When Should You Create a SNOMED CT Extension vs. Map to SNOMED CT?
In the ever-evolving world of healthcare, standardizing clinical terminology is critical to achieving seamless data interoperability and supporting high quality patient care. SNOMED CT (Systematized Nomenclature of Medicine – Clinical Terms) plays a pivotal role as the most comprehensive healthcare terminology system, enabling accurate and consistent representation of clinical data.
Organizations using SNOMED CT often face a crucial decision: Should they create a SNOMED CT extension to address their needs, or should they map their existing codes to SNOMED CT? This blog post explores these two approaches and provides guidance to help organizations make informed decisions.
What Are SNOMED CT Extensions and When Are They Needed?
A SNOMED CT extension allows organizations to add concepts, descriptions, or relationships that are not part of the international edition of SNOMED CT. Extensions are essential for addressing specific local or organizational requirements that are not currently covered by the standard.
Use Cases for Extensions:
Regional Requirements: Countries or regions may need to represent unique conditions, procedures, or cultural practices. For example, adding terms for indigenous health conditions or region-specific clinical workflows.
Organizational Needs: Hospitals or healthcare networks may require local codes to capture specialized procedures or internal reporting needs. If a concept or term is missing from SNOMED CT, an extension would allow you to add it on your own time frame.
Specialized Domains: Certain clinical specialties might need terms that are not yet included in the international edition. For example, Veterinary Extension of SNOMED CT.
Cutting-Edge Domains: Research organizations are often working beyond the edges of the traditional healthcare system and need to refer to content that may not yet exist in the standards. For example, new treatments for diseases (like use of gold nanoparticles in cancer) that have not yet been formally approved.
Example: A national health authority might develop an extension to include codes for country-specific public health initiatives.
Benefits of Extensions:
Tailored to local requirements.
Enable detailed clinical documentation and reporting.
Challenges:
Require ongoing maintenance and alignment with SNOMED CT updates.
May lead to fragmentation if not shared widely.
What Does It Mean to Map to SNOMED CT?
Mapping involves linking terms from other coding systems (e.g., ICD-10, LOINC, or proprietary systems) to equivalent SNOMED CT concepts or vice-versa. Mapping is often used to integrate disparate systems and support data migration or analytics. Mappings between two coding systems are not always one-to-one and equivalent to each other which can lead to a loss of meaning.
Use Cases for Mapping:
Legacy Systems: Facilitating interoperability between legacy systems and those using SNOMED CT. In these cases you are trying to exactly represent the legacy coding system with a concept from a standard coding system like SNOMED CT.
Data Migration: Converting existing coded data into SNOMED CT to support longitudinal analysis. Similar to legacy systems, you want to exactly represent the original meaning of the data in the standard coding system.
Unified Reporting: Aggregating data from multiple systems for consistent reporting and analysis.
Example: Mapping laboratory codes from LOINC to SNOMED CT for unified terminology in clinical data exchange.
Benefits of Mapping:
Promotes interoperability across systems.
Simplifies integration with existing datasets.
Enhanced ability to query data using the hierarchies or description logic of a terminology like SNOMED CT.
Challenges:
Mapping quality depends on the accuracy of the linkages.
May not fully represent all nuances of the source terminology.
Mappings must be maintained across versions of the terminologies involved.
When Should You Choose a SNOMED CT Extension vs. Mapping?
Choosing between creating a SNOMED CT extension and mapping to SNOMED CT involves evaluating several factors:
Interoperability:
Extensions cater to local needs but can fragment interoperability if not standardized or shared. In order for any organization you share data with to understand or use your data you will need to share your extension with them. This can be remedied by submitting any locally developed content to a national or even the international edition.
Mapping may ensure compatibility between systems, facilitating cross-system data exchange. However, if not done properly, it can lead to a loss of information due to not mapping to exact meanings.
Maintenance:
Extensions require regular updates to stay aligned with SNOMED CT’s evolving content.
Mappings rely on standard mapping tables but need validation to ensure accuracy as they are also dependent on content changes to both code systems.
Analytics and Data Quality:
Extensions enrich datasets with precise, locally relevant terms. Extensions also have the benefit of utilizing the computability features of SNOMED CT like the polyhierarchical relationships and defining attributes.
Mappings enable consistent data analysis across multiple systems but might result in a loss of specificity.
Data Fidelity:
Extensions allow for the ability to “say what you need to say” regardless of whether that content is available. Extension concepts can be incorporated into the hierarchy to express these finer grained meanings as proper sub-types of standard content.
Mappings only enable linking things already existing in one code system to another. However, mappings from custom/local terminologies can be used in a similar way to say things not yet in the standard but link to the closest available meanings.
What Are the Guidelines for Choosing between a SNOMED CT Extension or Mapping?
To decide whether to create an extension or map to SNOMED CT, follow these best practices:
Evaluate Your Needs:
Is the requirement unique to your organization, or is it part of a broader interoperability goal? Will you need to be able to seamlessly use both SNOMED CT and the other coding system? Will you only need to use the other code system for billing or reporting purposes?
Collaborate with SNOMED Organizations and Affiliates:
Engage with SNOMED International or your national release center to explore existing solutions and avoid duplication.
Leverage Standards:
Use established tools and guidelines for extension development or mapping creation.
Test and Validate:
Validate extensions and mappings to ensure they function correctly in your systems and workflows.
Consider Maintenance Requirements:
As content evolves and changes in either the extension or the map, consider how much work is it to keep that data aligned as SNOMEDCT version updates occur.
Conclusion
Choosing between a SNOMED CT extension and mapping to SNOMED CT is a critical decision that impacts long-term data quality, interoperability, and analytics capabilities. While extensions offer a way to address local and specialized needs, mappings enable broader integration and interoperability.
| Approach | Create a SNOMED CT Extension | Map to SNOMED CT |
|---|---|---|
| Use Case | Adding new or missing concepts that SNOMED CT doesn’t yet contain | Linking local/other terminology codes to existing SNOMED CT concepts |
| Pros | • Tailored to local requirements • Immediate availability of new terms • Full SNOMED CT logic support | • Fosters broader interoperability • Aligns with international standards • Simplifies analytics across systems |
| Cons | • Ongoing maintenance overhead • Potential fragmentation if not shared widely • Requires local release management | • Will lose specificity if no exact SNOMED CT match • Mappings need regular validation across versions |
| Ideal Scenario | Specialized, cutting-edge domains or local/organizational codes that don’t exist in SNOMED CT | Integrating data from legacy systems, billing codes, or other terminologies into SNOMED CT |
Carefully evaluate your organization’s requirements, collaborate with SNOMED International and the appropriate national extension, and adhere to best practices to ensure your chosen approach aligns with your goals. By doing so, you’ll not only optimize your use of SNOMED CT but also contribute to advancing healthcare data standardization globally.