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By: David Cardenas, Abdul
Malik Shakir and Gora Datta,
Department of Health
Services-Public Health, Los
Angeles County, Los
Angeles, CA
Challenge
Public Health applications have
been previously developed to assist
public health programs in meeting
individual program’s goals and
objectives. This has led to the
development of systems that collect
data only for explicit purposes,
without clear efforts to improve the
integration, efficiency, and
usefulness of public health data.
The evolution of these disparate,
fragmented public health data
systems has led to duplication of
effort, and placed limitations on
local public health agencies to
accomplish the mission of
safeguarding and improving the
health of the community and to
respond effectively to large-scale
threats to public health.
The Los Angeles County
Department of Health Services has
created an initiative to support
consolidation of critical clinical and
public health data across diverse
individual IT systems [4]. The
adoption and integration of
knowledge-based decision support
systems such as Data Warehouse,
Business Intelligence toolset, and
use of a central master person
identifier are promoted. This
initiative requires that existing
investments in legacy systems be
leveraged and merged with
standards-based web enabled
systems to provide a synchronized
view of public health data and
resources across all program areas.
Solution
The Los Angeles County (LAC)
Operational Data Store (ODS)
architecture is based upon the nine
elements of the Public Health
Information Network initiative
(PHIN) published by Center of
Disease Control and Prevention
(CDC) and influenced by CDC’s
National Electronic Disease
Surveillance System (NEDSS)
[2, 3]. Deployment of the ODS and
related components introduces an
integrated standards-based system
in LAC that provides a synchronized
view of public health data and
resources across all program areas.
The Operational Data Store (ODS),
a component of PHIN architecture,
will eventually hold all operational
data for the public health program
areas and include an Operational
Data Store Application Program
Interface (ODS-API) [5]. The ODS-
API provides an interface to store
and retrieve data from the ODS
using the logical data model and
without the detailed knowledge of
the underlying relational tables.
ODS-API provides an interface to
the ODS for all other components of
the framework.
Architecture
Deployed
ODS is the core component of the
PHIN architecture. The strategic
objectives of PHIN are: Enhance
the ability of Public Health to
conduct surveillance for bioterrorism
and other communicable diseases;
Assist in the control of disease
outbreaks and offer critical surge
capacity for the tracking of
epidemiological information;
Broaden the communications
capabilities of the public health
A Standard (HL7 V3) Based
Public Health Information
Network for Los Angeles County
Department of Health Services:
Public Health – Case Study
42
State/Local
system; Implement mechanisms to
support broad CDC initiatives while
complying with requirements of
local jurisdictions; Align the public
health system with federal directives
and national initiatives.
Key components of the architecture
include: 1) Infrastructure &
housekeeping services to provide
authentication, directory and
security services for the system and
enable single sign-on. 2) A
knowledge management module
that manages translation and
mapping of data from other systems
to the ODS in a standardized
format. 3) HASTEN provides the
single sign-on portal for
authentication & entry into the
system. It also incorporates an
event alerting mechanism. HASTEN
provides the human interface. 4)
HEDEX provides an electronic
interface to systems that need to
send data to and receive data from
the ODS. 5) Analysis and
Visualization services provide data
analysis, reporting and GIS
services. 6) Unique Person
Identifier is an effort at the LAC to
cross-index and assign unique
identifiers to individuals who receive
care or are referred to LAC
facilities. 7) Data Warehouse at
LAC is a patient-centric data store
that pools data from hospitals,
emergency care and public health
programs. 8) The Incident
Management System is the core
component of the PHIN architecture
that provides case management
and program area support for
managing disease specific
interactions.
A Standard (HL7 V3) Based Public Health Information Network
for Los Angeles County
Department of Health Services: Public Health – Case Study
43
State/Local
Figure 1: Los Angeles County Public Health Information Network Architecture Overview
Infrastructure & Housekeeping Services
Sign-On Module
Notification and
Alerting Module
Analysis and
Visualization
Module
Operational
Data Store
Enterprise Data
Warehouse
Health Electronic
Data Exchange
(HEDEX)
External Partners
and Other County
Deprartments
Master Person
Identifier
Public Health Nursing
Common Case Reporting
and Status Tracking (CCR)
VCMR STD TB EDS
XML
SQL/ETL
SQL/ETL
HASTEN
SQL/ETL
XML/ETL
SQL/ETL
Incident Management
System
HL7 2.x/3
File Transfer
XML
ODS:
The ODS provides persistent
and patient-centric storage for data
from multiple public health
programs. The ODS is a relational
database designed in an abstract-
extensible style consistent with the
HL7 V3 Reference Information
Model (RIM). The database is
implemented in three phases. In
the first phase, the ODS merely
mimics the data currently
maintained by existing Program
Area Modules (PAMs), such as the
EDS [1]. In the second phase, the
ODS is expanded to support the
expansion of PAM capabilities and
the introduction of Common Area
Modules (CAMs), such as
Knowledge Management System.
