HL7 Version 3 Veli BICER

Agenda HL7 Problems with Version 2.x HL7 Models Use Case Model Information Model Interaction Model Message Model

HL7 founded in 1987 To provide standards for the exchange, management and integration of data that supports clinical patient care and the management, delivery and evaluation of healthcare services.

Problems with version 2.x Problem: misunderstanding of specifications Result: Different implicit information models Problem: Misleading conformance claims Result: No vocabulary to describe conformance concepts

Problems with version 2.x Implicit information model, not explicit Need for controlled vocabularies No explicit support for object technologies No explicit support for security functions Optionality is ubiquitous and troublesome

Contents of HL7 V2.3 Trigger events –Actions or occurrences Messages –Information content Segments –Repeating structures Data elements –Data representation

HL7 Version 3.X Specification Version 3 Methodology - MDF Conformance Claims to improve the internal consistency of HL7

HL7 Models A model is a collection of subject areas, scenarios, classes, attributes, use cases, actors, trigger events, interactions, etc. that depict the information needed to specify HL7 Version3 messages. HL7 models are further divided into four specific models - a use case model, an information model, an interaction model, and a message design model.

HL7 Models

Use Case Model

Describes specific situations in which communication between healthcare entities is needed.

Information Model

A detailed and precise definition for the information from which all data content of HL7 messages are drawn. Classes, Attributes, and Relationships –Documented in the Reference Information Model, the Domain Information Model, and the Message Information Model State Transition Models for certain selected classes. Data Types and Constraints.

Reference Information Model (RIM) Root of all information models. Provides a static view of the information. A HL7-wide common reference model that integrates all Technical Committees’ domain views. Committees and SIGs generally work with a small subset of the RIM - called Domain Information Model or DIM.

Reference Information Model (RIM) Foundation Classes –Acts –Entities –Roles Communication Infrastructure –Core Infrastructure –Message Communications Control –Structured Documents

Reference Information Model (RIM)

Interaction Model

Specifies all Trigger Events and Message Flows. Specifies the Application Roles.

Interaction Model Each Interaction consists of: –Trigger event Initiators of Interactions. –Message ID Each interaction sends one particular message –Sender role When trigger event detected, message is sent –Receiver role Receiver responsibility

Interaction Model Application Role - identifies an information management responsibility for one of the subject classes. Responsibilities typically are: Creator, Manager, Tracker and Archivist. Healthcare applications are assumed to take on one or more application roles. Interaction

Interaction Model

Message Model

Message Specification Domain Information Model Message Information Model Reference Information Model Interaction Model Hierarchical Message Description Use Case Model

Subset the RIM  MIM The RIM must first be refined by subsetting and constraining it –Create a MIM with RIM classes needed –Develop an R-MIM from these classes Collection of classes with some constraints Collection of attributes and associations to support the R-MIM

RIM content MIM content (a proper subset of the RIM) Fewer attributes

Convert the MIM  R-MIM Constrain cardinality on Associations Constraints on Attributes –Some may be left out –Sub-components may be individually constrained Classes are duplicated for different uses May modify the Inheritance structure –Some specializations may subsume the generalization –Always inherit downwards to specializations

MIM

RMIM

a 4 5 3

Implementation Technology Specification A method of encoding and sending HL7 messages. XML represents one of several ITS to be developed

An HL7 V2.3 Message MSH|^~\&|LABGL1||DMCRES|| ||ORU^R01|LABGL |P|2.3 |||NE|NE PID||| ^Y^C8||Newman^Alfred^E|| |M||W|25 Centscheap Ave^^ Whatmeworry^UT^85201^^P||(555) |(444) ||M|| OBR||110801^LABGL| ^DMCRES| ^CELL COUNTS+DIFFERENTIAL TESTS (COMPOSITE)^LN||| ||35^ML|||||||IN2973^Schadow^Gunther^^^^MD^UPIN ||||||||||^Once||||||CA20837^Spinosa^John^^^^MD^UPIN OBX||NM|4544-3^HEMATOCRIT (AUTOMATED)^LN||45||39-49 |||| F||| ||CA20837 OBX||NM|789-8^ERYTHROCYTES COUNT (AUTOMATED)^LN||4.94|10*12/mm3 | ||||F||| ||CA20837

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