CPHS is that of local disease surveillance.
In the context of public health, the intent of surveillance can be summed up in the following
phrase: “Information for Action.” This is further defined as “…ongoing systemic collection,
collation, analysis and interpretation of data and the dissemination of information to those who
need to know in order that action may be taken.”i Effective surveillance will depend upon a
robust disease surveillance and response system that will promote better coordination and
integration of the surveillance functions across the various stakeholders in the local community.
According to the World Health Organization, pandemic influenza A (H1N1) is now the
predominant flu strain circulating in most areas across the globe. The U.S. is expected to
conform to this trend, as the number of new cases seems to be expanding in the northern
hemisphere. In addition, the consequences of a potential pandemic may prove to be
staggering to the health the U. S. population. For example, according to the President’s Council
of Advisors on Science and Technology, in 2009 H1N1 may infect almost one half of the U.S.
population, requiring 1.8M hospitalizations and result in 30,000 to 90,000 deaths.ii As a
consequence, H1N1 surveillance has become a priority of Sickly Falls, TX and County Public
Health Services.
Problem
According to the Associated Press, U.S. health officials have decide not to mount a nation effort
to count cases of swine flu, instead “The Centers for Disease Control and Prevention is relying
on a patchwork system of gathering death and hospitalization numbers. Some states are
reporting lab-confirmed cases. Others report illnesses that could be the new swine flu,
seasonal flu or some other respiratory disease.”iii As a result, in order to determine the
potential spread of H1N1 infection in the local community, CPHS will need to develop a method
to monitor for a potential disease outbreak.
Currently, there is no mechanism for detecting and monitoring the spread of H1N1 disease in
the local community. CPHS has decided to address this issue by capitalizing on the fact that
most local healthcare providers and service organizations (e.g., laboratories, etc.) utilize or have
access to some sort of electronic medical record, reporting system or even access to the
Internet. To support H1N1 disease surveillance, CPHS will need to design an information
architecture that will enable the integration, and analysis, of local records and data sources.
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MED INF 405 – Team Paper
Project Objective
The overriding objective of this project is to develop an information architecture that will
integrate the data sources of healthcare providers, service providers and other stakeholders in
Sickly Falls, TX. This information will be integrated into a central data source at CPHS, which
can provide early warning of an outbreak, through alerts, and can be analyzed to provide
insights into disease vectors, high-risk populations and other information, which may be of
value to CPHS in developing public health policy.
Stakeholders
Description of Stakeholders
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State and Local Public Health Departments – are entities developed with the sole
purpose of protecting the health of state and local communities
Community Members – are key players in the well being of all defined stakeholders
Businesses – are the mainstay of any community. Any disruption in services would
directly affect the local community
Charities (homeless shelters, etc.), faith-based organizations, educational institutions,
day care, hospitality – are entities dedicated to assisting community members their
financial base is largely contributed to by community, business, and government
agencies. Any disruption with those 3 providers would cause negative financial
consequences as well workforce.
Local Hospitals/Clinics and physicians - provide services needed to care for an affected
H1N1 population
Local healthcare provider organizations – would be indirectly affected; may need to
handle overflow from hospital, clinics, or physicians
Labs and pharmacies – would be needed to diagnose H1N1 and to provide needed
medication treatment
Long-term and ancillary care – this population is one of the targeted high-risk groups for
fatalities if infected with H1N1
Local Government Organizations – would be utilized to help obtain bureaucratic
assistance if needed
Fire and Police Departments, Red Cross, Local Agencies - might be called upon to assist
in an outbreak
Stakeholder Interests
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State and Local Public Health Departments – In the event of an H1N1 outbreak, the local
and state public health departments would be the main organization utilized to obtain
vaccinations and to retrieve needed treatment information.
Community Members - may be called upon to help to fill positions of affected
stakeholders in an effort to keep the community operating as normal.
Business - an unreported H1N1 outbreak would cause financial losses to not only local
businesses but also the financial well being of the local community
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MED INF 405 – Team Paper
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Charities (homeless shelters, etc.), faith-based organizations, educational institutions,
day care, hospitality - these facilities have limited resources and any disruption in
“normal” workflow could be catastrophic to these organizations
Local Hospitals/Clinics and physicians – would treat affected patients and as such would
be one of the main stakeholders in an H1N1 outbreak.
Local healthcare provider organizations – may be called upon to handle “overflow” of
patients if the hospital has no more room.
Labs and Pharmacies – would provided services to diagnose and treat patients,
respectively
Long-term care and ancillary care – are high-risk groups that need to be notified as soon
as an outbreak is detected in an effort to keep this group safe
Local Government Organizations – would be the path needed to obtain emergency
services at a state or federal level
Fire and Police Departments, Red Cross, Local Agencies – would be used to keep
community members “under control” and to assist as needed
Business Case
The business case for developing the information architecture for an H1N1 surveillance
program is fairly straightforward and, if successful, will address the following problems:
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Monitor and reduce the spread of H1N1 disease in the local community
Determine the required data sources and the integration issues that must be addressed
by the information architecture
Enable analysis of H1N1 surveillance data
o Determine risk factors (ID high risk groups) for prediction and control
o Enable development of prevention strategies
This project can be justified from two perspectives: financial and the regulatory responsibilities
of a public health organization. From a financial perspective the issues include the following:
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Reduce cost of medical care (i.e., estimated 1.8M hospital admissions, etc.)
Effect on U.S. business
o Absenteeism - 84% of business concerned H1N1 outbreak will adversely affect
their business
o 67% of respondents replied that they would note operational problems if 50% of
workforce off for more than 2 weeksiv
As a public health agency CPHS has a number of regulatory mandated responsibilities that will
require the completion of this project in order to be completed. These responsibilities include
the following:
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Guide the development of decisions regarding the local public health response
Guide the formulation of local public health policies
Evaluate effectiveness of local public health programs for H1N1
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MED INF 405 – Team Paper
HIPAA issues should not be a major factor in the development of this information architecture
as CPHS is considered a public health authority as defined by HIPAA, 45 CFR 164.501, where a
public health authority is defined as “an agency or authority of…, a
State,…, or a political subdivision of a State…, that is responsible for public health matters as
part of its official mandate.” 45 CFR 164.512(b) allows covered entities to disclose protected
health information to public health authorities.
