Part I - Transform custom healthcare messages to HL7

EHR (Electronic Health Record) systems are designed in a proprietary format/structure and are not based on such market models as FHIR or HL7. Whereas some of those systems can interoperate data in a proprietary format for FHIR and further market models, others cannot. InterSystems has two platforms that can interoperate proprietary formats for market standards: InterSystems HealthShare Connect and InterSystems IRIS for Health. The transformation functionality (DTL - Data Transformation Language) of these platforms can receive data in any format, structure, or communication channel (CSV, JSON, XML, and others via FTP, File, HTTP, etc.) and transform it into market formats directly (FHIR, CDA, HL7 and so on).
This article is divided into two parts. The first one is dedicated to talking about HL7. In part II, on the other hand, we will show you how to transform proprietary/custom data into HL7 using IRIS for Health. The sample data we used for our experiment was taken from the SYNTHEA bulk data generation project (https://synthea.mitre.org/downloads). So, in our example, we will convert 1000 patients from a CSV file to HL7 v2, using the Interoperability features of IRIS for Health.

About HL7 Organization

The Health Level Seven International®, or HL7, is a member-driven non-profit organization dedicated to creating and maintaining standards that bridge the gap between various healthcare technologies. Founded in 1987, it is an ANSI-accredited standards-developing organization that provides a comprehensive framework and related standards for exchanging, integrating, sharing, and retrieving electronic health information that supports clinical practice as well as management, delivery, and evaluation of health services. One of the most popular standards developed by this organization is the HL7 standard in version 2.

About HL7 standard, version 2

HL7’s Version 2.x (V2) messaging standard is the workhorse of electronic data exchange in the clinical domain and is arguably the most widely implemented standard for healthcare in the world. This messaging standard allows the exchange of clinical data between systems. It is designed to support a central patient care system as well as a more distributed environment where data resides in departmental systems (see more on https://www.hl7.org/implement/standards/product_brief.cfm?product_id=185).Whereas the newest version 2 is 2.9, the most used one is 2.3. So, let's focus on getting more understanding about that version. The HL7 v2 standard specifies data exchange (messages) for each possible business process (ADT events - Admit, Discharge, and Transfer) that may occur in EMR solutions. Take a look at the table below:

The events type list
Code    Event Description
A01    Admit/visit notification
A02    Transfer a patient
A03    Discharge/end visit
A04    Register a patient
A05    Pre-admit a patient
A06    Change an outpatient to an inpatient
A07    Change an inpatient to an outpatient
A08    Update patient information
A09    Patient departing - tracking
A10    Patient arriving - tracking
A11    Cancel admit/visit notification
A12    Cancel transfer
A13    Cancel discharge/end visit
A14    Pending admit
A15    Pending transfer
A16    Pending discharge
A17    Swap patients
A18    Merge patient information
A19    Patient query
A20    Bed status update
A21    Patient goes on a leave of absence
A22    Patient returns from a leave of absence
A23    Delete a patient record
A24    Link patient information
A25    Cancel pending discharge
A26    Cancel pending transfer
A27    Cancel pending admit
A28    Add person’s information
A29    Delete person’s information
A30    Merge person’s information
A31    Update person’s information
A32    Cancel patient arriving - tracking
A33    Cancel patient departing - tracking
A34    Merge patient information - patient ID only
A35    Merge patient information - account number only
A36    Merge patient information - patient ID and account number
A37    Unlink patient information
A38    Cancel pre-admit
A39    Merge person - patient ID
A40    Merge patient - patient identifier list
A41    Merge account - patient account number
A42    Merge visit - visit number
A43    Move patient information - patient identifier list
A44    Move account information - patient account number
A45    Move visit information - visit number
A46    Change patient ID
A47    Change patient identifier list
A48    Change alternate patient ID
A49    Change patient account number
A50    Change visit number
A51    Change alternate visit ID
A52    Cancel leave of absence for a patient
A53    Cancel patient returns from a leave of absence
A54    Change attending doctor
A55    Cancel change attending doctor
A60    Update allergy information
A61    Change consulting doctor
A62    Cancel change consulting doctor

The HL7 specification details each ADT event on segments.The most used event is the A01 which is intended to be used for “Admitted” patients only. This event is sent as a result of a patient undergoing the admission process that assigns the patient to a bed. It signals the beginning of a patient’s stay in a healthcare facility. Usually, this information is entered into the primary Patient Administration system and broadcasted to the nursing units and ancillary systems. It includes short stay and John Doe admissions. For instance, we can use an A01 event to notify: the pharmacy system that a patient has been admitted and may be prescribed drugs legitimately; the nursing system that the patient has been received and needs a care plan prepared; the finance system of the start of the billing period; the dietary system that a new patient has been installed and requires dietary services; the laboratory, pathology, and radiology systems that a patient has been admitted and is entitled to receive these services; the clinical repository that admission has taken place for the EMR (electronic medical record).

Details for sending an A01 event

In most HL7 messages, the pipe character |, also called Vertical Bar, is the pipe separator field, so in the case of our message, we will use the ^ as a space. When you come across multiple pipes together (like these ones ||||||||||), it means that the fields in these sequences are optional or not included. Also, remember that segments are separated by a CR – Carriage Return.

The MSH segment sample

MSH|^~\&|EPICADT|DH|LABADT|DH|201301011226||ADT^A01|HL7MSG00001|P|2.3|

The EVN segment sample

EVN|A01|201301011223||

The PID segment sample

PID|||MRN12345^5^M11||APPLESEED^JOHN^A^III||19710101|M||C|1^CATALYZE
STREET^^MADISON^WI^53005-1020|GL| (414)379-1212|(414)271-
3434||S||MRN12345001^2^M10|123456789|987654^NC|

The NK1 segment

NK1|1|APPLESEED^BARBARA^J|WIFE||||||NK^NEXT OF KIN

The PV1 segment

PV1|1|I|2000^2012^01||||004777^GOOD^SIDNEY^J.|||SUR||||ADM|A0|

The complete sample

MSH|^~\&|EPICADT|DH|LABADT|DH|201301011226||ADT^A01|HL7MSG00001|P|2.3|
EVN|A01|201301011223||
PID|||MRN12345^5^M11||APPLESEED^JOHN^A^III||19710101|M||C|1 CATALYZE
STREET^^MADISON^WI^53005-1020|GL|(414)379-1212|(414)271-
3434||S||MRN12345001^2^M10|123456789|987654^NC|
NK1|1|APPLESEED^BARBARA^J|WIFE||||||NK^NEXT OF KIN
PV1|1|I|2000^2012^01||||004777^GOOD^SIDNEY^J.|||SUR||||ADM|A0|

• For more samples, visit the following website: https://confluence.hl7.org/display/OO/v2+Sample+Messages
• For more details about the ADTs, proceed to the next link: https://interopera.esy.es/wp-content/uploads/2017/04/HL7-PRIME-Mensagens... and https://hl7-definition.caristix.com/v2/HL7v2.3.1/TriggerEvents/ADT_A01.

Bonus: use IRIS to learn more about HL7 messages

To know more about HL7 messages, segments, and fields, go to any IRIS for Health or HealthConnect instance and select Interoperability > Interoperate > HL7 v2.x. Then click HL7 v2.x Schema Structures:

On HL7 Schemas click 2.3.1:

You can navigate on message types and study everything you find there. Click ADT_A01 to see its segments:

Double-click the PID segment and skim through the field’s documentation:

In part II, we will create an IRIS for Health instance and build a sample. Thanks for reading.