PHC-Hub logo PHC Hub Administrator User Guide (v. March 2018)

PHC Hub HL7 Message Format

PHC Hub is built to accept messages in HL7 version 2 format. It also supports alternate formats that follow the structure and business rules of immunization HL7 messages. PHC Hub translates data from a message into an internal data structure that is modeled after HL7 messages. Data from other formats, such as flat-file, is translated to the internal data representation. Further processing on the data is performed on the internal model and is not HL7 specific.

For older versions of GE Centricity that don't support standard immunization messages, some additional configuration is required. See Workaround for GE Centricity in the PHC Hub User Guide.

Messages Accepted

PHC Hub accepts the following HL7 messages:

Message	Description
VXU	Patient Vaccination Record Unsolicited
VXQ or QBP	Query for Patient Vaccination/Immunization History Record. Uses the data in QRF-5 to match records.
DFT^P03	Post Detail Financial.
ADT	Admission/Discharge/Transfer.
ORU	Unsolicited Observation Result.

PHC Hub may reply to a v2.5.1 QBP with the following HL7 message:

Message	Description
RSP	Query Response with an RSP message is returned with a profile indicating that querying systems should determine if: A high-confidence match was obtained One or more low-confidence matches are returned in a list No results could be found for the patient vaccination record

Messages Sent

PHC Hub may send the following HL7 message:

Message	Description
VXU	Unsolicited vaccination record update.

Patient Record (VXU, DFT, ADT)

The patient record update messages should only be sent to PHC Hub when at least one of the following conditions applies:

When the sending system's organization has just provided some type of service for the patient
When the patient's vaccination record has changed
When the sending system wants to send patient records as part of an initial data load. This should be coordinated with registry staff to process without changing ownership

The sending system should not send their entire patient population each time it wants to update the registry. This causes the registry to change the patient's medical home when it wrongly assumes that the sending entity has recently provided services for the patient.

Patient Identifiers

PHC Hub looks in the Patient Identifiers list (PID-3) field for two key patient IDs to identify a patient:

The ID the remote application uses to uniquely identify the patient. This field is required
The ID the IIS uses to identify the patient. Since most systems do not store this ID, it is not normally sent. This ID is optional

Patient Vaccination Record (VXU)

The VXU message contains one patient record (PID segment) and the patient's vaccination record. This is the preferred message for sending vaccination and patient records, even when a patient has no vaccinations. PHC Hub sends and prefers to receive complete vaccination records; this way, sending systems don't need to track which vaccinations the IIS has and doesn't have.

Post Detail Financial (DFT)

PHC Hub supports the DFT message for billing systems that don't currently export VXU messages. The DFT message includes patient demographic data and services recently performed, which may include vaccinations.

Admit/Discharge/Transfer (ADT)

The ADT message is normally used by hospitals to communicate patient demographic information to various internal systems. The ADT message contains no vaccination information. The following ADT trigger messages are accepted: A01, A02, A03, A04, A05, A06, A07, A08, A09, A10, A14, A15, A16, A28, and A31. These messages add or update a patient record in the registry.

It is important to know that an ADT message is not required to register a patient in the registry. A VXU message without immunizations is sufficient. The ADT is accepted to allow hospital systems to register patients using a standard ADT message. Senders may choose to send ADT or VXU messages to register patients.

Observation Result (ORU)

The ORU message is a generic lab reporting message that is used by labs to report on the status of lab work. PHC Hub accepts lab messages for two different situations:

To receive lab data with lead test results
To receive immunization data from the GE Centricity EMR (Logician) via its LabLink interface in LinkLogic

Query for Patient Vaccination Query (VXQ or QBP)

The VXQ/QBP includes patient demographic data used by a registry to query another registry for a patient's vaccination record. When the IIS receives a query, it tries to match the patient data sent with patients in the registry and returns one of the following responses:

Message	Description
VXR(RSP)	Query response with patient vaccination record.
VXX(RSP)	Query response with multiple matches.
QCK	Query acknowledgement (no match).
ACK	Acknowledgment (indicates error). A negative ACK message is sent when an error prevents the completion of the request.

The standard for immunization messages does not allow the sender (the system originating the query) to specify how to do the patient query, but leaves it up to the receiving system to make that decision. Instead, the sender gives all known information about a particular patient and the receiving system must reply with exact or possible matches according to its own criteria.

PHC Hub finds matches as follows:

Search for a match by patient ID. If a match is found, return this patient. If the patient query is sent with:
- An MPI ID - The patient is queried by this ID and a shot record is returned
- The State Registry ID - The patient is queried by this ID and if found, a complete record is returned
- The sender's Medical Record Number - The patient's State Registry ID, including a prefix in a record entered manually via an IWeb user interface, is queried by this ID and if found, a complete record is returned
- The sender's Medical Record Number - The patient's Chart Number entered via an HL7 upload as a Medical Record Number is queried by this ID and if found, a complete record is returned
If no match was found in step 1, then the patient data is used to perform an advanced search which is a standard algorithm used by the main deduplication process to find exact and possible matches. The following fields are considered by the advanced search:
- Patient Last, First, Middle Name
- Patient Birth Date
- Patient SSN - Patient Medicaid Number
- Patient Birth Number
- Guardian First Name - Guardian SSN - Mother's Maiden Name
- Patient Address - Patient Phone
If no matches are found, the interface may be configured to run additional searches such as "first initial, last name, birth date" searches; however, only a few of these additional searches are normally configured since the advanced search is the best option. PHC Hub allows the administrator to configure each interface to have any set of optional queries included.
Once matching is complete, the following apply:
- If one exact match is found, this is returned in a VXR(RSP) message, which includes patient demographics and all immunizations
- If one or more matches is found, but some matches are possible, then a VXX(RSP) message is returned, which only includes the patient demographics for the possible matches
- If no match is found, then a QCK message is returned, to acknowledge the query and report that no matches were found
  
  The original CDC document specified that when there is one patient record match, the VXR(RSP) is returned; and if there are two or more matches found, then a VXX(RSP) is returned. This description assumed that all single matches would be good matches. For situations where there is only one match and it is not a good match, the IIS returns a VXX(RSP)
If the sending system gets a response that indicates a multiple match, it may display the demographic information and prompt the query user to choose one.
The sending system may then re-query with a message that includes the State Registry ID sent in the first response. This ensures an exact match on the second query and a return of an immunization record.