In the third phase, the ODS
replaces PAM specific local
databases as the database of
record for non-transient PAM-
specific data. PAM specific
databases are used for transient
data only. The ODS also includes a
staging area for the temporary
storage of data received from
external systems and data intended
for export to external applications or
bulk transport. Structured Query
Language/Extract Transform and
Load (SQL/ETL) tools are used to
transform data to and from the
persistent storage areas of the
ODS.
ODS-API:
The ODS-API handles
healthcare transactions by exposing
the HL7 V3 RIM objects that can be
manipulated by client applications
and provides the ability to persist
the transaction in a relational
database using Object-Relational
Mapping technology, freeing the
client application from having to
deal with the physical data model
[6]. Initial scope of this layer is to
provide an XML message interface
for incoming and outgoing
messages from the other
components of the PHIN System.
As the development matures and
the interface stabilizes, the ODS-
API, in its final form, will be
published as the only interface to
the LAC Public Health ODS and all
new applications developed
internally and externally will be
required to use this Interface to
store and retrieve data to/from the
LAC Public Health ODS.
The final steps will be the
implementation of the ODS-API with
Reference Information Model (RIM)
Interface towards automating the
population of ODS. The ODS-API
will allow newly developed public
health applications to directly store
the operational data in the ODS and
will remove the need of duplicate
data stores. This ODS-API will be
built on top of ODS-API layer which
consumes the XML messages for
healthcare events.
Benefits
The ODS is under deployment and
the legacy systems are now being
integrated with it. The ODS-API is
under development. The Reporting
services have been deployed and
can report on ODS data. Several
systems will be integrated into the
infrastructure over the coming years
including PAMs to support
integrated case management
activities for Public Health.
The PHIN compliant systems will
specifically address the following [7,
8]: a) The development of a web-
based system architecture for
Public Health programs and health
districts that is capable of
supporting electronic data exchange
from public health partners using a
HL7 based integration hub, b) the
development of management tools
and applications to assist public
health response and c) recovery
activities while providing resources
to support departmental integration.
The PHIN/NEDSS systems will
leverage individual system
components for the overall
improvement of public health
information technology
infrastructure while contributing to
the development of a common
enterprise data warehouse that will
unify public health and clinical data
under a unique person identifier.
There are multiple systems in place
that support communications for
public health labs, the clinical
community, and state and local
health departments. However, most
of these systems operate in
isolation. Numerous benefits will
start accruing as parts of the
system are built and integrated into
the business processes of the local
health services. The
implementation of a unifying system
will further improve access to
laboratory data and response
protocols, advanced capabilities for
rapid notification of public health
partners, response agencies, the
media, and the general public.
There will be an enhanced
capability to train public health staff
and a uniform data exchange
standard for exchanging data
between the public health partners.
44
A Standard (HL7 V3) Based Public Health Information Network
for Los Angeles County
Department of Health Services: Public Health – Case Study
State/Local
Real-time collection of data from
heterogeneous healthcare systems,
program area modules,
consolidation and cross-indexing of
data, integrated directory
infrastructure for public health
personnel and identity
management, integration of related
healthcare and patient data from
heterogeneous systems into a
common interface, provide access
through a ubiquitous web-based
portal that will obviate the necessity
of client-side implementations of
application systems, provide a
mechanism to disseminate critical
and public-interest information to
the community in general are
additional benefits.
Conclusion/
Lessons Learned
The primary objectives of this
initiative was to enhance the ability
to conduct public health
surveillance, provide electronic
applications to assist in the control
of disease outbreaks, develop
advanced training tools for public
health partners, and broaden the
communications capabilities of the
public health system in Los Angeles
County in order to effectively
prepare and respond to bioterrorism
and other public health
emergencies.
