OHDSI Home | Forums | Wiki | Github

SNOMED Units issue

Vocabulary Users
#1

Seems like instead of having 160 SNOMED CT units being standard we now only have 74 of them as standard concepts (between v5.0 17-JUL-15 to v5.0 11-MAR-16) Any particular reason of the random ‘un-standardizing’ of them?

IMO, this will surely break many ETL’s as some of the major units as: ml, mg, mg/kg are not standard anymore, but others like ‘pizza based’ (I am not kidding - concept_id = 45756972) are still standard.

I am also losing things that map to units like: patch, capsule, etc. which all have high frequency in the dataset I am mapping now, and the vocabulary offers no equivalents on UCUM or the other Unit domain vocabularies.

Is it safe for me to try to map the now non-standard ones to UCUM standard concepts? or this will get axed randomly in the future as well? I believe something that lets people know what will get zapped and when would be greatly beneficial.

#2

Juan:

The SNOMED units were never supposed to be standard. We use UCUM out of Regenstrief. They won’t be axed. In fact, they have a generic way to create new ones very easily. And yes, most of the SNOMED ones are mapped to the equivalent UCUM ones. But you may want to go to UCUM right away.

These are actually not units. The unit is “1”. In UCUM, you can have them anyway in curly brackets ("{pizza}"), but you may as well leave the unit out entirely.

Let me know.

#3

Thanks for clearing this out, I will only try to use UCUM from now on. I don’t know how something can accidentally be left to be standard when it was not the intention :wink:

All the mapping conventions should be made 100% clear on the documentation, as using the limiting by domain_id and standard_concept rule certainly fails in this case and will lead to future headaches, in other sites, when the rest of the SNOMED units get unstandardized.

#4

@Juan_Banda:

Agreed.

About concepts getting unstandardized: The concept_id and concept_code/vocabulary_id combination of a concept with a certain semantic meaning never changes, but everything else can: concept_name, standard_concept, concept_class_id, domain_id and the validity information can. So, nobody should rely on a concept to stay Standard forever.

t