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© International Health Terminology Standards Development Organisation 2016. All rights reserved.   SNOMED CT® was originally created by The College of American Pathologists.

This document forms part of the SNOMED CT to GP-FP and ICPC-2 map Edition Production release of SNOMED CT® distributed by International Health Terminology Standards Development Organisation (IHTSDO), which is subject to IHTSDO’s SNOMED CT® Affiliate License, details of which may be found at http://www.ihtsdo.org/snomed-ct/get-snomed-ct/.

No part of this document may be reproduced or transmitted in any form or by any means, or stored in any kind of retrieval system, except by an Affiliate of IHTSDO in accordance with the SNOMED CT® Affiliate License. Any modification of this document (including without limitation the removal or modification of this notice) is prohibited without the express written permission of IHTSDO.

Any copy of this document that is not obtained directly from IHTSDO [or a Member of IHTSDO] is not controlled by IHTSDO, and may have been modified and may be out of date. Any recipient of this document who has received it by other means is encouraged to obtain a copy directly from IHTSDO [or a Member of IHTSDO. Details of the Members of IHTSDO may be found at http://www.ihtsdo.org/members/].

Access to the SNOMED CT to ICPC-2 map is provided through a collaboration agreement between WONCA and IHTSDO. 

Access within IHTSDO member countries is provided by the national release centre in each country, via the relevant Member page(linked). Affiliates of IHTSDO in non-member countries can access the map through their MLDS account. Please contact info@ihtsdo.org for more information if required.

Users of the map MUST comply with the licensing agreements of both ICPC-2 and SNOMED CT.

Table of Contents

1 Introduction

The SNOMED CT International General/Family Practice Reasons for encounter and/or Health issues subset set (hereafter called the GP/FP Subset) and the map from the GP/FP Subset to the International Classification of Primary Care (ICPC-2) were both developed between 2010 and 2013 by the GP/FP Subset and ICPC mapping project group. This project ended on December 31, 2013 after field-testing of the products was completed. 

2 Background

In December 2009 a harmonization agreement was finalized between the IHTSDO and the World Organization of Family Doctors (Wonca) to promote co-operation and collaboration between the two organizations. 

This agreement led to the formation of the International Family Physician/General Practitioner Special Interest Group (IFP/GP SIG) under the auspices of the IHTSDO. The IFP/GP SIG was established to suggest content for the Systematized Nomenclature of Medicine – Clinical Terms (SNOMED CT®) related to general/family practice and to provide quality assurance for SNOMED CT content from the general/family practice perspective. The IHTSDO's existing Primary Care Special Interest Group was converted to the IFP/GP SIG after the agreement was signed. 

The agreement contained a commitment to develop a mapping program, mapping relevant content in SNOMED CT to the International Classification of Primary Care, Version 2 (ICPC-2). Under the terms of the agreement, each task or project in the mapping program was to be managed by a mapping project group, comprised of members from the IFP/GP SIG, the WONCA International Classification Committee (WICC) and the IHTSDO's Mapping Special Interest Group. This project group was established in early 2010 and called the 'International GP/FP subset and ICPC mapping project group'. 

The subsets were first released as a candidate baseline in April 2014. Changes to the structure of the subsets were made following feedback from this release. 

 

3 Release content

 3.1 Overview of the GP/FP subset

Note: This document provides release information about the GP/FP subset. Release information about the map from the GP/FP subset to ICPC-2 can be found in the document SNOMED CT to ICPC-2 mapping: Release notes. 
The GP/FP subset contains SNOMED CT concepts relating to two semantic data types commonly used in general/family practice electronic health records:

• Reasons For Encounter (RFEs)

• Health Issues.

