HL7 QBP_Q23 Get Corresponding Identifiers

Ask an identity source which identifiers belong to the same person.
HL7 message structure QBP_Q21 groups and segments from HL7 v2.5.1 Hide structure

These are the generated groups and segments for the version selected at the top of the page. The article explains the workflow, and this panel follows the chosen HL7 version.

Message Structure

SegmentNameRequiredRepeatable
MSH
 Message Header Yes No
SFT
 Software Segment No Yes
QPD
 Query Parameter Definition Yes No
RCP
 Response Control Parameter Yes No
DSC
 Continuation Pointer No No

QBP_Q23 is a corresponding-identifiers query. A requester has one patient identifier and asks an MPI or identity cross-reference manager for equivalent identifiers in other domains. This is the HL7 v2 shape behind many PIX-style workflows.

The trigger is Q23, but the shared structure is commonly expressed as QBP^Q23^QBP_Q21. The generated panel below shows QBP_Q21 because this local reference data uses the shared QBP query structure for Q21 through Q25-style identity queries.

A small QBP Q23 example

MSH|^~\&|EHR|CITYHOSP|MPI|CITYHOSP|20260717101000||QBP^Q23^QBP_Q21|QBP230001|P|2.5.1 QPD|Q23^Get Corresponding Identifiers^HL7nnn|Q230001|123456^^^CITYHOSP&1.2.3&ISO^MR|SOUTHLAB&2.16.840.1&ISO RCP|I|10^RD

What workflow it represents

The sender is often an EHR, portal, lab, radiology system, or integration engine that needs the receiver's identifier before it can request, route, or file data. The receiver is usually an MPI or cross-reference manager that knows which identifiers belong to the same person.

The usual response is RSP_K23, where PID-3 returns the corresponding identifiers. In a PIX-style exchange, the assigning authorities must be fully qualified so every returned identifier can be traced back to the correct domain.

How to read the structure

The query uses the same compact QBP structure as the neighboring demographics queries: MSH, QPD, RCP, and optional DSC. The difference is the meaning of the QPD parameters. One parameter identifies the known patient ID, and another can identify which domains the requester wants back.

Do not strip the assigning authority subcomponents out of the CX values. In cross-reference work, the authority is the difference between "this identifier" and "this identifier in the only domain that makes it meaningful."

Implementation traps

The common failure is returning an identifier without enough authority detail. That may pass a string comparison in a test environment and still fail when two sites issue similar numbers. Use namespace ID, universal ID, and universal ID type when the profile requires them.

Also agree whether a no-match response is a normal query outcome or an operational error. A clean no-match should not look the same as a rejected query, a bad assigning authority, or a receiver outage.

Reference notes

IHE PIX Query uses QBP^Q23 with RSP^K23 to request corresponding identifiers, and emphasizes fully qualified assigning authorities in returned identifiers. See IHE ITI-9. Public HL7 v2 query tables also list Q23 under the shared QBP_Q21 structure family.