openEHR, Snomed and Measurement units

Question

I'm new to openEHR and snomed. I'm wanting to store information pack definition for a tobacco summary. How do I go about storing the measurement units (grams, oz, number of cigarettes)? Is there a reference list of these in either of the standards?

Thanks

Answer 1

OpenEhr has an own Unit list from which you should choose a unit in a DvQuantity, but since short time, in the specs, the newest version, is described that you must use a unit from the UCUM standard. Check the description for DataTypes in the specifications.

You can find the UCUM standard here. The link is published by the Regenstreif institute (the same institute which serves the LOINC standard), so it is stable. http://unitsofmeasure.org/ucum.html

There is a Golang-UCUM-library: https://github.com/BertVerhees/ucum

Answer 2

Your question should not be about storing, it should be about modeling with openEHR. Storage of openEHR data is a separated issue.

For modeling, you will need first to understand the information model, the structure, the datatypes, etc. You will find some types that might be useful in your case, for instance using a DV_COUNT for storing the number of (this is for counting, like number of cigarettes), that doesn't have units of measure since is a count. If you want to store volume or weight, the openEHR information model has DV_QUANTITY. For standard units, as Bert says, you can use UCUM. For non standard units, you might need to choose a different datatype since the recommendation for DV_QUANTITY.units is to use UCUM (Unified Code for Units of Measure).

When you have that figured our, you need to follow the openEHR methodology for modeling, using archetypes and templates. A template would be the final form of your structure that can be used in software. At that moment you can worry about storage.

Storing today is a solved problem. There are many solutions, using relational, document and mixed databases. My implementation, the EHRServer, uses pure relational approach. But you can create your own, just map the openEHR information model structures to your database of preference, starting from the datatypes.

And of course, start with the openEHR specs: https://www.openehr.org/programs/specification/workingbaseline

BTW, SNOMED doesn't play any role here, not sure why you mentioned that in the title. You need to understand the standards before trying to implement them.