It is expected that the Public Health
Information Network System effort
will expedite the consolidation of
critical clinical and public health
data across diverse individual IT
systems. It will leverage existing
investments in legacy systems and
merge them with standards based
web enabled systems to provide a
synchronized view of public health
data and resources across all
program areas. The ODS can be
queried for a person-centric view of
health-related data across all
program areas. The visualization
services provide a dashboard view
and drill-down report capabilities for
decision support and alignment of
critical public health resources.
The use of a model driven
[http://www.omg.org/mda/] Service
Oriented Architecture [http://www.
service-architecture.com/index.html]
has allowed the County to take
advantage of state-of-the-art
information technologies while at
the same time leveraging the
investment made in its legacy
application system. The use of
industry standards positions the
system to be interoperable with
similar efforts conducted in other
jurisdictions such as in neighboring
Counties, the state of California,
and the CDC.
A difficult issue to overcome was
the inertia and tradition of autonomy
enjoyed by program area leaders.
We were fortunate enough to
benefit from the coincidental coming
together of three factors. First, the
vision expressing the necessity of
data sharing and leveraging data as
a department wide asset was
clearly communicated by the
highest level of the County
management. Second, CDC’s effort
to define standards for use in
enabling a public health information
network had reached a level of
maturity that was useful for our
purpose. And finally, the national
recognition of the vulnerability of our
public health system motivated
Congress to allocate the funds
necessary to underwrite the cost of
development. Without these
influences, the project would not
have achieved the benefits so
urgently needed.
Acknowledgements
This work was performed by
CAL2CAL Corporation at the LAC-
Department of Health Services-
Public Health. The ODS and ODS
related applications are developed
under a grant from the CDC to state
and local jurisdictions to support
public health preparedness and
response to bioterrorism [4]. This
work was done in collaboration with
Public Health Information Systems
and Bio-terrorism Preparedness and
Response Initiative, LAC
Department of Health Services.
For more information contact David
Cardenas at dcardenas@ladhs.org;
or Gora Datta at gdatta@ladhs.org,
Los Angeles County Public
Health. ■
45
A Standard (HL7 V3) Based Public Health Information Network
for Los Angeles County
Department of Health Services: Public Health – Case Study
State/Local
References [1] Los Angeles County Department
of Health Services, Public Health
Information Systems, [a] SARS-
EDS Software Requirement
Specifications v1.0.2, October
2003;
[b] SARS-EDS Functional
Document v1.0.2, October 2003
[2] Public Health Information
Network: An Overview, published
article at http://www.cdc.gov/
phin/index.html .
[3] National Electronic Disease
Surveillance System, “The
Surveillance and Monitoring
Component of the Public Health
Information Network”, published
article of http://www.cdc.gov/
nedss .
[4] Los Angeles County Department
of Health Services, Public Health
Information Systems, PHIS
Action Plan for Bio-terrorism
Preparedness Initiative – The
application of NEDSS
architecture to Public Health
Information systems in Los
Angeles County, March 2003
[5] Los Angeles County Department
of Health Services, Public
Health, Bio-terrorism Prepared-
ness & Response Unit, ODS and
ODS-API design and architec-
ture documents, April 2005
[6] Beeler, George W; Huff, Stan;
Rishel, Wesley; Shakir, Abdul-
Malik; Walker, Mead; Mead,
Charlie; and Schadow, Gunther,
HL7: Message Development
Framework, published article on
http://www.hl7.org/library/mdf99/
mdf99.pdf .
[7] Health Alert Network: Public
Health Information Technology,
Functions and Specifications (for
Emergency Preparedness and
Bioterrorism) February 14, 2002,
published article on http://www.
cdc.gov/cic/functionsspecs/IT_
Functions_Specifications_final_
21402.pdf .
[8] Los Angeles County Department
of Health Services, Public
Health, Bio-terrorism
Preparedness & Response Unit,
Bio-terrorism Preparedness and
Response Initiative – The
application of PHIN Standards &
NEDSS Architecture towards
integrating Pubic Health
Information Systems in Los
Angeles County – Program Plan,
March 2004
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A Standard (HL7 V3) Based Public Health Information Network
for Los Angeles County
Department of Health Services: Public Health – Case Study
State/Local