From a business case point of view the goals and objectives of this project are as follows:
 Identification and integration of all data sources needed for effective H1N1 surveillance
 Be able to identify potential H1N1 cases in near real-time
 Improve timeliness and accuracy of communications regarding H1N1 virus in the local
community
 Communicate potential H1N1 cases to community epidemiologists within 24 hours of
confirmed H1N1 cases
 Provide sufficient information for local authorities to develop local mitigation strategies
 Avoidance of projected H1N1 infection rates
 Based on President’s Council of Advisors on Science and Technology Report
Workflow
H1N1 surveillance activities: Cases may be reported from a variety of sources from within the
health care setting, such as clinical laboratories and private physicians. This data is then
collected, managed, transmitted, analyzed, accessed and disseminated.
Actors
People

Clinician – Any healthcare provider who has direct patient interaction in the delivery of
care including physicians, nurses and clinical supervisors. They are involved in the
evaluation of patients and the entry of source data and clinical information into the
system.
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Public Health Officials – These actors are the staff of County Public Health Services
(CPHS) who are responsible for interacting with the biosurveillance system for
indications of H1N1 infection.
System
4
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Laboratory Information System (LIMS) - A laboratory information system that supports
the testing, analysis and data management for a clinical or pathology laboratory. These
laboratories can either be independent clinical laboratories, physician office laboratories
or hospital-based laboratories.

Clinical Information Systems – Any information system (EMR, EHR or PHR), which
supports the clinical care information management needs either of hospitals, inpatient
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MED INF 405 – Team Paper
organizations, ambulatory care (e.g., community physician offices), outpatient or
emergency care organizations.
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County Public Health System – This is the regional public health authority tasked with
tracking H1N1 disease in Sickly Falls, TX.
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CPHS Biosurveillance System – This is the central data store and application used by
CPHS for entry, management and querying of the demographic and diseases data.
Based on the NEDSS system software, it provides a mechanism for web-based data
entry, electronic interchange of laboratory data, storage and maintenance of data,
query and reporting capabilities.
Current State - Paper-based reporting
Current paper-based data collection system
The current biosurveillance system is a voluntary, paper-based process where a clinician or
laboratory that has a suspected or confirmed H1N1 diagnosis completes a paper biosurveillance
form and submits it to the CPHS either by fax or by mail. Not only is this process cumbersome
and time consuming, resulting in lag-times for the reporting of potential H1N1 cases, but, it also
severely limits the speed at which any practical use can be made of the data. The current state
of biosurveillance is rife with problems.
Problems
The current biosurveillance system is burdened by many problems that will not allow the
system to be useful for H1N1 disease surveillance, where rapid recognition of H1N1 infection
coupled with near-real time analysis is the key to an effective response that may avoid an H1N1
disease outbreak.
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Data Collection – Data collection places a large burden on medical care staffs that have
responsibility for disease reporting. It is often left up to health care providers to
determine if a case meets public health surveillance case definitions and to figure out
how to fill out the wide variety of forms produced by CDC and health departments. The
other element that impedes data collection is that staff must spend significant time
tracking down patient records in response to requests for more information from the
health department. v
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MED INF 405 – Team Paper
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Data management issues – The issues around data management can also impede
effective reporting. Some of the more significant data management problems include:
o Multiple case reports - Given the number of potential information sources for a
single patient, patients may be entered into the system more than once or have
discrepant data reported in different systems.
o Data entry at the health departments – CDC has created multiple data entry
systems for local and State health department data. As a result an individual
person must be entered into multiple, disparate systems. Unfortunately, each of
the CDC systems works differently, so that using more than one of them is
onerous and time consuming.v
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Data Transmission - There are many different methods for reporting data to CPHS, the
state health department or the CDC. Examples include mailing of diskettes, or
transmitting data via dial-up modems or wide area network (WAN) or using the Internet
for reporting. All of these methods are currently in place just for reporting to CDC.
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Security - In terms of electronic encryption methods, different levels of security are
being applied. For example, in a recent inventory, over 73 different surveillance systems
developed at CDC sent or received surveillance data electronically. Only 19, however,
reported encrypting the data for transmission.v
Future State – NEDSS-based biosurveillance system
In order to meet the requirements for local surveillance of H1N1 influenza cases, and facilitate
the handling and analysis of data, CPHS will develop a local biosurveillance system modeled on
the National Electronic Disease Surveillance System (NEDSS) Base System. This system will have
a number of features intended to address and fix the previously identified problems in the
current biosurveillance system.
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Data Collection – The new system should improve data collection practices by
establishing standards to enable uniform data collection practices in the local area.
These include a minimum set of demographic data that should be collected as part of
the routine surveillance, as well as standardizing data collection forms in order to
provide a consistent method of data coding. It will also provide a standard data
architecture and electronic data interchange format that will allow computer systems to
automatically generate electronic case reports, which will be transmitted to CPHS or
forwarded on to the state health department. v

Data Management - Duplication – The NEDSS system will provide data registry
matching based on reliable record matching software components and tools, that can
be used at the local and State health department levels to detect duplicate reports
based on a person’s demographic data (e.g., name, address, date of birth, sex) and
identify discrepant data.
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Data Management – Data entry at the health department - Information is entered and
stored in a consistent and uniform way in the CPHS system, which means that it can be
easily transferred between systems thereby reducing duplicate data. Using the NEDSS-
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MED INF 405 – Team Paper
based system, with the user interface of CDC-developed surveillance systems allows a
person trained on any one system to be able to move to another without changing the
way they interact with the software.
