HL7 CRM Messages: Clinical Study Registration Message

HL7 CRM messages register a patient into a clinical study or trial, or update their enrollment status. A CRM message is sent from the clinical trials management system (CTMS) or coordinating application to the patient care system (such as an EHR) to notify other providers that the patient has enrolled in a specific clinical trial, entered a new study phase, or completed their participation. This page explains what a CRM message represents, the trigger events that carry it, every segment the message can contain and what each one holds, and how a CRM registration relates to FHIR. Sample content is constructed for illustration with fictional identifiers.

What a CRM message represents

A CRM message — CRM stands for Clinical Study Registration — communicates a patient's enrollment and status within a structured clinical study. The core of the message is the CSR segment (Clinical Study Registration), which carries the unique study identifier, the patient's assigned subject number, enrollment dates, and active study status. An optional CSP segment (Clinical Study Phase) identifies the specific phase of the trial the patient is currently entering (e.g., screening, active treatment, or follow-up).

The sender is the clinical trial management system (CTMS) or research database, and the receiver is the EHR or clinical repository that stores the patient's master record. CRM is critical for patient safety: it flags the patient's chart with trial details, ensuring that other clinicians are aware of experimental drug therapies or restricted clinical procedures.

When a CRM message is sent

A CRM message is sent at major milestones in a patient's study lifecycle. Common triggers include:

• A clinical trial coordinator registers a patient into a new trial, sending a CRM^C01.
• A patient transitions from the screening phase to the active intervention phase, triggering a CRM^C02 update.
• A patient completes their final follow-up visit and is discharged from the trial, triggering an status update.

Trigger events

The CRM message type supports several trigger events, including:

• CRM^C01 – Register a patient on a clinical study.
• CRM^C02 – Update a patient's clinical study registration.

Receivers use MSH-9 to determine the operation: C01 creates the research subject record, and C02 updates the patient's study status or phase.

Integration topology

The diagram shows the clinical trial management system (CTMS) registering a patient through the integration engine into the clinical EHR system.

{{diagram: clinical trial system (CTMS) → CRM message → integration engine → clinical EHR}}

Typical senders: clinical trial management system (CTMS), research study database, EDC (Electronic Data Capture) platform.

Typical receivers: EHR, clinical repository, master patient index (to flag research status).

Direction: unidirectional notification from the research system to the patient care systems.

Segments in a CRM message

The CRM message is organized into a header block followed by patient details and the study-specific segments CSR and CSP. Cardinality follows HL7 notation: [X] optional, {X} repeating, [{X}] optional and repeating; a bare code is required. Each segment code links to its canonical field-by-field reference.

[ ] = optional, { } = repeating

Sample CRM message

Note. Constructed for illustration. Study identifiers, patient identifiers, and names are fictional.

MSH|^~&|CTMS|MERCY|EHRSYS|MERCY|20260604090000||CRM^C01^CRM_C01|MSG00048|P|2.5.1
PID|1||MR98765^^^MERCY^MR||SMITH^PATRICIA^A||19720315|F
PV1|1|I|3N^301^A^MERCY
CSR|STUDY-8831^Diabetes Trial Phase II^L|SUBJ-1200^Subject 1200^L|20260604090000|20260604090000|||AC^Active^HL70305
CSP|PHASE-1^Screening Phase^L|20260604090000|AC^Active^HL70305

What this sample shows

The CRM^C01 in MSH-9 marks a clinical study registration. PID carries the patient identifier MR98765 and name. PV1 links the enrollment to encounter location 3N-301-A. The CSR segment registers the patient: study ID STUDY-8831 (Diabetes Trial Phase II) in CSR-1, subject identifier SUBJ-1200 in CSR-2, enrollment date 20260604090000 in CSR-3, and status Active in CSR-8. The CSP segment places the patient in the Screening Phase starting on the same date.

Working with CRM messages

Reconcile Patient and Subject Identifiers

A patient in a clinical trial has a medical record number (PID-3) and a separate study-specific subject identifier (CSR-2). Receiving applications must record both identifiers, maintaining the linkage so that clinical data or observations collected during the trial are routed to the correct patient chart while preserving anonymity in research exports.

Manage Study Lifecycle Statuses

CSR-8 carries the patient's enrollment status (Active, Complete, Withdrawn). Use these status changes to toggle research flags on the patient's chart. When a patient withdraws, their status should immediately update to inactive to ensure they are excluded from further trial-specific clinical protocols or automated alerts.

Vendor variance. Systems differ in how they communicate study phases. Some systems include all phases in repeating CSP segments within a single CRM update; others send a new CRM^C02 message every time the patient transitions to a new phase. Verify PIS capabilities to prevent overwriting historical phase dates.

FHIR equivalent

A clinical study registration corresponds to the FHIR ResearchSubject resource, which links a Patient resource to a ResearchStudy resource.

The HL7 v2-to-FHIR Implementation Guide publishes no message map for CRM_C01 and no ConceptMap for the study segments (CSR/CSP). Consequently, any FHIR translation must be mapped manually, creating a ResearchSubject resource with status derived from CSR-8, referencing the Patient from PID and the ResearchStudy from CSR-1.

Common pitfalls

Pitfall. Keying on the study identifier instead of the subject identifier. CSR-1 identifies the trial protocol, while CSR-2 is the patient's unique research enrollment key. Conflating them will corrupt patient study flags in the EHR.

Pitfall. Discarding CSP phase start dates. Dropping phase timestamps prevents researchers from accurately tracking the timeline of patient events during data analysis.

How Vorro handles CRM messages

Vorro ingests CRM messages over MLLP, validates the study identifiers in CSR and CSP, and updates the corresponding patient record flags in the EHR. Vorro maintains the mapping between the clinical patient ID and the research subject ID. Where a FHIR destination is configured, Vorro maps the registration to a FHIR ResearchSubject resource manually, since the HL7 v2-to-FHIR guide provides no published map for this message.

Related messages

• CSU — the clinical study unsolicited data message.
• CQU — the clinical study data query message.
• ADT — the admission, discharge, and transfer message.

Sources

• HL7 v2-to-FHIR IG — message maps index
• HL7 Messaging Standard Version 2.5.1 product brief