ADT^A28 — Add Person Information

Creates an MPI identity without an appointment, admission or active encounter. A28 is the pure registration event, distinct from A04 (Register outpatient) and A01.

Purpose

A28 propagates a new identity from a Master Patient Index (MPI) to consumer systems. Typical cases: pre-creation from an online registration module, import of an external patient file (record transfer from another facility), preventive creation ahead of a future appointment.

A28 has NO mandatory PV1 — there is no (yet) associated visit. PD1 (Patient Additional Demographics) and NK1 (Next of Kin) may enrich the identity at creation time.

Segment structure

Structure ADT_A05 shared with A05/A14/A31. MSH, EVN, PID, PD1 (optional), NK1 repeatable.

Real-world example

Creation of a new identity NGUYEN Tran from web registration:

MSH|^~\&|MPI|HOSP01|EHR|CLINIC02|20260516170000||ADT^A28^ADT_A05|MSG00028001|P|2.5.1|||AL|NE
EVN|A28|20260516170000|||REG001^Registrar^John^^^MS.|NEW PERSON REGISTRATION
PID|1||NEW100001^^^HOSP^MR||NGUYEN^TRAN^^^MR.||19900812|M|||78 RUE DU BAC^^PARIS^^75007^FRA||+33145678901
PD1|||CABINET DR LEFEVRE^^L0042
NK1|1|NGUYEN^MAI^^^MS.|SPO

Acknowledgment (ACK)

MSH|^~\&|EHR|CLINIC02|MPI|HOSP01|20260516170001||ACK^A28^ACK|ACK00028001|P|2.5.1
MSA|AA|MSG00028001

Common errors

• A28 with PV1: semantic contradiction. If a visit exists, use A04 or A01 depending on context.
• MPI duplicate: A28 without probabilistic matching check creates duplicates. To be cleaned up later via A18/A40.
• No typed PID-3: MRN identifier without qualifier — receiver does not know whether it is the local MR, the NHS Number, the INS-NIR.

Related ADT events

See also: ADT^A04, FHIR Patient.