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Data Transmission - from Local to State Health Department to CDC – A NEDSS-based
system will allow for the use of the CDC’s Health Alert Network (HAN), employing the
Internet as a backbone, to communicate surveillance data, reports, training materials,
policy documents, etc., between health departments and CDC. It will also allow for
CPHS to connect with other local health departments or other organizations critical for
preparedness and response, such as community first-responders, hospital and private
laboratories, state health departments, CDC, and other federal agencies.vi
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Secure Data Network - HAN also provides a secure method for encrypting and
transferring files from a health department to a CDC program application across the
Internet. This provides the benefits of eliminating the multiple methods of receiving
data and providing a consistent, transparent method for authenticating the data source
and its integrity.
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Easing data analysis - Data collected in different surveillance and information systems
such as laboratory based system or an immunization registry will afford better analysis
since having standardized definitions for data elements will help ensure the correct
interpretation of data elements.

Data access and dissemination – The system will provide for data access, analysis and
dissemination, primarily using data warehouses. This access will provide the following
benefits: v
o Responds to requests for information by State health departments, other Federal
and State agencies, non-profit organizations, and news media in a timely fashion.
o Strengthens local health departments and their links to critical community health
organizations to form a coordinated public health response to H1N1.
Data Access and Dissemination Through a NEDSS-based System
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MED INF 405 – Team Paper
Benefits
Implementing a NEDSS-based system will provide some key benefits, as it will enforce the use
of standards. The use of standards will assure that surveillance data is easily shared, that users
familiar with one system can easily use another, and that software can be easily shared across
programs. Standards will serve as the framework that will provide integration for collection,
management, transmission, analysis, and dissemination of data, thereby ensuring that all cases
that are in the provider’s data systems are being reported correctly to local, state and federal
agencies in a secure manner.
Workflow Scenarios
There are four workflow scenarios that will be considered in the development of the
information architecture, which are laboratory orders, laboratory results, direct data entry into
the CPHS system, and an EMR generated biosurveillance document. Although there may be
other scenarios that could be considered, it is felt that these comprise the most common ones.
A description of each scenario along with a process flow diagram should help clarify how these
scenarios will work out.
Laboratory alert: H1N1 test order
A clinical information system (CIS), which can either be an EHR or EMR, generates a laboratory
order for an H1N1 virus clinical lab test. This lab test order is then passed on to CPHS Public
Health Officials, via the local laboratory LIMS, to alert them of a potential H1N1 case.
Knowledge of H1N1 tests being ordered can be used as an early warning signal of potential
H1N1 cases.
1) Patient presents with flu-like symptoms
2) Clinician documents history and physical in CIS (data is captured as discrete elements)
and suspects H1N1 infection
3) Clinician orders H1N1 test:
a. Utilizes CIS if applicable, or
b. Utilizes laboratory supplied system
4) Lab order is automatically sent to the LIMS
a. If via CIS, then via HL7 interface
5) Laboratory LIMS recognizes lab test code for H1N1 virus test
6) Laboratory LIMS sends alert message via Hl7 interface CPHS Biosurveillance system
7) CPHS Biosurveillance system receives notification of potential H1N1 case
8) CPHS receives alert confirmation of H1N1 case
9) CPHS contacts clinician for confirmation and details of patient encounter
Laboratory alert: H1N1 test results (preliminary/final)
A positive H1N1 test result would alert CPHS of a confirmed case of H1N1 flu. Information from
a positive H1N1 test would automatically be transmitted to CPHS.
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MED INF 405 – Team Paper
1) Lab order is resulted and transmitted to CPHS via HL7 interface
2) Lab order is resulted and automatically updates the patient’s record in the CIS and alerts
clinician of lab results (in red, if positive)
3) If positive test result, HITSP/C35, HITSP/C36, HITSP/C37 message sent to CPHS
Biosurveillance system
4) CPHS receives H1N1 positive test result confirmation
5) CPHS contacts clinician for confirmation and details of patient encounter
6) Clinician is alerted either via email or telephonically and provides details to CPHS
The following diagram illustrates both of these workflows:
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MED INF 405 – Team Paper
H1N1 Biosurveillance – Laboratory Alert (Workflows 1 & 2)
Clinical Information
Clinician/Provider
System (EMR/
HER)
Laboratory
Information
Management
System
CPHS
Biosurveillance
System
County Public
Health System
Test order
processed and
transmitted to
CPHS
Receives
notification H1N1
test order
Receive
notification of
potential H1N1
case
CPHS receives
positive result
Receive H1N1
confirmation
Patient presents
with potential
symptoms
Clinician
Suspects H1N1
Infection
Yes
No
Clinician
orders H1N1 test
Yes
EMR
Entry
Clinician / provider
treats patient
Clinician
receives H1N1
test result
H1N1 Test
Processed
H1N1
test
result
Positive result
Yes
No
End
Clinician / Provider
provides details
10
Contacts clinician/
provider for
confirmation and
details
H1N1 Disease Surveillance
MED INF 405 – Team Paper
Web-based H1N1 Biosurveillance Document entry
The CPHS Biosurveillance system has a web-based entry NEDSS Base System is used to
complete a biosurveillance document with the requisite demographic and H1N1 disease data
through the NEDSS web-based portal. This situation would occur in cases where neither the
laboratory LIMS or clinician’s CIS have the capability of automatically transmitting HITSP
messages. The web-based system will transmit completed forms to a central data hub at CPHS
alerting CPHS of a confirmed case of H1N1.
1) Patient presents with flu-like symptoms
2) Clinician documents history and physical in CIS (data is captured as discrete elements)
and suspects H1N1 infection (yes)
3) Clinician orders H1N1 test:
a. Utilizes CIS if applicable, or
b. Utilizes laboratory supplied system
4) Lab order is automatically sent to the LIMS
a. If via CIS, then via HL7 interface
5) Lab order is resulted and automatically updates the patient’s record in the CIS and alerts
clinician of lab results in red, if positive.
6) Clinician gives patient diagnosis of H1N1 and enters it into the EHR (data is captured as
discrete element)
7) Clinician treats patient and documents it into the CIS (data is captured as discrete
element)
8) Clinician completes web-based NEDSS form and transmits electronically to CPHS
9) CPHS NEDSS Biosurveillance system receives electronic form of H1N1 case
10) CPHS is alerted of new H1N1 case.
