Introduction

The SNOMED CT terminology provides a common language that enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care. The International Health Terminology Standards Development Organisation (IHTSDO^®) maintains the SNOMED CT technical design, the content architecture, the SNOMED CT content (including the concepts table, the descriptions table, the relationships table, a history table and mappings), and related technical documentation. 

This document is intended to give a brief description, background context and explanatory notes background to the Mapping Conventions used on the SNOMED CT International/ICH (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) work through the EU funded WEB RADR 2 project and the resulting Release package and the resulting SNOMED CT/MedDRA maps, which are being published as an Alpha release at this time with intention to publish a production release in April 2021. This document covers the background to the collaboration between SNOMED International and ICH, through the MedDRA MSSO, as part of the project and goes on to cover the consequent release artefacts.   It is not a detailed technical document of SNOMED CT, MedDRA or the SNOMED CT International/ MedDRA release. Nor does it seek to provide an editorial policy for this content though does provide details of the Mapping conventions applied.

This ALPHA release package is distributed for evaluation purposes only.  It must not be used in production clinical systems or in clinical settings, or distributed to Affiliate Licensees or any third parties.   

Audience for this document

This document should be read by all those (SNOMED International National Release Centers, vendors of electronic health records, terminology developers, Regulators and Pharmaceutical Industry) with an interest in the usage of this content in SNOMED CT and its linkage with MedDRA i.e. the SNOMED CT to MedDRA and MedDRA to SNOMED CT maps based on a priority set of MedDRA. 

Background

In 2018, SNOMED International and ICH joined the WEB-RADR 2 project, funded by Innovative Medicines Initiative (IMI). SNOMED International and ICH lead the effort to develop 2 maps between SNOMED CT and MedDRA. A specific work package was devoted to this purpose and included participants from regulatory authorities and industry as well as SNOMED International and MedDRA MSSO. The project delivered the following:

• 2 maps (MedDRA to SNOMED CT and SNOMED CT to MedDRA) of frequently used pharmacovigilance MedDRA terms that were identified from databases from the UK’s Medicines & Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA). This subset represents the high value terms to support interoperability between the terminologies.
• A set of Mapping conventions which were drafted as part of a pilot set and updated for the main body of work.
• A small number of content additions to SNOMED CT in support of the MedDRA high value terms as defined by scope and editorial rules of SNOMED CT.

The Use cases of the project were defined as:

SNOMED CT to MedDRA map:

Key pharmacovigilance concepts when coded in SNOMED CT in an electronic health record could be converted to MedDRA for the purpose of adverse event reporting to regulatory authorities or for the purposes of epidemiological research. 

The mapping work was undertaken using dual independent review by mappers who were Consortium members of the WEB RADR 2 project and experts in either SNOMED CT or MedDRA. Quality Assurance, based on the mapping conventions, was managed as part of the process by SNOMED International and MedDRA MSSO (on behalf of ICH) and technical assurance reports provided weekly using the Mapping tool used by all participants. A big thank you is offered to all contributors to the Maps. The Mapping Conventions used are provided for information as part of this package.

In parallel to the mapping work, the operational aspects have been worked on to agree activities and processes to enable the 2 Maps to move in to Production in April 2021 and from there to be maintained and updated according to changes within the 2 terminologies and Use Case based requirements for additions to the Maps - thus meeting one of the key requirements of IMI to produce products in the project that are sustainable over time.

At this time, SNOMED International and ICH are seeking feedback on the Alpha version of the 2 Maps, and a Test/Review protocol has been produced as part of this package which indicates some of the areas on which feedback is invited. The Test/Review period ends on 30 September 2020, after which work will be undertaken to update the Maps in line with January 2021 SNOMED CT International Release and MedDRA September 2020 release. A report of the feedback will be made available. Please note that the Maps will NOT be extended beyond current scope for the Production release. The Production release in April 2021 will be available to licensed users of either SNOMED CT of MedDRA.