A reason for encounter was defined as:
"An agreed statement of the reason(s) why a person enters the health care system, representing the demand for care by that person. The terms written down and later classified by the provider clarify the reason for encounter and consequently the patient's demand for care without interpreting it in the form of a diagnosis. The reason for encounter should be recognized by the patient as an acceptable description of the demand for care" (WONCA Dictionary of General/Family Practice, 2003). 
A health issue was defined as an:
"Issue related to the health of a subject of care, as identified or stated by a specific health care party". This is further defined in the notes as "according to this definition, a health issue can correspond to a health problem, a disease, an illness" (Health informatics – System of concepts to support continuity of care – Part 1: basic concepts (CEN/ISO FDIS 13940-1)). 
These definitions were used to define the scope of the GP/FP subset. The subset contains SNOMED CT concepts that represent terms commonly used to populate these semantic data types. 
The content of the subset covers the following:

• Symptoms and signs

• Disorders and diseases

• Results

• Family history

• Allergies

• Adverse drug reactions

• Processes and procedures

• Social history.

Information about implementation of the subset can be found in Section 4. 
Details on the development of the subset are available on request from info@ihtsdo.org

4 Implementation of the GP/FP Subset

 4.1 Implementation overview

There are a variety of ways in which the GP/FP subset and map to ICPC-2 can be implemented, and it would be impossible to outline each possible scenario in this report. Vendors are encouraged to contact members of the IFP/GP SIG to discuss specific implementation scenarios. 

4.2 General information about the GP/FP subset

Subsets act as the extensibility mechanism in SNOMED CT, allowing developers and users to customize SNOMED CT content to meet specific use cases. 
Content for the general/family practice subset is provided by the IHTSDO's General/Family Practice and ICPC-2 mapping project group. It is designed for use in general/family practice clinical settings within electronic health records (EHRs). It is intended for use as the 'core' subset for two commonly used data fields — reasons for encounter and health issues. 

The subset is aligned to the January 2016 SNOMED CT International Release. 

4.3 Purpose of the GP/FP subset

To provide a subset of frequently used SNOMED CT concepts for use in general/family practice EHRs within the following data fields:

• Reason for encounter

• Health issue

4.4 Some example use cases of the GP/FP subset

 4.4.1 Data entry – direct entry of SNOMED CT concepts from the GP/FP subset

During an encounter in his/her general/family practice, a GP/FP sees a patient who has presented with a newly identified health issue. The GP/FP enters the new health issue into the data field for 'health issue', and into a problem list (if appropriate) in his/her EHR using the GP/FP subset that has been incorporated in his/her EHR by the EHR software vendor. The GP/FP is presented with a validated list of potential terms from the subset, from which he/she selects the SNOMED CT concept that best represents the patient's health issue.

4.4.2 Data entry – use of a local interface terminology mapped to the GP/FP subset

During an encounter in his/her general/family practice, a GP/FP sees a patient who has presented with a newly identified health issue. The GP/FP enters this health issue into his/her EHR by searching for and selecting a term from a local interface terminology into the data field for 'health issue'. A map from the local interface terminology to the SNOMED CT GP/FP Subset allows the term entered to also be represented as a concept from the GP/FP subset for clinical decision support and interoperability. 

4.4.3 Electronic transfer of care (referrals, admissions, handovers, discharge)

A GP/FP wishes to transfer the care of a patient to a medical specialist for further investigation. The GP/FP's EHR contains the SNOMED CT GP/FP subset, and the GP/FP has entered all the patient's health issues into the EHR using the subset. An HL7 referral message is then constructed; containing SNOMED CT coded concepts from the patient's problem list. The message is sent electronically to the specialist who populates his/her EHR using the data contained in the message. This reduces the time needed to take a patient history and enter this data into the specialist's EHR.

4.4.4 Constraint of terminology use for population and subpopulation analysis

A group of GPs are interested in comparing aspects of care across populations of GPs and their patients. The adoption of a subset will, to an extent, constrain the variability of coding of similar issues, conditions and situations that may confound data analysis where very large terminologies such as SNOMED CT are used without constraint.

4.5 Obtaining the GP/FP subset

Initially, the GP/FP subset and map to ICPC-2 was released as a 'technology preview' in February 2014. The RF2 files for the GP/FP Subset and map to ICPC-2 will be updated subsequently to, and in line with each release of the SNOMED CT International Edition.