11) Clinician is contacted by CPHS for validation of details
The following diagram illustrates the workflow for a biosurveillance document entry.
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MED INF 405 – Team Paper
H1N1 Biosurveillance – Web-based NEDSS Dcoument Entry
Laboratory
Information
Management
System
Clinician/Provider
CPHS
Biosurveillance
System
County Public
Health System
Receive
completed H1N1
form
CPHS alerted of new
H1N1 case
Patient presents
with potential
symptoms
Clinician
Suspects H1N1
Infection
Yes
No
Clinician
orders H1N1 test
Clinician / provider
treats patient
Clinician
receives H1N1
test result
Yes
Test order
processed and
transmitted to
H1N1 Test
Processed
H1N1
test
result
Positive result
No
Yes
End
Complete webbase NEDSS
form
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MED INF 405 – Team Paper
CIS Generated Biosurveillance document
This scenario involves the automatic generation of a biosurveillance document for H1N1
disease from the Clinical Information System (EMR, EHR). This document will transmit
completed forms to a central data hub at CPHS alerting CPHS of a confirmed case of H1N1.
1) Patient presents with flu-like symptoms
2) Clinician documents history and physical in CIS (data is captured as discrete elements)
and suspects H1N1 infection (yes)
3) Clinician orders H1N1 test:
a. Utilizes CIS if applicable, or
b. Utilizes laboratory supplied system
4) Lab order is automatically sent to the LIMS
a. If via CIS, then via HL7 interface
5) Lab order is resulted and automatically updates the patient’s record in the CIS and alerts
clinician of lab results in red, if positive.
6) Clinician gives patient diagnosis of H1N1 and enters it into the CIS (data is captured as
discrete element)
7) Clinician treats patient and documents it into the CIS (data is captured as discrete
element)
8) Administrator runs a query report based on the discrete data elements documented by
the clinician and lab results of one or all of the following:
a. “Patients with a respiratory illness with a positive test result of H1N1”
b. “Patient with a respiratory illness who expired with a negative test result of H1N1”
c. “Patients without a respiratory illness with a positive test result of H1N1”
9) Report is exported from EHR and electronically sent to CPHS NEDSS Biosurveillance
system as discrete data
10) CPHS is alerted of H1N1 case
11) CPHS contacts clinician for confirmation and details of patient encounter
12) Clinician is alerted either via email or telephonically and provides details to CPHS
The following diagram illustrates the workflow of an EMR-generated biosurveillance document.
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MED INF 405 – Team Paper
H1N1 Biosurveillance – CIS Alert (Workflow #4))
Clinical Information
Clinician/Provider
System (EMR/
EHR)
Laboratory
Information
Management
System
CPHS
Biosurveillance
System
County Public
Health System
CPHS receives
EMR Alert
Message
Receive H1N1
message via alert
or query
Patient presents
with potential
symptoms
Clinician
Suspects H1N1
Infection
Yes
No
Clinician
orders H1N1 test
Yes
Treats patient and
makes data entry
EMR
Entry
Yes
H1N1 Test
Processed
H1N1
test
result
Positive test
result / H1N1
diagnosis
Positive H1N1
diagnosis
No
Yes
No
Clinician
Alerted
EMR populates
H1N1 message
with available data
End
EMR sends H1N1
alert message
Clinician / Provider
provides details
14
Yes
Contacts clinician/
provider for
confirmation and
details
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MED INF 405 – Team Paper
System Requirements
The functional requirements, listed by system actor, are intended the functions required by
each actor in order to develop an H1N1 biosurveillance system for CPHS. The goal is to transmit
essential ambulatory care and emergency department visit, utilization, and lab result data from
electronically enabled health care delivery and public health systems in standardized and
anonymized format to authorized public health agencies within 24 hours.
Laboratory Information Management System (LIMS) requirements:
1) The system uses HL7
2) The system electronically tracks patient’s laboratory orders
3) The system electronically receives laboratory orders
4) The system generates laboratory results
5) The system electronically transmits laboratory results to EHR and CPHS
6) The system electronically sends alerts when results generated to EHR and CPHS
7) The system must support HITSP/C35, HITSP/C36 and HITSP/C37 message formats
8) The system generates lab reports
9) The lab reports can be exported into any format
10) The lab reports can be transmitted electronically
Clinical Information System (EHR/EMR) requirements:
1) CIS electronically places lab orders
2) CIS electronically receives lab results
3) CIS electronically receives lab alerts
4) CIS displays lab alerts to providers
5) CIS displays abnormal lab alerts in red to provider
6) CIS electronically tracks lab results by patient
7) CIS generates lab reports by patient to providers
8) CIS generates lab reports by patient/diagnosis/lab result to providers
9) CIS electronically receives instructions from CPHS to activate certain procedures that
include laboratory testing.
10) CIS electronically receives health alerts regarding a detected public‘s health threat
event.
11) CIS supports electronic reporting of individual patient data to CPHS, using HITSP/C39
message format.
12) CIS informs provider clinical decision-support by receiving the following information
from the CHPS bio-surveillance system:
 Aggregated data on the health status of the community
 Notifications on a suspicious event
 Instructions to activate certain procedures related to the detection of the public‘s
health threat event as determined by the public health response protocols
CPHS Biosurveillance System requirements:
1) The bio-surveillance system electronically receives individual patient data from clinical
settings (ambulatory settings and hospital emergency departments) EHRs. This includes
data on symptoms, diagnosis, medication prescriptions, etc.
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2) The bio-surveillance system supports event detection algorithms
3) The bio-surveillance system analyzes individual patient data across providers to
establish pattern of suspected public’s health threat event as needed.
4) The bio-surveillance system provides electronic access for providers to the daily
community health status assessments
5) The bio-surveillance system electronically notifies providers regarding the suspected
pattern as needed.
6) The bio-surveillance system electronically send instructions to providers to activate
specific procedures to help determine the nature of the suspected pattern, e.g., order
specific lab tests, ask certain questions during the exam.
