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Posts Tagged ‘CDA’

EHR to Bridge the Two Parallel Worlds

November 6th, 2009

These days I am spending some time on Process Improvements at Life Sciences and Pharma Companies. While doing so I noticed how much the Healthcare reform is going to help Life Sciences industry, indirectly.

 
Historically Life Sciences and Healthcare industry have been two strange and detached worlds.
But EHR related activities and standardizations, such as HL7, are creating more and more touch points for bringing these two parallel worlds together. 
 
The interoperability between EMR and CTM systems, and resulting interactions between Site Investigator and Primary Physician during Clinical Study are some of the obvious benefits.
 
On the technical side, I see CDA and CDISC to gradually converge on data structure, while utilizing XSLT for transformation at the end points to integrate clinical research data and health care data.
 
 

 

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Clinical Document Architecture (CDA) explained

October 28th, 2009

Clinical Document Architecture (CDA) is an XML-based standard used for clinical document exchange within Health Level Seven framework. 

 
CDA has three levels of document definition, distinguished by the degree of granularity of the markup. Level One providing the least structure and Levels Two and Three providing increasing granularity.
 
Level One consists of Header, Body and HL7 Datatypes
 
Level Two includes Domain specializations 
 
Level Three includes full document semantics aimed to meet the machine processing requirement
 
 
HL7 Datatypes are defined for:
 
- Character strings and display data
- Codes and identifiers 
- Quantities
 
And Coded CDA components or elements are based on (SNOMED) and have the two-letter ending "cd". 
 

Here is an sample CDA level three:

 

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What does HL7 enablement means?

October 23rd, 2009
HL7 is about moving data, in form of messages, between software systems within clinical environment. In other words it is a messaging standard that enables clinical/medical applications to exchange data. 
 
Information sent using the HL7 is packaged as a collection of one or more messages, each of which transmits one record or item of health-related information. Examples include patient information, patient visit data. laboratory record and billing information.
 
HL7 standard specifies both exchange mechanism as well as message format and data structure.
 
The HL7 transport mechanism relies on an Event-Driven protocol, typically based on MLP or MLLP (Minimal Lower Layer Protocol) over a TCP/IP socket connection. (See Apache Camel project for an open source implementation of MLLP protocol)
 
MLLP act as a wrapper around HL7 messages to introduce a notion of atomicity over TCP/IP (which is a "stream-oriented" connection).
 
The HL7 requires every application that accepts a message to send an Acknowledgment message back to the sending application. The sending application is expected to keep on sending a message until it has received an Acknowledgment message (referred to as ACK).
An acknowledgment message consists of two parts:
1) An MSH segment, which contains information about the sending and receiving applications and a MessageID
2) An MSA segment, which indicates whether the message was accepted or rejected
The acknowledgment message should not be sent until the data in the HL7 message has been read and consumed.
 
 
The protocol relies on "open system architecture", meaning that anybody can interface with the system using appropriate protocols, independent of the vendor
 
 
Each HL7 message is made up one or more segments, which are the building blocks of HL7 messages. And each segment consists of one or more Fields.
Segments group related information together, for example the PID segment contains information patient information such as ID numbers, name, address and date of birth.
 
In the following HL7 example message, you can see that each HL7 segment is located on it’s own line.
 
Example: (MSH, PID, OBR, OBX)
 
MSH|^~\&|GHH LAB|ELAB-3|GHH OE|BLDG4|200202150930||ORU^R01|CNTRL-3456|P|2.4
PID|||555-44-4444||EVERYWOMAN^EVE^E^^^^L|JONES|19620320|F|||153 FERNWOOD DR.^^STATESVILLE^OH^35292||(206)3345232|(206)752-121||||AC555444444||67-A4335^OH^20030520
OBR|1|845439^GHH OE|1045813^GHH LAB|15545^GLUCOSE|||200202150730|||||||||555-55-5555^PRIMARY^PATRICIA P^^^^MD^^|||||||||F||||||444-44-4444^HIPPOCRATES^HOWARD H^^^^MD
OBX|1|SN|1554-5^GLUCOSE^POST 12H CFST:MCNC:PT:SER/PLAS:QN||^182|mg/dl|70_105|H|||F
 
 
The latest release of HL7 (V3) mandates both Human and machine-readable data structure. As such the documents are structured in a format referred to CDA, or "Clinical Document Architecture", based on XML.  (See my other articles on CDA topic)
 
CDA documents are not birth-to-death aggregate records, but a means for packaging information for transmission. They can include text, images, sounds and other multimedia content.
 
CDA documents are typically a MIME encoded payload within an HL7 message.
 

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