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SNOMED

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CT HL7 IPS Free Set

In 2019, SNOMED International and Health Level Seven International (HL7) HL7 International announced the formalization of a license agreement in which a relevant "Free for Use" Set of SNOMED CT coded concepts will be used within the HL7 International Patient Summary (HL7 IPS). HL7 is a not-for-profit, ANSI-accredited standards standard developing organization dedicated to providing a comprehensive framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information that supports clinical practice and the management, delivery, and evaluation of health services. The HL7 IPS is a minimal and non-exhaustive patient summary dataset, specialty-agnostic, and condition-independent, but readily usable by clinicians for the cross-border unscheduled care of a patient. The collaboration is consistent with the aims of both organizations to support international harmonization. 

The SNOMED CT International Patient Summary (IPS) is international in scope and in addition to harmonization with HL7 IPS, is aligned with CEN's European Standard for the Patient Summary. The IPS free set consists of more than 8,000 SNOMED CT terms for use in implementations of the HL7 CDA R2 and FHIR IPS Implementation Guides worldwide. The SNOMED CT HL7 IPS free set contains concepts that can record the following data:

  • General information about the patient (e.g., gender)
  • Medical summary of most important clinical data (e.g., allergies, current medical problems, major surgical procedures)
  • A list of current medications

The HL7 IPS Free Set is available for non-Member Affiliates as a plain list of concepts and their descriptions, supporting the use case of data exchange, but lacking all the capabilities provided by the SNOMED CT ontology, available only to members in complete SNOMED CT relaeses.The SNOMED CT IPS RF2 refset is available from SNOMED International and affiliates directly from HL7, and as part of the Global Patient Set a package that collects different free sets released by SNOMED International,  these releases consists of a list of concept identifiers, fully specified names, preferred terms (in international English) and active/inactive status flags. The HL7 IPS Free Set is designed to support data sharing. However, it lacks the additional capabilities of the SNOMED CT terminology, which is available via a full SNOMED CT release. The HL7 IPS Free Set is also available for Members and Affiliates as a reference set, distributed in a RF2 release package via a National Release Center or the international MLDS service. This reference set is maintained and updated annually, in line with the latest July SNOMED CT International Release.

Access within SNOMED International member countries is provided by the Member National Release Centre in each country, via the relevant Member page. Affiliates of SNOMED International in non-member countries can access the refset through their Member Licensing and Distribution SERVICE (MLDS) account. Please contact info@snomed.org for more information if required.

SNOMED International IPS Terminology

For more information, please contact info@snomed.org.

IPS Terminology

SNOMED International's The SNOMED International IPS Terminology represents an evolution of the HL7 IPS Free Set, adding the relationships that transform this content into providing advanced terminology features for non-affiliates to use in their IPS solutions. In particular, it adds a hierarchy, defining relationships and extra synonyms from the SNOMED CT international edition, to form a sub-ontology of SNOMED CT.   A sub-ontology is a functional set of concepts and relationships extracted from the full SNOMED CT Ontology, providing new ontology that provides the following features:

  • It can be loaded in a SNOMED CT compatible terminology server
  • It includes all the active concepts from the HL7 IPS Free Set
  • The concepts are The content is organized into the same hierarchies present in as the complete SNOMED CT International Edition (ie.eg., Clinical Findings, Procedures, etc)
  • The content is expanded to include a small minimal set of additional grouper concepts, the minimum necessary to construct the SNOMED CT hierarchy structures
  • The content also includes (inferred) relationships that define the meaning of the included concepts
  • The US-English and GB-English language reference sets are included just like in the complete International Edition
  • It's possible to run ECL (Expression Constraint Language) queries can be executed over the IPS Terminology content to support terminology binding value set definitions and simple data analyticsAll these features are limited to the reduced content in

Please note that the IPS Terminology

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contains only a subset of the full international release of SNOMED

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CT, and therefore the features above are limited to this restricted content.

The IPS Terminology is made available as an RF2 package , with a similar format to any other SNOMED CT Edition package. The releases. However, the package is not fully RF2 compatible, the content is available only available in "snapshot" format (including only the last i.e. the current state of each component), and it includes only includes components that are active components at the moment of the terminology extraction. The time the terminology is extracted. The relationship ids are published using temporary ids. Each IPS Terminology release replaces the previous one, providing a new snapshot of active content; it's not designed for incremental updates.