7) The bio-surveillance system electronically receives additional data (daily) related to the
activated specific procedures, e.g., laboratory data, data from questionnaires
administered by providers, etc.
8) The bio-surveillance system electronically sends health alerts to providers regarding the
detected event.
9) The bio-surveillance system electronically communicates with higher public health
authorities (state, federal) regarding the suspicious pattern and detected event as
determined by the public health response protocols.
10) The bio-surveillance system electronically sends health alerts to responders and to the
authorities of neighboring jurisdictions regarding the detected event as determined by
the public health response protocols.
Standards
The HITSP Biosurveillance Interoperability Specification, IS 02, focuses on a set of constrained
standards for implementation of near real-time, public health event monitoring to support
early detection, situational awareness and rapid response management across care delivery,
public health and other authorized Government agencies. It prescribes the process or
interaction that each primary stakeholder will invoke to capture, discover, anonymize and
transmit relevant data.vii The CPHS bio-surveillance database will be propagated with H1N1
alerts from the following systems:




Laboratory Information Management System (LIMS)
Clinical Information System (CIS) - Hospital Electronic Health Record (EHR)
Clinical Information System (CIS) - Electronic Medical Record (EMR)
CPHS Bio-Surveillance System Web Portal – NEDSS-
Use of standards and specifications by systems actor
The CPHS bio-surveillance system will be the “central” system that will be responsible for
collecting alerts from the outlying community providers and notifying the necessary community
stakeholders. All of the system actors will send messages from their respective messaging
systems utilizing a combination of the following standards and specifications (see the diagram
below for clarification what standard each provider is using):
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H1N1 Data Standards
LIMS
HL7, LOINC, UCUM,
HITSP/C35, HITSP/C36,
HITSP/C37
H
,
L7
D
IC
9
H
D,
ME
O
N
,S
CPHS biosurveillance
database
P /C
ITS
39
HL
7,
IC
D9
,
HTTP
SN
OM
ED
,
HI
TS
P /C
Hospital EHR
Provider Web-based
NEDSS entry portal
39
Provider EMR

LIMS will communicate with the CPHS database using:
o HL7 CDA R2
o IHE (LAB TF-3)
o Logical Observation Identifiers Names and Codes (LOINC)
o Unified Code for Units of Measure (UCUM)
o HITSP/C35, HITSP/C36, HITSP/C37

Hospital EMR will communicate with the CPHS database using:
o HL7
o ICD9
o SNOMED
o HITSP/C39

Clinic/Provider EMR will communicate with the CPHS database using:
o HL7
o ICD9
o SNOMED
o HITSP/C39

Web-based Bio-Surveillance Portal will communicate with the CPHS database using:
o HTTP
o HTTPS
The above standards are necessary to provider interoperability with the CPHS H1N1 biosurveillance alert system. They are used to realize direct information exchange, to provide the
transport mechanism, to specify the content and address security concerns.viii
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Description of standards and specificationsix
HL7 CDA R2 – The HL7 Clinical Document Architecture is an Extensible Markup Language (XML)based document markup standard that specifies the structure and semantics of clinical
documents for the purpose of exchange. CDA is one instantiation of HL7's Version 3.0
Reference Information Model (RIM) into a specific message format. Of particular focus for
HITSP Interoperability Specifications are message formats for Laboratory Results and Continuity
of Care (CCD) documents. Release 2 of the HL7 Clinical Document Architecture (CDA) is an
extension to the original CDA document markup standard that specifies the structure and
semantics of clinical documents for the purpose of exchange. CDA R2 includes a prose
document in HTML, XML schemas, data dictionary, and sample CDA documents. CDA R2 further
builds upon other HL7 standards beyond just the Version 3.0 Reference Information Model
(RIM) and incorporates Version 3.0 Data Structures, Vocabulary, and the XML Implementation
Technology Specifications for Data Types and Structures. For more information visit
www.hl7.orgx
HL7 Version 2.5.1 – Messaging Standard is an application protocol for electronic data exchange
in healthcare. It and prior versions have widespread use in the U.S. and internationally. Both
message formats and value sets / code tables (e.g., diagnosis type, gender, patient class, result
status, specimen collection method, abnormal flags, observation result status codes
interpretation, and timestamp format) are contained in the standard.
IHE (LAB TF-3) - The IHE Laboratory Technical Framework introduces a content Integration
Profile Sharing Laboratory Reports (LAB TF-3) that describes a clinical laboratory report as a
human-readable electronic document. This document, which may also contain data in a
machine-readable format, contains the complete set of final results produced by a clinical
laboratory in fulfillment of one or more test orders for a patient. This document is focused on
the sharing of sets of laboratory results in the form of a laboratory report structured document,
and is not intended to address ordering or return of laboratory results to the ordering provider.
For more information visit www.ihe.netxi
SNOMED CT - consists of a technical design, core content architecture and Core content.
SNOMED CT Core content includes the technical specification of SNOMED CT and fully
integrated multi-specialty clinical content. The Core content also includes a concepts table,
description table, relationships table, history table, ICD-9-CM mapping and Technical Reference
Guide.
ICD-9-CM The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD9-CM) is based on the World Health Organization's Ninth Revision, International Classification
of Diseases (ICD-9). ICD-9-CM is the official system of assigning codes to diagnoses and
procedures associated with hospital utilization in the United States.xii
LOINC - A database of universal identifiers for laboratory and other clinical observations. The
laboratory portion of the LOINC database contains the usual categories of chemistry,
hematology, serology, microbiology (including parasitology and virology) and toxicology; as well
as categories for drugs and the cell counts typically reported on a complete blood count or a
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MED INF 405 – Team Paper
cerebrospinal fluid cell count. Antibiotic susceptibilities are a separate category. The clinical
portion of the LOINC database includes entries for vital signs, hemodynamics, intake/output,
EKG, obstetric ultrasound, cardiac echo, urologic imaging, gastroendoscopic procedures,
pulmonary ventilator management, selected survey instruments and other clinical
observations.