MedDRA to SNOMED CT map:

Clinical care decision support: Terms coded in MedDRA representing adverse events, warnings, and other regulatory information in product labeling could be converted into SNOMED CT so that the information is integrated into the electronic health record or decision support system to be visible to healthcare professionals when prescribing, dispensing, or administering the product to patients.

Use Cases of the

The scope of the SNOMED International and ICH work through the WEB RADR 2 project has been outlined above, and the 2 organizations are now in the process of formalizing the next steps in a Collaboration agreement which ensures that the 2 Maps are updated, after feedback from the Alpha release, to form the Production release in April 2021. 

Under the terms of the Collaboration agreement between SNOMED International and the ICH, the Maps will be issued annually by both SNOMED International in RF2 format and  MedDRA MSSO in spreadsheet format. Documented quality assurance processes will ensure both formats are the same and supporting materials are produced jointly. In addition, criteria for extending the Maps will be agreed and managed through agreed processes to ensure that the products meet the needs of the different stakeholder groups as defined by the Use Cases.

Release content

Overview

The MedDRA derivative content is released under a project-specific module (816211006) with component identifiers that are within the main IHTSDO (International Release) namespace. Placement in the SNOMED hierarchy is based on existing MedDRA groupings ('collective terms'). 

Content detail

The content is based on a high value set of MedDRA terms identified as part of the WEB RADR 2 project, taking data from European Medicines Agency and  UK’s Medicines & Healthcare products Regulatory Agency (MHRA) - just under 7500 were evaluated for being in scope of SNOMED CT. Approximately 100 new concepts have been added to SNOMED CT as a consequence of this work.

Dependent Content

The January 2019 SNOMED CT International Edition is the baseline for the April 2020 SNOMED CT MedDRA Map package, and therefore all filenames and record have been assigned the value of 20190131 in the effectiveTime field. The Maps use MedDRA version 21.1, released September 2018.

Obtaining the Alpha release

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

The  spreadsheet versions of the Maps are available for download from the  MedDRA website: 
xxxxxxxxxxxx

Reviewers of the Maps should have a licence for either MedDRA and SNOMED CT.

Feedback

Feedback should be sent jointly to info@snomed.org and INSERT MedDRA  DETAILS. The Test/Review protocol document as part of this package provide guidance on the type of feedback the 2 parties would like to receive. In addition, the Mapping Conventions document is part of this package so part of feedback.

Technical Notes

RF2 package format

The RF2 package convention dictates that it contains all relevant files, regardless of whether or not there is content to be included in each particular release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and also files that are intentionally left blank (including only a header record).  The reason that these files are not removed from the package is to draw a clear distinction between:

1. ...files that have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in this or future releases, and 
2. ...files that just happen to contain no data in this particular release (and are therefore included in the package but left blank, with only a header record), but are still relevant to RF2, and could therefore potentially contain data in future releases.

This allows users to easily distinguish between files that have purposefully been removed or not, as otherwise if files in option 2 above were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

RF2 map files

Both SNOMED CT to MedDRA and MedDRA to SNOMED CT simple map files are contained in the same package, and therefore are linked by the same moduleID (816211006).

However, they can be individually identified by their relative refsetID's, as follows:

Maps 

A major goal of the WEB-RADR 2 project is to use the enhanced functionality of the mobile application to facilitate exchange of data between regulatory databases (which use MedDRA) and healthcare databases/electronic health records (which use SNOMED CT). Two maps are therefore being developed (from MedDRA to SNOMED CT and SNOMED CT to MedDRA) to support seamless data exchange within the application platform. The starting sub-set of ~7,400 terms to be mapped in the project define a set of key pharmacovigilance terms that need to be linked to their counterparts in either terminology.

In one use case, these key pharmacovigilance concepts when coded in SNOMED CT in an electronic health record could be converted to MedDRA for the purpose of adverse event reporting to regulatory authorities or for the purposes of epidemiological research. In the opposite direction, these same key terms coded in MedDRA representing adverse events, warnings, and other regulatory information could be converted into SNOMED CT so that the information is available in the patient’s record to aid in clinical decision-making. 

