Transcript A Summary Care Record Architecture based on HL7 CDA and SOA

Mr. Peter Given
Computing and Mathematics Department
Institute of Technology, Tralee
Introduction
 This paper shows how
 Service Oriented Architectures can be combined with
 the HL7 Clinical Document Architecture to facilitate
 the sharing of Summary Care Records between health
care information systems
Goals
 The solution demonstrates that
 A federated architecture based on SOA and coding
standards is a viable alternative
 to a centralized record architecture for the sharing of
summary care records
System Architecture
 The design describes a system that facilitates the
sharing of documents from the electronic medical
record between GPs and other healthcare providers
(Out of hours, emergency etc)
 The architecture facilitates storing healthcare data
locally and querying the data via an indexing
mechanism.
Data Layer
 The Data layer involves the capture and storage of
patient information in a GP Information System
 An Open source GP Information System was chosen to
represent legacy open source GP Systems (openEMR)
OpenEMR
• A free open source medical practice management and
electronic medical records application
(www.openemr.org)
• Licensed under GNU GPL
• Operates in Linux, FreeBSD, MacOS X and Windows
• A client/server architecture written in PHP with a
mySQL database – downloadable as a WAMP
application
OpenEMR
 The system is being used successfully at a number of
sites [86,87,89].
 A number of commercial companies are also
supporting the software [88,89,90].
 Not based on any EHR Standards but has some
support for coding standards
Functionality of OpenEMR
 The application stores
 patient demographic data
 patient encounter information
 vital signs
 laboratory results
 prescriptions and allergy information.
 The system also allows the management of
appointments and the generation of reports.
OpenEMR
Interfacing to OpenEMR
• The project entailed building an Interface Engine was
developed in order to extract:
• A Summary Care Record (SCR).
–
This will hold patient demographic data along with known
allergies and any medications prescribed in the last 6 months.
• A Prescription Record (PR).
–
This will contain demographic details and prescription
information that can be forwarded to a pharmacy system.
– A Patient Index for the SCR
Interfacing to OpenEMR
Index
SCR
Interfacing to OpenEMR
 The HL7 Clinical Document Architecture was chosen
as the document architecture standard.
 The Interface Engine retrieves data from openEMRs
databases and construct CDA conformant documents
using the CDA schema
HL7 CDA
• “The HL7 Clinical Document Architecture (CDA) is a
document markup standard that specifies the structure and
semantics of "clinical documents" for the purpose of
exchange” (HL7 website)
• A CDA document can include
•
•
•
•
Text
Images
Sounds
other multimedia content.
• Document-level, section-level and entry-level templates
available
• The content of CDAs defined in the HL7 Reference
Information Model and HL7 Data Types
CDA Structure
•
•
•
<ClinicalDocument>
... CDA Header ...
<StructuredBody>
•
<section>
•
•
•
•
•
•
/section>
<section>
•
•
•
•
<text>...</text>
<Observation>...</Observation>
<Observation>
•
<reference>
•
<ExternalObservation>...
•
</ExternalObservation>
•
</reference>
</Observation> <
<section>...</section>
</section>
</StructuredBody>
</ClinicalDocument>
Summary Care Record as a CDA
document
 The Summary Care Record
 Header

Title, Time, Confidentiality Code, Version Number, Record
Target (PatientRole, Patient Name, Gender, Birth Date),
Provider Organization, Author, Custodian, Legal
Authenticator, Encounter Information
 Section

Allergies and Adverse Reactions
 Section

Medications
Prescription Record as a CDA
document
 The Prescription Record
 Header

Title, Time, Confidentiality Code, Version Number, Record
Target, Prescription Provider Organization, Author, Custodian,
Legal Authenticator, Encounter,
 Section