UCUM - A code system intended to include all units of measures being contemporarily used in
international science, engineering, and business. The purpose is to facilitate unambiguous
electronic communication of quantities together with their units. The focus is on electronic
communication, as opposed to communication between humans.
HITSP/C35 - The terminologies in this component apply equally to both the HITSP/C36 Lab
Result Message and the HITSP/C37 Lab Report Document. The HITSP Technical Committee is
constructing a mapping between these two representations to make the correspondence
between data elements explicit. This mapping will be presented to the Health Level Seven (HL7)
committees that publish the two representations with the expectation that HL7 will maintain
the mapping.xiii
HITSP/C36 is a lab result message that is dependent on HITSP/C35-Lab Result Terminology, HL7
version 2.5.1 and HITSP/C154 HITSP Data Dictionary. The purpose for HITSP/C35 is to supply the
required vocabulary guidance information to be applied within the message exchange. HL7
version 2.5.1 defines the data structure requirement, and HITSP/C154 identified HITSP Data
Elements (DE) that map to the HL7 DE constrained by this component.xiv
HITSP/C37 is a lab report document that is dependent on the Integrating the Healthcare
Enterprise (IHE) Laboratory Technical Framework Volume 3 (LAB TF-3) Document-based
Transactions, Revision 2.0 – For Trial Implementation, August 16, 2007. The reason for this
dependency is that it is a composite standard. HITSPC/C37 is also dependent on HITSP/C35 Lab
Result Terminology as it supplies the required vocabulary guidance information to be applied
within the exchange document.xv
HITSP/C39 is patient encounter message for sending an encounter-based biosurveillance
message. The trigger for sending encounter-based bio-surveillance data is the updating of
patient-based data at the data source. In many instances the updating of data at the data
source will generate a local HL7 transaction.
Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed,
collaborative, hypermedia information systems. The World Wide Web Consortium and the
Internet Engineering Task Force (IETF), which defines HTTP/1.1 (the most commonly used
version), have coordinated the standards development of HTTP.xvi
Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer
Protocol with the SSL/TLS protocol to provide encryption and secure identification of the
server. HTTPS connections are often used for payment transactions on the World Wide Web
and for sensitive transactions in corporate information systems.xvii
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Usage example of standard (HITSP/C37)
Example of a HITSP/C37 Message from LIMS to CPHS xviii
The functional flow scenario from our LIM system submission of laboratory bio-surveillance
H1N1 test result to the CPHS bio-surveillance system is a necessary component of routine
public health reporting processes which typically requires an established trusted
communication channel prior to the actual transfer of bio-surveillance data being initiated.
The pre-conditions assume a laboratory has processed an H1N1 sample and the test result is
within the range and category of interest for bio-surveillance reporting as required by federal,
state, or local health departments. The laboratory is also assumed to have a LIM system that
can capture the information required to generate the report.
The specific data elements (DE) managed by the laboratory LIM system are expected to be the
source for information used in creating the bio-surveillance report.
Detailed contents of the bio-surveillance report to support this use case are included in the
HITSP/C37 Lab Report Document Component Specification.
HITSP/C37 Lab Report Document Component Specificationxix
HITSP/C37 component specification is to have laboratory and interpretation structured as
Extensible Markup Language (XML) document for interchange to meet requirement for human
and machine readability. The context also introduces properties of documents such as
persistence, non-repudiation, and unique identification of documents.
The component specification describes an electronic version of a laboratory report structured
as an electronic document following the IHE LAB TF-3 and HL7 CDA R2 standards and
specifications.
Laboratory documents for exchange are described in this section. Pre-conditions to the process
of exchanging a LIM system document are:




The order and specimen must have been received by the laboratory, and the
ordered test performed
The electronic laboratory result has been deemed releasable by the sender
The laboratory result conversion into CDA format has been accomplished
The repository must be capable of preserving data required by the Clinical
Laboratory Improvement Amendments (CLIA) that are subsequently sent in the CDA
HITSP/C37 is dependent on IHE LAB TF-3 and HITSP/C35. HITSP/C35 supplies the required
vocabulary guidance information to be applied within the exchange document.
HITSP/C37 Data Structure
A CDA document comprises a header and a body. IHE defines the header as:
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
Header identifies the patient, the clinical Laboratory that produced the report, the
physician that ordered the tests, the encounter in which the act was performed, and
other participants to this document (e.g. author, custodian, legal authenticator).
The body comprises 2 levels. IHE defines the level 2 body as:


The body is organized as a tree of up to 2 levels of sections, delivering humanreadable content of the report: Top-level sections represent laboratory specialties. A
top level section may contain either a single text block carrying all the results
produced for this specialty or a set of leaf sections.
In addition, any leaf section SHALL contain a level 3 entry that contains the
observations of that section in a machine-readable format.
The Level 3 entry may be a multimedia entry or a machine processable entry. IHE defines them
as follows:
21

Level 3 entries dedicated to multimedia rendering. A leaf section of the Laboratory
Report MAY have optional entries to carry the multimedia objects mentioned in
Level 2 narrative block, and provide their rendering. Multimedia rendering is based
on the observation Media element in an entry dedicated to that purpose.

And each leaf section of the Structured Body of a Laboratory Report MAY contain
one entry containing the machine-readable result data rendered in the section.
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MED INF 405 – Team Paper
Information Architecture
Clinician
CPHS Official
Clinician
Terminal
Clinician Terminal
Web Browser
HL7/XML | C35, C36, C37, C39
HTTPS
Web-based
NEDSS
NEDSS
Terminal
Application Interface
HTTPS
CIS
EAI
HL7
LIMS
EAI
HL7
CIS
LIMS
Enterprise Application Integration (EAI)
HL7
HTTP/
S
C35
C36
C37
C154
CPHS
BioSurveillance
Database
Database Tools
Report
Data Mine
System
Functions
CPHS Biosurveillance System
22
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H1N1 Disease Surveillance
MED INF 405 – Team Paper
Data Sets
The data sets that will be used are based on the recommended data elements as found in the
CDC’s Swine Influenza case report form dated April 30th, 2009. All specific codes and
vocabularies will be in accordance with Center for Disease Control’s document titled: “Swine
Flu (H1N1) Case Report Form – Standardized Vocabulary.”xx These data sets are listed below:
1)
2)
3)
4)
5)
6)
Demographics
Clinical Data (Signs, Symptoms)
Medical History (Immunization, Disease)
Diagnostic Findings (Lab Test, Lab Results)
Treatment
Epidemiology
Data Element Constraints
Data elements have limits placed on them and the values that may correspond within it.
