I’m looking for some guidance about how to handle rows in the Observation table when there are multiple maps_to_value concept relationships.
I have a single source concept that maps to a single standard concept, but the source concept has 2 different concepts with maps_to_value relationships.
When I join the data to the Concept Relationships table on the “maps_to_value” relationship I’m getting row expansion due to the multiple mappings. Both mapped values are valid, standard concepts.
i.e.
Should we create 2 rows in the Observation table or do we need to find a way to choose 1 value concept?
Neither the CDM Rules nor the Themis conventions give guidance in this situation. Are there any other examples where a single source concept_id maps has 2 different concepts with maps_to_value relationships?
I’m also going to tag a couple vocab team members because I don’t think this is the best mapping.
This concept represents a documentation event based on a past history of some labs. I believe this should map to a concept_id about documentation being completed, probably in the Observation domain. And not to a past history of labs event. I think it’s fairly worthless concept, I can’t even imagine a use case for this idea.
@MPhilofsky Besides the mapping is correct or wrong:
If you have one “Maps to” and many “Maps to value” this is not the explosion yet. You’ll get two CDM records as expected, but there’s no ambiguity which “Maps to value” belongs to which “Maps to”. So even though it’s not properly documented, technically you’re good.
But it gets worse when you have 2 or more of each relationship type. In this case you get an explosion because you don’t know which “Maps to value” belongs to which “Maps to”.
To address this problem just recently we implemented metadata, and particularly the relationship_group. It tells you how to organize relationships into the groups so that you don’t get unexpected permutations.
But please don’t expect the problem is completely solved - we introduced it only for a portion of concepts. Maybe we should think how to prioritize the worst cases going forward.
Are there any examples of this with the vocabulary?
@KSimon I realized I didn’t answer your question completely. Create two records in the OMOP CDM. They both will have the same standard concept_id, but will have different value_concept_ids.
I’ve made a note to update the documentation to give guidance with this situation.