Timeline for Creation of the Maps 

Test mapping (760 terms, February-March 2019) › MedDRAv21.1

› SNOMEDCTversionJan2019Internationaledition
» Completion of mapping (1 May 2019 onwards, confirmed after test)

› MedDRAv21.1
› SNOMEDCTversionJan2019Internationaledition

» Impact assessment of July 2019 release of SNOMED CT and MedDRA v22.0 and v22.1 (after completion of the map)

Post-mapping note: in finalizing the mapping, an impact assessment was performed to determine which MedDRA terms had been made non-current and which SNOMED CT concepts had been made inactive. These terms were then removed from the mapping. No other changes were made to the mapping based on terminology version updates, i.e., any terms that had been proposed and added to SNOMED CT or any medically better matches to a mapped term were not included in the final maps. 

The final maps are based on: › MedDRAv21.1

› SNOMEDCTversionJan2019Internationaledition
Any terms that are non-current (MedDRA) or inactive (SNOMED CT) as of October 2019 are excluded.

Note that it proved not possible to map all of the starting sub-set of ~7,400 terms given the different scopes of the two terminologies and the way they are structured, i.e., some terms were unmappable. Other terms were identified as potentially mappable and will be considered for possible addition to SNOMED CT in a future release. In finalizing the maps, other actions were taken that impacted the number of terms; these include adding missing US and UK spelling variants to the MedDRA to SNOMED CT map and removing unqualified test name terms from both maps. These actions are documented in Post-Mapping Notes below. Overall, the final maps produced in this project have decreased numbers of terms compared to the starting sub-set. 

General Mapping Guidance 

MedDRA hierarchies 

MedDRA groups its terms in a five level hierarchy. The Preferred Term (PT) level represents single medical concepts and the Lowest Level Term (LLT) level represents synonyms, lexical variants, and sub-elements. 

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Determining possible equivalencies 

Check SNOMED CT concepts and MedDRA terms against hierarchy placement to determine if concepts/terms are equivalent.

Example

• ›  VitaminD.Directlexicalmatchbutis a test name in MedDRA and a substance in SNOMED CT

• ›  Inthiscase,LLTVitaminDshould be mapped instead to SNOMED CT Vitamin D measurement (procedure) 

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Mapping to an exact conceptual match 

Mapping in both directions is to an exact conceptual match for the concept/term. Such mappings will all be flagged with the mapping parameter (attribute/relation) “Exact Match”. This is defined as the source terminology concept/term and the target terminology concept/term having the same conceptual medical meaning.

Examples

• ›  LLTPermanentcardiacpacemakerinsertionmapstoSNOMEDCTImplantationofcardiac pacemaker (procedure)

• ›  SNOMEDCTImplantationofcardiacpacemakermapstoLLTCardiacpacemakerinsertion

• ›  LLTEmotionallabilitymapstoSNOMEDCTMoodswings

›  SNOMEDCTMoodswingsmapstoLLTMoodswings

Note that while Emotional lability is a synonym of Mood swings in SNOMED CT, in MedDRA, LLT Emotional lability is under PT Affect lability (HLT Affect alterations NEC) and LLT Mood swings is under PT Mood swings (HLT Fluctuating mood symptoms). Both terms are under HLGT Mood disorders and disturbances NEC. The two terminologies use different editorial guidance for their organisation and in some cases such as this one where the structure of SOC Psychiatric disorders is based on DSM-5, closely related terms may be in different parts of the hierarchy. For the purposes of the mapping, a pragmatic approach will be taken and concepts/terms will either be exact conceptual matches or unmappable.

Unmappable Concepts / Terms

Any concepts/terms that are not an Exact Match will be flagged as “Unmappable in SNOMED CT” or “Unmappable in MedDRA” as appropriate. This will identify relevant concepts in either terminology that might be missing and are required to provide a more complete mapping. The addition of any new content will then be discussed by the relevant terminology organisation.