These limitations are called constraints. For example, a data element bearing the
administrative “gender” could be limited to the concepts of “Male”, or “Female”.
Furthermore, these restrictions can be concrete as well, such as a specific value set that
must be used within the data element. For example, the administrative gender could be
limited to the HL7 defined value set indentified using the 2.16.840.1.113883.1.11.1 OID
(object identifier).xxi Listing the constraints related to all the data elements in the “Swine
Flu (H1N1) Case Report Form” would be too far-reaching and hence, it is not part of this
paper.
Definition of individual data elements
The individual data sets that make up the data elements are defined as follows:
Demographics
1)
2)
3)
4)
Date of Birth
Race
Ethnicity
Sex
Clinical Data (Signs, Symptoms)
1)
2)
3)
4)
5)
6)
23
Date of symptom onset
Signs and Symptoms
Was the patient hospitalized?
Was the patient admitted to the intensive care unit?
Did the patient require mechanical ventilation?
Did the patient die as a result of this illness?
H1N1 Disease Surveillance
MED INF 405 – Team Paper
Medical History
1) Did the case-patient receive influenza vaccine between September 2008 and March
2009? If yes:
a. Number of doses
b. Type of vaccine
2) Does the case-patient have any of the following?
a. Asthma
b. Other Chronic Lung disease
c. Chronic heart or circulatory disease
d. Metabolic disease (including diabetes mellitus)
e. Kidney disease
f. Cancer in the last 12 months
g. Immunosuppressive condition (HIV infection, chronic corticosteroid therapy,
or organ transplant recipient)
h. Other chronic diseases
i. Neurological disease
Diagnostic Findings
1)
2)
3)
4)
Leukopenia (yes or no)
Lyphopenia (yes or no)
Thrombocytopenia (yes or no)
Did the patient have any of the following tests?
a. Chest X-ray, If yes:
i. Normal
ii. Abnormal
b. Chest CT scan, If yes:
i. Normal
ii. Abnormal
5) Influenza testing
a. Test 1
i. Date collected
ii. State Lab specimen ID
1. Specimen Type
2. Test Type
3. Results
4. Influenza Type/Subtype
b. Test 2
i. Date collected
ii. State Lab specimen ID
1. Specimen Type
2. Test Type
3. Results
4. Influenza Type/Subtype
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b. Specimens sent to CDC
i. Indicate when and what type of specimens (including sera) were sent to
CDC and specimen ID
1. Date
2. Specimen type
3. State Lab Specimen ID
Treatment
1) Did the patient receive antiviral medications? If yes:
a. Drug (list provided)
b. Date initiated
c. Date discontinued
d. Dosage (if known)
Epidemiology
1) The following questions concern the 7 days prior to illness onset: (answer: yes, no or
unknown)
a. Did the patient travel to Mexico?
b. Did the patient have close contact (within 2 meter (6 feet)) with a person (e.g.
caring for, speaking with, or touching) who is suspected, probable or confirmed
swine influenza case?
c. Did the patient handle samples (animal or human) suspected of containing
influenza virus in a laboratory or other setting?
d. Has the patient had family members or close contacts with pneumonia or
influenza-like illness?
2) Household Transmission
a. How many people live in the household (include patient in this number)?
b. For each person in the household, besides the patient, record age, check
applicable symptoms if present anytime from 7 days before to 7 days after the
patient’s onset date, and record initial symptom onset date.
c. Have any of the patient’s household members been tested for influenza? If yes:
i. Person#
ii. Test date
iii. Test result
Data set sources
The following table lists the data sets, their constituent data elements, the system actor that
will house the data and the collection scenario for each data set.
Data Set
25
Data Element
Source
System(s)
Collection Scenario
H1N1 Disease Surveillance
MED INF 405 – Team Paper
Demographics Date of Birth
Race
Ethnicity
Primary: CIS
(Hospital,
Provider)
I. Obtained by provider during patient
encounter and registration, stored in
CIS by clinician
Secondary:
LIMS
(Laboratory)
II. Obtained at hospital registration,
stored in CIS
Sex
Data Set
Clinical Data
Data Element
Date symptom
onset
III. May be accessed by laboratory LIMS
through CIS interface
Source
System(s)
Collection Scenario
CIS (Hospital,
Provider)
I. Entered into CIS by clinician/provider
as a result of the patient encounter,
or hospitalization.
Signs and
Symptoms
(SNOMED Concept
Codes)
Was the patient
hospitalized?
Was the patient
admitted to the
intensive care unit?
Did the patient
require mechanical
ventilation?
Did the patient die
as a result of this
illness?
Data Set
Medical
History
Data Element
Received Flu vaccine
between 9/2008 and
3/2009?
(If so, # of doses?,
26
Source
System(s)
CIS (Hospital,
Provider)
Collection Scenario
I. Obtained by clinician/provider from
the medical history interview during
the patient encounter, stored in CIS
II. Obtained at hospital registration,
H1N1 Disease Surveillance
MED INF 405 – Team Paper
vaccine type?)
Existing Conditions?
stored in CIS by hospital admin
staff, data automatically ported to
CIS
 Asthma
 Other Chronic Lung
disease
 Chronic heart or
circulatory disease
 Metabolic disease
(including diabetes
mellitus)
 Kidney disease
 Cancer in the last
12 months
 Immunosuppressiv
e condition (HIV
infection, chronic
cortico-steroid
therapy, organ
transplant
recipient)
 Other chronic
diseases
 Neurological
disease
Data Set
Diagnostic
Findings
Data Element
Leukopenia (Y/N)
Lyphopenia (Y/N)
Thrombocytopenia
(Y/N)
Tests Taken?