The IPS Terminology package does not include historical information , (which is normally available to licensed affiliates Affiliates in the full SNOMED CT releasereleases).

The RF2 package of the IPS Terminology package can be loaded into any compatible terminology server and can be navigated with terminology browsersinto SNOMED International's Snowstorm, a freely available, open-source terminology server maintained by SNOMED International. SNOMED International provides a browser for the IPS Terminology in: https://iaa.snomed.tools/?perspective=full&conceptId1=138875005&edition=MAIN/SNOMEDCT-IPS-TEST2&release=&languages=en

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IPS Terminology.

Feature Comparison

The IPS Terminology is a subset of the SNOMED CT International Edition. It is designed to provide the necessary terminology features for a simple IPS implementation. It has more features than the IPS Free Set, but less than a complete SNOMED CT edition. A complete SNOMED CT edition provides advanced features to improve the capabilities of an implementation.

The table below provides a high-level comparison of the key features of each type of terminology resource.

Feature

IPS Free Set

IPS Terminology

SNOMED CT International Edition

Concepts8,000+15,000+354,000+
Descriptions16,000+ (FSN and preferred synonym)

42,000+ (all types)

1,276,000+ (all types)
RelationshipsNo40,000+1,215,000+
HierarchiesNoYes, limitedYes, all
ECL supportNoYesYes
Stated axiomsNoNoYes
Module dependencyNoNoYes
History mechanismsNoNoYes
RF2 formatNoActive Snapshot onlyFull, Snapshot, Delta (computable)
Terminology server useNoYesYes
Postcoordination supportNoNoYes
Extension supportNoNoYes

Example of Use

The HL7 FHIR IPS Implementation guide specifies the terminology binding for each of the coded data elements within the IPS components, for composition. For example, the "Procedures" value set (http://hl7.org/fhir/uv/ips/ValueSet-procedures-uv-ips.html), that -IPS value set defines the valid codes values for the "Procedures" resource in the IPS composition (http://hl7.org/fhir/uv/ips/StructureDefinition-Procedure-uv-ips.html), specifies a logical definition with inclusion and exclusion clauses as follows:'code' data element in the Procedures resource. The Procedures-IPS value set is defined using a logical definition, consisting of the following inclusion and exclusion clauses.

Using the IPS Terminology installed in a terminology server it's possible to create an ECL expression that This logical definition is equivalent to this FHIR logical definition in order to support the extraction of the exact list of concepts that are included the following SNOMED CT Expression Constraint (ECL) query, which can be executed against any full edition of SNOMED CT to extract the list of concepts to include in this value set:.


Scg expression
((< 71388002 |Procedure (procedure)|)
   MINUS (< 14734007 |Administrative procedure (procedure)|
       OR < 59524001 |Blood bank procedure (procedure)|
       OR < 389067005 |Community health procedure (procedure)|
       OR < 442006003 |Determination of information related to transfusion (procedure)|
       OR < 225288009 |Environmental care procedure (procedure)|
       OR < 308335008 |Patient encounter procedure (procedure)|
       OR < 710135002 |Promotion (procedure)|
       OR < 389084004 |Staff related procedure (procedure)|))|)




When using the IPS Terminology for recording and sharing IPS data, it may be necessary to simplify these terminology bindings to ensure that only codes included in the IPS Terminology are referenced by the ECL query. For this example, the following query (which refers only to concepts contained in the IPS Terminology) can be used to extract the list of IPS Terminology concepts to include in this value set.


Scg expression
< 71388002 |Procedure|
   ANDMINUS (^816080008 |International Patient Summary< 14734007 |Administrative procedure|
       OR < 308335008 |Patient encounter procedure|)



This ECL expression can be submitted to a terminology server through its API and (on which the IPS Terminology content will be filtered for this specific use case, identifying a procedure, returning only the valid concepts for this purpose. It was not possible to perform these constraint operations with the IPS Free Set, it has been installed), via a standard HL7 FHIR Terminology Services API, to extract the SNOMED CT concepts that may be used in the Procedures-IPS value set. This capability is available in all standard SNOMED CT Releases, but it was not previously possible with the HL7 IPS Free Set. However, this has been enabled by the sub-ontology structure and features. The ECL Expressions also facilitate updating to new releases of the IPS Terminology or to adopting a complete release of SNOMED CT, and the resulting set will be computed in real time from the available contentnew features of the IPS Terminology. Using ECL expressions in this way, implementers can update their value sets with each new release of the IPS Terminology.