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The aim of the EDQM to SNOMED CT map is to produce as close as possible to an exact semantic match mapping between the EDQM Pharmaceutical Dose Forms in EDQM Standard Terms as the source and the SNOMED CT descendants of 736542009 | Pharmaceutical dose form (dose form) | as targets, to support the use cases described.

The map aims as much as possible for a 1..1 exact semantic match of the pharmaceutical dose forms. In order to achieve that aim, the semantics of each source concept and possible target concepts have been examined in detail, using all available information and ascertaining what within that information was definitional and what was to be considered either descriptional (only) or "implementation guidance" (the latter applying especially for the EDQM Standard Terms).

If, having undertaken that examination, an exact match was not possible, where appropriate within existing guidance, additional concepts were authored within SNOMED CT to support an exact match. For some individual concepts and some groups of concepts (for example, those with more than one intended site), this is an ongoing process and may involve further changes within the SNOMED CT dose form content. 

Although the process for change within EDQM Standard Terms is more complex for a variety of various reasons, some recommendations for change to EDQM Standard Terms have also been made, especially when these are in accordance with recommendations from other groups working with the EDQM Dose Forms.

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"No map" codes

When an EDQM Standard Terms code is in the scope of the map but no semantically matching concept is present in SNOMED CT this is considered a "No map". A significant number of new PDF concepts have been authored in SNOMED CT to resolve this "No map" situation when it has been possible to confirm that the PDF is used to describe one or more medicinal concepts authorised in member countries. As noted in the section describing the EDQM PDFs, EDQM will categorise a dose form as for "human and veterinary use" even if it is requested for initial use with a veterinary medicinal product unless the PDF is specifically for veterinary application (e.g. "Continuous-release intraruminal device"). Therefore there are EDQM PDFs that are within the scope stated above but which have never been used to describe a medicinal product for human use.  Whilst it would be possible to author PDF concepts in SNOMED CT that are an exact match for many of these EDQM PDFs, having concepts in SNOMED CT that are not directly required to support patient care is not sensible. However, as each of these EDQM PDFs have been evaluated, they have been assigned an additional category:

• PDF concepts that SHOULD be added to SNOMED CT if requested by a member to support authoring of medicinal products.  These are PDFs whose semantics can be fully defined using the SNOMED CT PDF concept model and would be clinically useful PDFs for the use cases.
  • For all of these, a fully specified name and logical definition have been suggested.
• PDF concepts that COULD be added to SNOMED CT if requested by a member to support authoring of medicinal products.  . The Dose Form should have an international value for the SNOMED community. These are PDFs whose semantics are not as easy to fully define in SNOMED CT and/or for which there are some reservations as to their clinical usefulness.
  • For these, a fully specified name and logical definition have been tentatively suggested.
• PDF concepts that SHOULD NOT be added to SNOMED CT.  These are concepts with ambiguous semantics or significant reservations about their clinical usefulness.  There are very few of these, and they mostly occur from early, less rigorous requests to EDQM or to describe products that would now not be considered medicinal products. (for example, the EDQM term "implantation tablet"; any new products would be encouraged to use the term "implant").

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Association/Correlation and Cardinality

The aim is for the source and target to be "equivalent" (i.e. an exact semantic match).

However, some maps will not be exact. In these situations, the map will have a different association type:

A narrower (than) map: This association is used when the meaning of the SNOMED CT concept is is narrower than the  the meaning of the EDQM concept.

• Another way of saying this is that this is a "broad-to-narrow" map (from the EDQM source concept to the SNOMED CT target concept); this is a 'narrower' mapping because the map is to a concept with a narrower meaning than the source concept
  
  • For example, a mapping between "Medicated sponge"  in EDQM to "Conventional release cutaneous sponge (dose form)" in SNOMED CT is "narrower" -  as the EDQM concept is very generic in terms of not specifying an intended site of administration, whereas the SNOMED CT concept does explicitly have an intended site of administration (cutaneous).
• Note that when 'Narrower than target' maps are made, these may give a 1..* cardinality between an EDQM concept and SNOMED CT concepts, especially when the mapping is considered in its entirety.

A broader (than) map: This association is used when the meaning of the SNOMED CT concept is is broader than the  the meaning of the EDQM concept, and it is not possible or considered reasonable to author new, more granular SNOMED CT concepts

• Another way of saying this is that this is a "narrow-to-broad" map (from the EDQM source concept to the SNOMED CT target concept); this is a 'broader' mapping because the map is is to a concept with a broader meaning than the source concept
  
  • For example, a mapping between  "Inhalation powder, hard capsule" in EDQM to "Conventional release powder for inhalation (dose form)" in SNOMED_CT is "broader" - as the EDQM concept is precise, particularly in regard to the encapsulation of the dose form whereas the SNOMED CT concept is less explicit, with no description of encapsulation of the inhalation powder.
• Note that when "'Broader than target’ maps may be made; these may give a *..1 cardinality when the mapping is considered in its entirety.

In all cases where the mapping is 'Broader than’ or 'Narrower than', implementation guidance is provided.