Country / Region
EMEA
Tags
Clinical Practice, Implementation, Mapping, Research, Tooling
At the Department of Public Health and Primary Care of Ghent University, Belgium, a three-pronged project (SNOClass) has started to map core sets of SNOMED CT concepts (relevant for primary care) to the International Classification of Primary Care (ICPC-3), as well as to ICF and ICHI. This project is an initiative of the Belgian Health Terminology Center, started in January 2025 and spanning over 12 months.
ICPC-3 is a classification method for primary care encounters, developed by the WONCA International Classification Committee (WICC). ICPC-3 supports primary care clinicians coding of a patient's reason(s) for encounter, symptoms and complaints, diagnoses, health problems, functioning, environmental factors, personal factors related to health and processes.
A map from SNOMED CT to ICPC-2 existed until January 2019 when it was deprecated after WONCA confirmed the map was no longer maintained and was focusing on successor ICPC-3, an edition providing more comprehensive coverage of functioning and social issues domains that are important in primary care.[J3] Currently, there is no automated method to map SNOMED CT to ICPC-3. This is important to address to optimize the quality of the mapping.
This work is supported by the WHO Collaborating Centre on Family Medicine and Primary Health Care, in collaboration with the Department of Rehabilitation and Units of Family Medicine and Medical Informatics.
Description
The aim is to develop a mapping between SNOMED CT concepts relevant for primary care and the third edition of the International Classification of Primary Care (ICPC-3). To select relevant SNOMED CT subsets, two approaches have been explored.
The first approach was based on the SNOMED CT hierarchy (semantic) tags, but with limited benefits. As the ICPC-3 classification is about General Practice, almost all SNOMED CT domains and hierarchy tags were relevant. With this approach, the total amount of concepts was reduced by 30%, from 370.931 to 258.926 concepts.
To further narrow it down, a second approach was explored, which consisted in reusing existing mappings: 3BT and the General Practitioner Reference Set (GP-Refset).
* 3BT (Bilingual Biclassified Belgian Thesaurus) is an interface terminology of Belgian general practice. More than 51.000 lexical entries have been collected based on daily practice frequency of use and given a unique IBUI (Belgian Unique Identifier) code and corresponding ICD10 and ICPC-2 codes.
* GP-Refset project selected the top 11.000 lexical entries. An exact match to a SNOMED CT concept was possible for 5.308 entries. These have then been matched to 548 out of approximately 1300 ICPC-2 codes. These codes are further specified by adding an ICD-10 code.
Between ICPC generations, a published conversion table of ICPC-2 to ICPC-3 (and 1) provides a bidirectional map.
Building on these previous projects, 5046 lexical entries are already matched to 4160 SNOMED CT concepts, ICPC-2 codes and ICD-10 codes.
The next step will be to identify among the selected SNOMED CT terms the ones that provide at a high level of aggregation an exact one-to-one match with the ICPC-3 classes, and a lower level of aggregation with the ICPC-3 inclusion terms. These exact one-to-one matches between SNOMED CT and ICPC-3, suggested by the previous computerized procedures will be validated by a blinded team of coding experts, with a third reviewer for consensus in case of disagreement.
Results of this project will contribute to the Belgian GP-Refset, to a legacy conversion table to modernize the historical epidemiological datasets, and to a modern sophisticated terminological support tool for high quality end-user data entry at the point-of-care, allowing data entry once, and multiple use afterwards.
Scope
SNOMED CT is the most comprehensive and systematically organized reference terminology globally. It provides codes, terms, synonyms and definitions used in clinical recording of data across all healthcare sectors. Also in Belgium, SNOMED CT is used as the interface in some electronic health records.
How SNOMED CT will be used
This project approaches SNOMED CT as a terminology used in electronic health [J1] records and is working on mapping it to the International Classification Primary Care (ICPC-3) to produce epidemiologically relevant data from GPs registration of patient encounters.
Given the different granularities of the resources, mapping from SNOMED CT (more than 370.000 concepts) to ICPC-3 (more than 1.300 classes) implies considering 3.000 times more concepts than mappings in the opposite direction (from SNOMED CT to ICPC-3). A high number of mappings from several SNOMED CT concepts to one ICPC-3 class (many-to-one) is expected, as well as mappings at a higher level of aggregation and a lower level of granularity.
Why SNOMED CT will be used
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