4.6 Benefits of the subset

SNOMED CT is regarded as the leading global clinical terminology for use in EHRs, however its size makes it unwieldy for use in general/family practice. The GP/FP subset utilises the power of SNOMED CT as a global healthcare terminology, while restricting the concepts available to GPs/FPs to those commonly used in general/family practice. This increases the usefulness of SNOMED CT for GPs/FPs because searches are targeted to the SNOMED CT concepts that GPs/FPs use most often, and, if implemented properly, users should be able to search and select a SNOMED CT concept quickly and easily. 

As stated in Section 4.5, the SNOMED CT GP/FP subset will be maintained and distributed after (and in line with) each release of the SNOMED CT core. As a result, the GP/FP subset is available free of charge to users in IHTSDO member countries.

4.7 Characteristics of the GP/FP subset

The GP/FP Subset contains the following characteristics:

• All non-human concepts are not included

• Only concepts with a status of 'current' (status = 0) have been included, ensuring that the only concepts included are active and able to be used for data entry.

• The Reason for encounter and Health issue subsets have been combined into one subset.

• A series of principles for the development of the GP/FP subset were created during the development phase of the project. These principles are documented in the SNOMED CT GP/FP subset and ICPC mapping project: Phase 2 project report.

• The GP/FP subset will be released using Release Format 2 (RF2) See Section 5.1 of the Technical Implementation Guide for further information about SNOMED CT release formats and RF2.

4.8 Known issues in the GP/FP subset

The GP/FP subset was developed using a 'bottom-up' approach, based on the terms frequently used in general/family practice to describe reasons for encounter and health issues. As a result, it does not contain all the SNOMED CT concepts that could be used to populate the reasons for encounter or health issue data fields in electronic health records. The IFP/GP SIG will add to the content of the subset over time, but it is not intended that the subset will contain all SNOMED CT concepts that could be used to populate these data fields. 

4.9 Implementation of the GP/FP subset

Background about the creation and maintenance of subsets can be found in Section 7.9 of the SNOMED CT Technical Implementation Guide, and Section 7.6.3 discusses the application of Subsets. 

4.9.1 SNOMED CT target content

The GP/FP subset only contains SNOMED CT content from the following hierarchies:

• Clinical finding

• Event

• Procedures

• Situation with explicit context.

4.9.2 Implementation levels

Section 3.3 of the SNOMED CT Technical Implementation Guide describes three implementation levels for some aspects of SNOMED CT deployment. The three levels represent incremental capabilities for implementation broken down into specific dimensions including scope of use, record structure, expression storage, data entry, data retrieval and communication. Guidance provided in this section of the Technical Implementation Guide is also applicable to implementation of the GP/FP subset. 
It must be noted that the GP/FP subset does not inherently contain structures or content to support the implementation of post-coordinated expressions, as required for the highest implementation level within some dimensions. The decision to implement post-coordinated expressions must be made at the local level, with implementers choosing to allow users to created post-coordinated expressions in conjunction with use of the GP/FP subset. 

4.9.3 The user interface

Section 7.6 of the SNOMED CT Technical Implementation Guide provides recommendations and information for vendors about creating a user interface facilitating access to SNOMED CT concepts. 

4.9.4 Use of a secondary search mechanism

The GP/FP Subset contains concepts that are commonly used by GPs/FPs on an international basis, restricting the SNOMED CT concepts available to GPs/FPs to those concepts they are likely to use frequently. However, rare conditions are managed in general/family practice, and GPs/FPs may occasionally need to access a wider source of SNOMED CT concepts to populate their reasons for encounter or health issues.
For this reason, when implementing the GP/FP Subset implementers are strongly encouraged to implement a two-stage search mechanism, where users search for concepts in the GP/FP Subset in the first instance. Then, if a suitable concept cannot be found in the GP/FP Subset, a 'secondary search' is activated, allowing the search to be repeated using a broader set of relevant SNOMED CT concepts.

5 Summary of development activity

5.1 Effective date

The effectiveTime for the content has been set to 20160131 (31st January 2016). 

5.2 Maintenance of the subset and ICPC-2 map

Agreement of changes to both products will be handled through the International Family Practice/General Practice SIG (IFP/GP SIG). 
Requests for future changes will be accepted through mailto:support@ihtsdo.org.