Examples

• ›  LLTNon-ischemiccardiomyopathyandSNOMEDCTNonischemiccongestivecardiomyopathy are not an exact match because the SNOMED CT concept has the additional concept of “congestive”. This would be flagged as “Unmappable in MedDRA” and a more specific term, Non- ischemic congestive cardiomyopathy, would be considered for addition to MedDRA.

• ›  LLTProstatecancerstageIVandSNOMEDCTCarcinomaofprostatearenotanexactmatch since the stage is not included in the SNOMED CT concept. This would be flagged as “Unmappable in SNOMED CT” and a more specific term, Prostate cancer stage IV, would be considered for addition to SNOMED CT. (See also Principle 8 for conventions for tumour types and stages). 

MedDRA LLT to SNOMED CT FSN

The MedDRA to SNOMED CT map will be undertaken first (LLT to FSN). That same SNOMED CT concept (FSN) will then be mapped in the reverse direction to the equivalent MedDRA LLT, aiming for the same semantic match.

Mapping multiple LLTs to a single FSN

In many instances, the LLT mapped from MedDRA to SNOMED CT will be the same as the LLT when mapped in the reverse direction from SNOMED CT to MedDRA, i.e., LLT 1 to FSN; FSN to LLT 1. In others, the LLT mapped from MedDRA to SNOMED CT will differ from the resulting LLT when mapped in the reverse direction, i.e., LLT 1 to FSN; FSN to LLT 2. This occurs because the two terminologies differ with respect to lexical variants, spellings, etc. However, the clinical meaning of the term/concept should always be the same in both directions. See Principles 1 and 2 for specific examples.

While more than one LLT can map to a single FSN, in the reverse direction going from SNOMED CT to MedDRA, this will always be a 1:1 map. This supports the use case of using SNOMED CT EHR data to report Adverse Events without double counting.

Map active content only

Map active SNOMED CT concepts and current MedDRA LLTs only

Mapping domains

Typically the map will use (finding/disorders), (event), (procedure), and (situation with explicit context) concepts in SNOMED CT. However, there may be valid exceptions.

Example

› LLTBloodpressuresystolicmapstoFSNSystolicarterialpressure(observableentity).

The map will not use (substance) concepts in SNOMED CT since the names of drugs and other substances are out of scope of MedDRA. 

Specific Mapping Conventions

Principle 1. Map MedDRA LLT to SNOMED CT concept, finding the same semantic match.

Use Fully Specified Name (FSN) to confirm meaning. The same applies to the SNOMED CT concept to MedDRA LLT map.

Example

› MedDRALLTRhabdomyolysismapstoSNOMEDCTRhabdomyolysis(disorder)
- DonotmaptoSNOMEDCTRhabdomyolysis(morphologicabnormality)asthisconcept

refers to a pathological related finding rather than a clinical one 

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SNOMEDCTRhabdomyolysis(disorder)mapstoLLTRhabdomyolysis 

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Note that in this example, the starting LLT (Rhabdomyolysis) in the MedDRA to SNOMED CT map is the same as the LLT (Rhabdomyolysis) in the reverse SNOMED CT to MedDRA map. i.e., LLT 1 to FSN and FSN to LLT 1. 

Principle 2. When identifying maps, only use the synonyms in SNOMED CT to inform choice of the FSN. 

The tool will not permit mapping to synonyms.

Example

› MedDRALLTSomnolencemapstoSNOMEDCTDrowsy(finding)
› SNOMEDCTSomnolenceisasynonymofDrowsy(finding)andcannotbeusedtomap.
› OtherLLTsunderPTSomnolencesuchasLLTSleepiness,LLTSleepy,andLLTDaytime

sleepiness are also included in the list of terms to map and these will also map to SNOMED CT Drowsy (finding), i.e., a many to one map. 

