IHE Profile – ITI 8 (Patient Identity Feed)

ITI-8 is the HL7v2 format of ITI-44. Both ITI-8 and ITI-44 performs same action (i.e) Sending Patient Identity Feed. Based on the requirement of HIE, the EHR’s are expected to send the corresponding data. Some HIE expects ITI-8 (HL7v2 format) format and some HIE expects ITI-44 (HL7v3 format).

While communicating this message from an EHR entity to HIE, sometimes the HIE expects data to be sent in a VPN tunnel as IP/PORT socket connection. At times, the data communication happens through webservices interaction where the HIE will expect the HL7 data to be bind inside a soap envelope and then communicate to them.

This message is a transaction between EHR to HIE, EHR is described here as Patient Identifier Cross-Reference Consumer and HIE is described as Patient Identifier Cross-Reference Manager as well as Document Registry. Even though the working of  Patient Identifier Cross-Reference and Document Registry are not the same.


What exactly is Document Registry?

The Document Registry is an Actor that (actually a software/Database) maintains metadata about each registered document in a document entry or each patient records. Note that it maintains only meta-data (index of main data). The Document Registry responds to queries asked to it regarding documents meeting specific criteria.

What is Patient Identifier Cross Referencing (PIX) ?

The concept of transmitting the patient identifier information (patient id) from patient identifier source (EHR in our scenario) to the patient identifier cross reference manager is called Patient identifier cross referencing (so called PIX)

The Patient Identifier Cross Reference Manager is basically a software that receives data from any patient identity source and provides the data to document registry for performing query operations as shown in the picture below:


Actions performed in ITI – 8 :

The EHR will send the HL7 ADT messages to the HIE to do the following activities:

  1. ADT^A01 – Patient Admit Message
  2. ADT^A04 – Patient Registration Message
  3. ADT^A05 – Patient Pre-Admission Message
  4. ADT^A08 – Patient Update Message


But note that, in real-time an HIE might or might not adhere to this IHE profile standards.

Let’s logically discuss the above statement.

A04 : A “register patient” message (A04 event) signals that the patient has arrived or checked in as an outpatient, recurring outpatient, or emergency room patient. This message contains the information of patient as well as other information like next of kin, insurance or guarantor information as well.

A08 : Whenever any important information related to the patient is updated then this will be communicated as A08 message (for eg: visit information of patient, name, date of birth, or any information related to the patient).

Scenario :1
consider a scenario, Where a patient named zzzz is registered in a hospital and his details are sent to the HIE in the form of ADT A04 message.
Now, no demographics information of a patient zzzz is changed except his physical location upon which he was admitted. Like he is moved from Bed Number 305 to 405. In this case, it does not make sense to send this message as patient update because all the demographics fields are intact and same. And it is good to send an A02 message a Patient Transfer Message instead of Patient Update Message.

When A02 is sent, then it makes more sense because this message will contain change in assigned patient location in PV1-3 segment, while the old patient location appears in PV1-6-(prior patient location) and other demographic changes will be same.

According to HL7, if only the patient location change happens then EHR is expected to send an A02, but if the location change and demographic change both happened, then EHR should send an A08, But never both the messages i.e both A08 and A02 shouldn’t be sent.

Reference : http://www.hl7.eu/refactored/ch03.html

Similarly, If the patient is going to a temporary location (such as the O/R, XRAY, LIMBO, the HALLWAY) it is recommended that the A09 (patient departing tracking) and A10 (patient arriving tracking) events be used instead of A02.

But in the diagram provided above is IHE profiles suggested as per the document Vol2a there is no ADT A02 specified. Which makes this topic even more debatable.

Scenario 2:

Consider a scenario, where patient’s mother name is updated here patient’s mother is a Next of Kin, basically NK1 segment is changed. According to the above diagram, we have to send this as ADT^A31 message.

But, by the definition of ADT^A31 it is shown that it is “An update of any person information & the person need not be patient”. Which means it can be a patient as well. Now, to send the change of mother name, the EHR have the license to send either A31 or A08.

Reference : http://www.hl7.eu/refactored/ch03.html

An A08 (update patient information) event should be sent and/or negotiated as necessary to provide for implementation and application specific needs.

The right way to proceed this ITI-8 transaction is to get the details clarified from the HIE or the EHR person to determine what message to be sent based on the HIE acceptance.

A01 : The ADT A01 message will be used only for Inpatients. In other words this message is for ‘admitted patients only’. Not for clinic visits or outpatients.

A05 : The ADT A05 is a pre-register message, if the patient is scheduled for an operation, then the operation theater, setup and post-operation bed setup all information will be sent in this message.



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