# FHIR : ValueSets, Concepts

### Specific FHIR concepts

FHIR expects to render data with codes in specified ValueSets

#### The concept\_fhir SQL table

This table is needed by our FHIR implementation to fasten how we render data to REST clients. We store a mapping between codes that appear in OMOP patient data tables (person, visit, ...) and the codes that FHIR expects to render in every Resource

| `source_concept_id` | `source_concept_code` | `source_concept_name` | `urce_vocabulary_reference`        | `target_concept_id` | `target_concept_code` | `target_vocabulary_reference`                 |
| ------------------- | --------------------- | --------------------- | ---------------------------------- | ------------------- | --------------------- | --------------------------------------------- |
| 12997538            | H72                   | Some description      | <http://valueset.com/somevalueset> | 9845131             | KYVV                  | <http://randomvalueset.com/someothervalueset> |

#### FHIR constraints on Resource fields codes

As [described in the FHIR standard](https://www.hl7.org/fhir/terminologies.html#strength), there are 4 different kind of constraints on ressource fields codes:

| Constraint | Description                                                                                      | Example                                                                                                                                                                                                               |
| ---------- | ------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| required   | Code is required to be from a specified ValueSet                                                 | Patient.gender code is **required** to be a code from [http://hl7.org/fhir/ValueSet/administrative-gender&#xD;](<http://hl7.org/fhir/ValueSet/administrative-gender&#xD;&#xA;>)                                       |
| extensible | Code is required to be from a specified ValueSet but if needed you can add your own codes        | Patient.maritalStatus code is **required** to be a code from the [http://hl7.org/fhir/ValueSet/marital-status](<http://hl7.org/fhir/ValueSet/marital-status&#xD;&#xA;>) **but you can extend it with your own codes** |
| preferred  | it is encouraged to use a code from a ValueSet specified by the standard but it is not mandatory | Patient.communication.language is **encouraged** to be from the [http://hl7.org/fhir/ValueSet/all-languages](<http://hl7.org/fhir/ValueSet/all-languages&#xD;&#xA;>) **but you can use your own ValueSet**            |
| example    | Code can be from any ValueSet                                                                    | Encounter.type can be from [http://hl7.org/fhir/ValueSet/encounter-type&#xD;](<http://hl7.org/fhir/ValueSet/encounter-type&#xD;&#xA;>) or any other                                                                   |


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