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In the reverse direction, SNOMEDCT Drowsy maps to MedDRA LLT Drowsiness(1:1map) “Drowsy” is not in MedDRA, only LLT Drowsy on awakening. MedDRA LLT Drowsiness is closest match to SNOMED CT Drowsy. 

Note that in this example, the starting LLT (Somnolence) in the MedDRA to SNOMED CT map differs from the LLT (Drowsiness) in the reverse SNOMED CT to MedDRA map. i.e., LLT 1 to FSN (Drowsy) and FSN to LLT 2. This results from finding the closest match to SNOMED CT Drowsy which is LLT Drowsiness in MedDRA. All of the maps represent the same medical meaning however: LLT Somnolence and LLT Drowsiness both are under PT Somnolence and they are represented in SNOMED CT as FSN Drowsy (with its synonyms including Somnolence, Drowsiness, Sleepiness, etc.) 

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Principle 3. Not Otherwise Specified (NOS) and Unspecified terms in MedDRA

• »  In the MedDRA to SNOMED CT map, map NOS and unspecified LLTs to the unqualified SNOMED CT concept, i.e., without any further classification

  Example

  • ›  LLTPainNOSmapstoSNOMEDCTPain(finding)

  • ›  LLTNon-autoimmunehemolyticanemia,unspecifiedmapstoSNOMEDCTNon-autoimmune

    hemolytic anemia (disorder)

• »  NOS and unspecified concepts will not be added to SNOMED CT

• »  In the SNOMED CT to MedDRA map, the SNOMED CT FSN is mapped to the unqualified LLT, i.e., do

  not map to NOS or unspecified LLTs in this direction

  Example

  • ›  SNOMEDCTPain(finding)mapstoLLTPain

›  SNOMEDCTNon-autoimmunehemolyticanemiamapstoLLTNon-autoimmunehemolytic anemia

Principle 4. UK English and US English variants

For MedDRA to SNOMED CT map:

• »  Map both US and UK spelling variants in MedDRA to the SNOMED CT concept, i.e. the FSN (US and

  UK spellings (descriptions) are synonyms and can’t be used to map)

  Example

  › LLTEdemaandLLTOedemamaptoSNOMEDCTEdema(cardinalityof1:1)

• »  If the MedDRA source data set contains only either the UK or US spelling of an LLT, the MSSO will

  identify and review the equivalent alternate missing spellings for possible addition to the mapping.

  Post-mapping note: in finalizing the mapping, all “missing” spelling variants in the MedDRA source data were identified and mapped to the appropriate FSN (US spelling). 

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For SNOMED CT to MedDRA map:

Example

› FSNEdemawillmaptoLLTEdema(1:1cardinality) 

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Note that clinical records using SNOMED CT use either UK or US spellings. When SNOMED CT is implemented in EHRs, a language subset (UK or US English) will be implemented by the system depending on the country of location. The end user will thus view the US or UK synonyms but these are represented by the unambiguous SNOMED CT concept which uses the US spelling.

Every PT in MedDRA has an LLT that is identical to it and shares the same code. In MedDRA, UK English spelling is used at the PT level and above; US spellings are only represented at the LLT level. Analysis is performed at the PT level. 

In the use case of taking SNOMED CT EHR data and converting it to MedDRA to report or count adverse events (AEs), one needs to avoid double counting. The 1:1 cardinality from SNOMED CT (US spelling) to MedDRA (US spelling) would ensure that events are only counted once in MedDRA. Maps are generated based on SNOMED CT concepts; whether the EHR uses the SNOMED CT US spelling or the UK spelling, both would map via the FSN to the same single term in MedDRA.