Prescription Information
 drug name, quantity, dosage, refills and notes
Interfacing to OpenEMR
Index
SCR
Implementing the interface
• The Interface Engine was coded using PHP/DOM and
using a CDA document/section template schema
• The mapping from the openEMR database to the CDA
schemas was incomplete as the database did not hold
all the data specified in the CDA document schema.
• For example openEMR currently does not store clinical
codes with separate parts of the medical record so the
code fields in the CDA documents were left empty
Mapping inconsistencies
 Also the openEMR system stores dosing intervals as
• qid, bid, q3h
 while the CDA document needs these intervals to be
represented as time periods and unit (e.g. 3 hours).
Designing the Communication
Layer
 The Communication layer was designed in two parts.
 MPI Subsystem :The first part is the design of a
distributed Master Patient Index
 Record Retrieval Subsystem : The second part of the
design allows the user to retrieve the Summary Care
Record or prescription record using a Service Oriented
Architecture.
Master Patient Index Subsystem
• The Master Patient Index was designed on top of a
peer-to-peer network called the GP Peer Group.
• A GP with the correct credentials can join and leave
the peer network.
• The GP can then publish patient indices to the
network.
• The index advertises the existence of a Summary Care
Record for a patient and the endpoint address for that
record
Patient Index
• The patient index is designed to hold the following
information:
– document type etc
– The patients’ surname and first name
– The patient’s date of birth
– The patient’s PPS number
– The organisations’ id and name
– The endpoint where the full Summary Care Record can be
found.
• The information to build the index was extracted from
the openEMR system by the Interface Engine.
Generating Master Patient Index
Index
SCR
Generating a patient index from
OpenEMR
 The index information is initially retrieved from the
openEMR Clinical Information System using the data
layer interface as described above
 The index information is wrapped in an XML message.
A typical message is shown below:
Example Mater Patient Index
• <?xml version="1.0" ?>
– <SCR_Advert>
– <Document_CDA_Type>11488-4</Document_CDA_Type>
– <Document_Name>Summary Care Record</Document_Name>
– <Document_Description>Clinical
Document</Document_Description>
– <Patient_Surname>Bloggs</Patient_Surname>
– <Patient_Firstname>Joe</Patient_Firstname>
– <Patient_DOB>19670425</Patient_DOB>
– <Patient_PPS>1</Patient_PPS>
– <Organisation_ID>6</Organisation_ID>
– <Organisation_Name>givens sugery</Organisation_Name>
– <Endpoint>http://localhost:8080/ccx/mySCRInterface</Endpoin
t>
• </SCR_Advert>
Peer Advertisement
• The peer-to-peer software uses this information to generate
a peer advertisement which appends the following
header
•
•
•
•
<?xml version="1.0" ?>
<!DOCTYPE SCRAdvertisement>
<SCRAdvertisement xmlns:jxta=http://jxta.org>
<Advert_ID>urn:jxta:uuid59616261646162614E50472050325033272C475C1C344417800
08001</Avert_ID>
• MPI Infromation
• </SCRAdvertisement>
Peer to peer network
 A node can both publish to and search this network for
indices.
 To search for a particular patients SCR a discovery
message is propagated to all peers in the network.
Searching for a Patient Index
• The metadata contained within the index will improve
the search results from the discovery process.
• Once a peer has retrieved the index for a patient the
endpoint information is retrieved from the index.
• The second part of the communication layer will now
use this endpoint to retrieve the actual Summary Care
Record from the system in which it is stored.
Implementing MPI Application
 The MPI application itself consists of Java Swing
components that implement a Graphical User
Interface, along with calls to the JXTA API to join the
GP Peer Group network and to publish/discover
advertisements on the network.
Searching for a patient summary
care records
• Once the user provides values the peer sends a discovery
•
•
•
•
message to the other peers on the sub-network.
Any Rendezvous peers on the local sub-network will
further propagate the discovery message to other subnetworks they know about.
Any advertisements that match the surname/PPS number
are returned to the requesting peer.
Clicking on a particular patient from this list will show the
endpoint where the full Summary Care Record can be
found.
This endpoint information is now presented to the Web
Service client to retrieve the patient’s full Summary Care
Record
Security in the Peer Network
• The JXTA configuration requires a username and
password. A certificate may also be required.
• Once the peer starts up it can issue discovery messages
to locate other peer groups it may wish to join.
• The peer groups enforce a second level of security. The
user must supply a login name and password to join
the GP Peer Group.
Record Retrieval Subsystem
 SOA is used to deliver the Summary Care Record
 A client program that knows the endpoint address can
send a message to a Web Service on the GP site to
retrieve the Summary Care Record as a CDA document
SOA Solution
• A Web Services Server called Cape Clear was used to
•
•
•
•
build the SOA
The Web Service was defined in WSDL using Cape
Clear Studio.
The Web Service was implemented in Java and uses
the SOAP protocol at the messaging layer.
A Web Services client was built in Java
It generates SOAP requests which are sent to the sever
and the response contains either a Summary Care
Record or a Prescription Record
Retrieving the Summary Care
Record
 The Web Service had two services;
getSumaryCareRecord and getPrescriptionRecord.
 Both services require the patient’s PPS number (a
java.String) and the patient’s surname (java.String).
 The service returns a CDA documents (also as a
java.String) if one exists
Integrating the CDA record
 A reverse process to that taken to generate the data at
the data layer could be followed in order to integrate
the data with a local system.
 For this project it was enough to be able to view the
record
Viewing the Record
 Once the record is saved the user can finally view the
file.
 A standard XSL transform is attached to the file.
 The transform creates an HTML document that can be
viewed by any browser.
 The document can also be printed out.
Application areas
 Out of Hours Services – telephone triage etc
 Emergency Services
 Community Nursing
Conclusions: Advantages
 GP buy in
 can maintain their systems of choice (open source or
commercial)
 GPs can maintain their records locally (pull model)
 Healthcare Standardization
 CDA for clinical document exchange
 Other summaries can be implemented easily
 Technology Standardizations
 SOA and Web Services
 Distributed MPI with location information
Conclusions: Challenges
 Technical barriers
 Each GP system requires an interface Engine to generate
CDA documents

GP database may not hold required information
 GP Communications System is a hybrid SOA/P2P
solution


Security
Cost
 Distributed MPI with location information
Questions?