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What is the difference between SDTM and OMOP CDM

CDM Builders
#1

Hi All,

This is my first question which I am posting as I am new to OMOP and Common Data Model, I wanted to know what is the difference between SDTM and OMOP CDM. There is also one more question which I had, I was going through the document provided by OMOP regarding how to implement the CDM and the details about concept id. I was looking at one of the example where there is one slide for Interrogation of CDM and Vocabulary, in the figure described there are 2 concepts and on Condition_Occurrence figure. My question is in the Condition_Occurrence figure, what do you mean by Condition_concept_Id and Condition_Source_Concept_ID and what do you mean by Standard_concept. Any help would be really great… I know these are basic questions, but as I said I just saw the OMOP CDM yesterday … Thanks in Advance … Ajinkya

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#2

Here is my naive answer. SDTM is designed for clinical trials, in which there is a relatively small number of variables, each of which is well characterized, and the expectation is 100 to 10,000 study subjects.

The OMOP CDM is designed to record health care data obtained from health records and from claims databases. It has to be comprehensive, covering all of medicine and covering all the nations of the world. So its definitions have to be broad and flexible. And it has to accommodate things like the notes and notes_nlp tables. Furthermore, it is designed to work efficiently with 100,000,000 patient records, which pushes toward simpler tables.

To handle the multiple nations and to also handle the diversity of vocabularies that people use, the CDM picks one vocabulary for each domain area and supplies mapping tables from whatever you currently store your data in to what the CDM wants. Then when you store your data in the table, you record both your original code (condition_source_concept_id) and the one that you map to (condition_concept_id). Normally during research you use the latter but you have the former available if you need it.

George

#3

Thanks @hripcsa for the response, so I understood about the SDTM and OMOP. Just to make myself understand with the example I can think of: if I have ICD9 code in my Source for Diabetes and I get the data into OMOP and map it to SNOMED, so my soruce_concept_id is the ID which is assigned to ICD9Code and my Concept_id would be of SNOMED code, is my understanding correct?

Thanks again for your response…
Ajinkya

#4

Correct on source_concept_id and concept_id, except that you store the OMOP code for each, not the native term. So source_value can get the actual ICD9 code (720.0), source_concept_id gets the OMOP code for that ICD9 code (44835004), and concept_id gets the OMOP code for the SNOMED code that it maps to (437082). We don’t bother storing the actual SNOMED code (9631008) or the name (Ankylosing spondylitis) because we can look them up.

George

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