Principle 5. Combination terms and infection/body site

» Map MedDRA LLT to an equivalent SNOMED CT combination term if available Examples

› LLTDementiaduetoParkinson’sdiseasemapstoSNOMEDCTDementiaduetoParkinson’s disease

› LLTEscherichiaurinarytractinfectionmapstoSNOMEDCTEscherichiacoliurinarytractinfection

» Similar principles apply in the reverse SNOMED CT to MedDRA direction
» If an equivalent combination term is not available in either terminology, flag as Unmappable for

discussion and potential addition 

Principle 6. Test names and test results

» MedDRA test name term concepts will generally be found in (procedure) concepts in SNOMED CT Examples

› MedDRALLTCholesterolmapstoSNOMEDCTCholesterolmeasurement(procedure),not SNOMED CT Cholesterol (substance)

» MedDRA test results are typically found in SNOMED CT (finding) Examples

• ›  MedDRALLTBloodglucoseincreasedmapstoSNOMEDCTIncreasedglucoselevel(finding)

• ›  SNOMEDCTIncreasedglucoselevelmapstoMedDRALLTGlucoseincreased(SOC

  Investigations) 

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MedDRA has important exceptions for the following high/low, increased/decreased terms which are considered to be disorders rather than investigations based on the common use of these terms:

› LLTBloodpressurehigh(PTHypertension)
› LLTBloodpressurelow(PTHypotension)
› LLTHightemperature(PTPyrexia)
› LLT/PTSputumincreased(HLTCoughingandassociatedsymptoms) › LLT/PTSputumdecreased(HLTCoughingandassociatedsymptoms)

The corresponding SNOMED CT concepts will also therefore be disorders.

Examples

› LLTBloodpressurehighmapstoSNOMEDCTHypertensivedisorder,systemicarterial(disorder) › LLTBloodpressurelowmapstoSNOMEDCTLowbloodpressure(disorder)

Post-mapping note: although unqualified test name terms were included in the MedDRA source data, it proved challenging to map many of them to SNOMED CT. In addition, since these terms only convey that a test was performed, they were considered not to be of value from a pharmacovigilance or clinical information perspective. Therefore, unqualified test name terms were removed from the final mapping. 

Principle 7. Specimen type

• »  If the specimen type is not specified in the source concept/term, it should be mapped to the concept/term without the specimen type, if available

• »  If the specimen type is not specified in the source concept/term and the concept/term without the specimen type is not available in the target terminology, it is acceptable to default to blood or the most common specimen type for that particular test

• »  The default specimen type will be serum, not plasma, if blood is specified. Try to preserve the specimen type whenever possible.

  Examples

  • ›  LLTLactatedehydrogenasemapstoSNOMEDCTLactatedehydrogenaselevel(nottoSNOMED CT Plasma lactate dehydrogenase level)

  • ›  LLTDruglevelincreasedmapstoSNOMEDCTBlooddruglevelhigh(thereisnodruglevelhigh concept without the specimen type available so it is acceptable to default to blood)

  • ›  LLTLactatedehydrogenaseincreasedmapstoSNOMEDCTSerumlactatedehydrogenaselevel elevated (concepts for the increased/elevated term without the specimen type, or specifying blood or plasma are not available so it is acceptable to map to serum in this case)

  • ›  LLTBloodcreatininemapstoSNOMEDCTCreatininemeasurement,serum Principle 8. Tumour types and stages

• »  If SNOMED CT does not contain an FSN with both the histopathologic type and site of the tumour, the MedDRA term should be flagged as “Unmappable in SNOMED CT” and reviewed for possible addition.

  Example

  › LLTRenalgranularcellcarcinomadoesnothaveacorrespondingFSNwithinSNOMEDCTand should be marked Unmappable.

• »  SNOMED CT does not contain all stages for specific tumour types. If the tumour stage concept is not available in SNOMED CT for a particular stage term in MedDRA, the term should be flagged as “Unmappable in SNOMED CT” and reviewed for possible addition.

  Example

  › LLTBreastcancerstageIIIdoesnothaveacorrespondingFSNwithinSNOMEDCTandshould be marked Unmappable.

• »  When a “recurrent” cancer term is not available in SNOMED CT then the term should be mapped to the primary cancer.

  Example

  › LLTNon-smallcelllungcancerrecurrentmapstoFSNNon-smallcelllungcancer 

When a MedDRA term specifies cell type and site, in addition to staging, try to preserve all three aspects of the concept in the SNOMED CT map.