27
Source
Collection Scenario
System(s)
CIS (Hospital, I. Provided by provider or hospitalProvider)
based clinician during patient
encounter as a result of the diagnostic
testing and treatment decisions made
by the clinician, stored in CIS by
clinician or staff
H1N1 Disease Surveillance
MED INF 405 – Team Paper
 Chest X-Ray
(norm, abnormal)
 Chest CT scan
(norm, abnormal)
Influenza testing?
 Date collected/
specimen ID
 Specimen type
 Test type
 Results
 Type/Subtype
(specimens sent
to CDC, when,
what type, ID)
 Date
 Specimen
 State Lab ID
Data Set
Treatment
I. Test orders are entered and stored in
the LIMS system when ordered by
clinician. Test orders are also stored
in CIS if ordered through
Secondary:
CIS (Hospital, II. Test results are entered and stored
Provider)
into LIMS system
III. Test results are transmitted to
clinician when finalized and stored in
the CIS
Data Element
Source
Collection Scenario
System(s)
Antiviral
CIS (Hospital, I. Provided by provider or hospital-based
Medication?
Provider)
clinician during patient encounter as a
result of the diagnostic testing and
 Drug – from list
treatment decisions made by the
provided
clinician, stored in CIS by clinician or
 Date initiated
staff
 Date discontinued
 Dosage
Data Set
Data Element
Epidemiology
Questions re: 7
days prior to onset
(Y, N, U):
 Mexico travel?
 Close contact?
 Handle samples?
 Family/close
contacts w/ flulike illness?
28
Primary:
LIMS
(Laboratory)
Source
Collection Scenario
System(s)
CIS (Hospital, I. Obtained by clinician/provider from
Provider)
medical history interview during the
patient encounter, stored in CIS
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MED INF 405 – Team Paper
Household
transmission
 Number of
inhabitants?
 Inhabitants w/ flu
symptoms?
 Inhabitants tested
for flu (number
tested, date
tested, test
result)?
29
H1N1 Disease Surveillance
MED INF 405 – Team Paper
Data flow diagram
H1N1 Confirmation Call
Updated H1N1 Case Information
email H1N1
Notification and
Clinician
Request for Details
H1N1Lab
Test Order
NEDSS
Via Lab’s
Data entry Web Interface
H1N1 Lab
Test Order
Clinical Data Entry
H1N1 Diagnosis
Web-based NEDSS Data
H1N1 Diagnosis
HITSP/C39
Internet Access
H1N1 Lab
Test Order
H1N1 Lab
Test Result
Clinical Information
System (EHR/EMR)
H1N1 Lab
Test Order
H1N1 Lab
Test Result
LIMS
EAI
Engine
CIS
EAI
Engine
Web-based NEDSS Entry
Form for CPHS
Biosurveillance System
Updated H1N1
Case Information
H1N1
Confirmation Call
Web-based NEDSS data
CPHS
EAI
Engine
H1N1 Test Order Alert
HITSP Alert
Messages
H1N1 Lab
Test Result
CPHS
Biosurveillance
System
Positive H1N1 Test Alert
NEDSS Web Alert
Updated H1N1 Case Data
CPHS Public Health Officials
H1N1 Lab
Test Order
H1N1 Test Order Alert
HITSP/C35
Laboratory Information
System (LIMS)
Positive H1N1 Test Alert
HITSP/C36, HITSP/C37
email H1N1 Notification and Request for Details
CPHS Biosurveillance System
Data Flows
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MED INF 405 – Team Paper
Endnotes
i
http://www.who.int/countries/eth/areas/surveillance/en/index.html
President’s Council of Advisors on Science and Technology. U.S. Preparations for 2009-H1N1 Influenza. August 7,
2009. Available at: http://www.whitehouse.gov/assets/documents/PCAST_H1N1_Report .pdf
iii
Accessed October 23, 2009 from:
http://www.medicalnewstoday.com/printerfriendlynews.pphp?newsid=167025
iv
http://www.hsph.harvard.edu/news/press-releases/2009-releases/businesses-problems-maintianing-operationssignificant-h1n1-flu-outbreak.html
v
http://www.cdc.gov/nedss/Archive/Supporing_Public_Health_Surv.pdf
vi
http://www.bt.cdc.gov/DocumentsApp/HAN/han.asp
vii
http://www.hitsp.org/ConstructSet_Details.aspx?&PrefixAlpha=1&PrefixNumeric=02
viii
HITSP/C35 Specification.<http://wiki.hitsp.org/docs/IS12/IS12-1.html>
ix
HITSP/C35 Specification.<http://wiki.hitsp.org/docs/IS12/IS12-1.html>
x
http://wiki.hitsp.org/docs/C37/C37-3.html
xi
http://wiki.hitsp.org/docs/C37/C37-3.html
xii
http://www.cdc.gov/nchs/icd/icd9cm.htm
xiii
HITSP/C35 Specification.<http://wiki.hitsp.org/docs/IS12/IS12-1.html>
xiv
HITSP/C36 Specification. <http://wiki.hitsp.org/docs/IS107/IS107-1.html>
xv
HITSP/C37 Specification. <http://wiki.hitsp.org/docs/IS77/IS77-1.html>
xvi
http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
xvii
http://en.wikipedia.org/wiki/HTTP_Secure
xviii
HITSP Biosurveillance Interoperability Specification Version 3.2. <http://wiki.hitsp.org/docs/IS02/IS02-1.html>
xix
http://wiki.hitsp.org/docs/C37/C37-3.html
xx
Swine Flu (H1N1) Case Report Form – Standardized Vocabulary ,
<http://www.cdc.gov/phin/activities/standards/documents/Swine%20Flu_H1N1%20Case%20Report%20%20Std_Vocabulary%20(2).pdf>
xxi http://wiki.hitsp.org/docs/TN903/TN903-5.html
ii