How can I return type(s) of FHIR Resource based on snomed code?

[dmpour23]

Is there a way to return the resource type of FHIR resource or a list of types (Patient,Observation,Medication) based on SNOMED code?

[kaicode]

I'm not sure if I understand the question...

Are you asking if it's possible to go from a SNOMED Code like 446141000124107 |Identifies as female gender (finding)| and return the FHIR resource type Patient?

Another example could be a medication SNOMED CT code like 322236009 |Product containing precisely paracetamol 500 milligram/1 each conventional release oral tablet (clinical drug)| and return FHIR resource type Medication?

[dmpour23]

Yes, I have a (large) set of snomed codes and I would like to map them to fhir resource type. I would like if possible to automate this process by calling an API and then manually going through and verifying its outputs.

[kaicode]

The SNOMED codes on their own, without any information model, do not tell the whole story. There are also many overlaps where the same SNOMED codes are used in different resources to describe different scenarios.

It's theoretically possible to do some of what you are asking but it would be very error prone. The FHIR resources created would not be suitable to support clinical care because too many assumptions would have to be made during the transformation. The generated FHIR resources might be okay for research purposes but that's down to your judgement.

There is no off the shelf solution for this so some scripting would be needed.

Rough solution design:

1. Define sets of SNOMED codes that map to specific fields within FHIR resources. Could reuse the ValueSets from a FHIR IG.
2. For each incoming SNOMED code use a terminology server to test if it falls within any of the ValueSets with the validate-code operation.
3. If you find a match create the FHIR resource adding the SNOMED code. Many of the resource fields will need to be pre-filled with assumed values.

For example, codes that are descendants of 404684003 |Clinical finding (finding)| are commonly used for the Observation code. However you would need to know the subject and other fields, which do not come from the SNOMED code. Perhaps you could assume that the subject is the Patient, but it really depends on the source of the data. Clinical finding concepts are also used for the Condition resource and it's not possible to determine which resource should be used from the SNOMED code.

I think you need more context than just the SNOMED code in order to create FHIR resources.

[dmpour23]

Thanks for you quick response I agree. I needed a quick and most likely "dirty' approach for example to fill possible resource type such as shown in column 4 below. i.e part of step one. "Define SNOMED code that map to specific fields within FHIR resources."

DEMOGRAPHICS	AGE	age at first diagnosis defined as difference between date of first diagnosis and date of birth	Observation.valueQuantity	LOINC	30525-0
DEMOGRAPHICS	SEX	sex	Patient.gender
SOCIOECONOMIC	EDUCATION	level of education	Observation.valueString
CONDITIONS	DIABETES	presence/absence of diabetes	Condition.code	SNOMED	73211009
CONDITIONS	DYSLIPIDEMIA	presence/absence of dyslipidemia	Condition.code	SNOMED	55822004

[kaicode]

The FHIR CodeSystem subsumes operation could be helpful. To check if each code is one of the types you have defined.
https://hl7.org/fhir/R4B/codesystem-operation-subsumes.html

For example to check if a code is a type of diabetes:
GET [base]/CodeSystem/$subsumes?system=http://snomed.info/sct&codeA=73211009&codeB=1481000119100

Where [base] is a FHIR Terminology Server that supports $subsumes. For example you could use Snowstorm Lite.