Examples

• ›  LLTLungadenocarcinomametastaticmapstoFSNAdenocarcinomaoflung,stageIV

• ›  LLTAdenocarcinomaofcolonstageIVisunmappableduetothelackofaterminSNOMEDCT

  that captures Adenocarcinoma + Colon + stage IV/4/metastatic, including the “metastatic from” form referenced below.

  The exceptions to this principle are the stage 4 or metastatic cancers.

• »  For metastatic or stage 4 cancers, when an exact match is not available, “[Primary site] metastatic

  cancer” LLTs map to the similar “Metastasis from [primary site]” FSN

  Example

  › LLTLungcancermetastaticmapstoFSNMetastasisfrommalignantneoplasmoflung

• »  Metastatic primary site terms are synonymous with stage IV/stage 4 if the metastatic term is not available

  Example

  › LLTLungadenocarcinomametastaticmapstoFSNAdenocarcinomaoflung,stageIV

• »  Close attention should be given to the “secondary from” and “metastatic to” terminology.“ Metastases

  [organ]” LLTs map to FSNs of “Secondary malignant neoplasm of [organ]”

  Example

  › LLTMetastasestospinemapstoFSNSecondarymalignantneoplasmofvertebralcolumn Principle 9. Natural word order

» When mapping from SNOMED CT to MedDRA and there are several lexical variant LLTs, the one that uses natural word order should generally be chosen. However, because of the granularity of MedDRA, there may be several LLTs under a PT that are all equally acceptable. If the map specialists happen to choose different ones, the map lead will mark them as not in conflict and select one LLT as the mapped term.

Examples

• ›  SNOMEDCTHyperpigmentationofskinmapstoLLTSkinhyperpigmentation(naturalwordorder) rather than LLT Hyperpigmentation skin

• ›  SNOMEDCTCollapseofvertebracouldmaptoLLTCollapsedvertebraorLLTVertebralcollapse. Both use natural word order and are under PT Spinal compression fracture. 

Principle 10. Punctuation marks

SNOMED CT concepts typically do not include punctuation marks such as hyphens or slashes and will be mapped to the equivalent MedDRA term that also does not include these marks. If there is no MedDRA term without punctuation marks available, the SNOMED CT term will be mapped to the equivalent MedDRA term with punctuation marks. New terms without punctuation marks will be considered for potential addition to MedDRA.

Example

› ForSNOMEDCTAttentiondeficithyperactivitydisorderthereareonlypunctuatedLLTs:LLT Attention deficit/hyperactivity disorder and LLT Attention deficit-hyperactivity disorder

Principle 11. Increased/high and decreased/low qualifiers

In both MedDRA and SNOMED CT, qualifiers for investigation results such as increased/high/elevated and decreased/low are generally used synonymously and can be used to map in both directions.

In both terminologies, the clinical meaning of the “increased” qualifiers can refer to an increase from a previous baseline or an increase above the normal range for that parameter. Similar considerations apply to concepts/terms that are “decreased”. Since it is not known from the report which clinical meaning applies unless one reviews the actual laboratory data, the qualified investigation terms in each terminology will be mapped to their equivalent counterparts. In practice, it is likely that “increased” and “decreased” are generally used by reporters to refer to changes above and below the normal reference ranges (see Increased bilirubin level example below for how this is sometimes reflected in the SNOMED CT hierarchy). However, for the purpose of this bi-directional mapping, the concepts/terms will be mapped strictly to their equivalents since the underlying clinical meaning is not known on an individual case basis.

Example

› LLTBilirubinelevatedmapstoSNOMEDCTIncreasedbilirubinlevel 

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(finding). Note that the interpretation is “Above reference range”. 

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Example

› LLTBloodpressuresystolicincreasedmapstoSNOMEDCT Increased systolic arterial pressure (finding). Note that in this case the interpretation is “Increased” but it does not state if this is above the reference range. 

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