HL7 is represents "global standards for the exchange, management and integration of data that supports clinical patient care and the management, delivery and evaluation of healthcare services." It also stands for the (HL7) group that is a Designated Standards Maintenance Organization comprised of healthcare providers, software vendors and consultants.
The initial Version 2 of HL7 was message based and built more or less in an ad hoc manner.HL7 V2.x focused mainly on the "syntax" (structure and layout) for communication between systems.
The Version 3 is model-based built upon the Reference Information Model (RIM)
Version 3 is object-oriented (meaning that it combines data structures with functions to create re-usable objects).RIM is a unique representation of the health care domain set of information and data. RIM represents the semantic and lexical connections between the information carried in the fields of HL7 messages. RIM provides the basis for creating HIS application architecture and persistence layers. There is a RIM implementation based on Java that is available.
HL7 version 3 specifications37 for RIM include:
- Nouns--things that are being communicated
- Adjectives--descriptors and relationships of the nouns
- Verbs--actions being requested or communicated
- semantics of the communication--the actual meaning of a message
- syntax for communication--the structure and layout of the communication
- A channel to carry the communication
On a technical level, RIM is a collection of:
- Subject areas
- Classes--a template which defines the variables and methods for a particular type of object, example: patient class. Core RIM classes are Entity, Role, Participation, Act, Act-Relationship and Role-Link.
- Attributes--qualities of a class, for instance patient class would have name, date of birth, sex, address, etc.39
- Use cases--a way in which a system can be used, described as a step-by-step sequence of actions, along with the system's response and certain other information
- Actors--patients, medical and health professionals, and anyone else involved in a health care event
- Trigger events, example: follow-up clinical visit by a patient
Interactions
For clinical content needs, the HL7 vocabulary tables refer to external terminology sources like SNOMED, ICD10.
Detailed RIM tutorials @ are here
EHR, itself being a repository if information, does not have a standard. But HL7 drafted a functional model for EHR systems. The model helps create functional profiles. The profiles are listed below
Direct Care Profile
- Care Management
- Clinical Decision Support
- Operations Management and Communication
Supportive Profile
- Clinical Support
- Measurement, Analysis, Reporting, Research
- Administrative and Financial
Information Infrastructure Profile
- EHR Security
- EHR Information and Records Management
- Unique Identity, Registry and Directory services
- Support for HIT standards
- Interoperability
- Manage Business Rules
- Workflows
In total there are about 125 functions each with a function name, function statement, description and rationale for inclusion.
The clinical domains include
– Laboratory, Radiology, Nursing, Surgery, Pharmacy, Dietary
Administrative domains include…
– Registration, Billing, Scheduling, Medical records, Staff demographics
– Authorization and permissions
In an effort to create a Healthcare Business Process Reference Model, we can use the HL7 Healthcare Development Framework's practices. One practice that interested me in particular is the Domain Analysis. The diagram below gives the structure of accomplishing a typical domain analysis.
In summary, there is much to be leveraged from HL7 artifacts but finding what is relevant in an ocean of artifacts is a challenge :-).
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