Question:

Do you know if there is an HL7  official list of vendors supporting the HL7 FIHR terminology service?
Also, are there any plans to certify HL7 FHIR terminology services?

Answer:

There’s no official list. The nearest we get to maintaining a list was in this wiki page, but the specific list seems to have fallen off. So here’s my list:

• Ontoserver – official terminology service for Australia. Looks like it;s on the path to being adopted in other countries as well
• Apelon DTS – open source, and a full blown terminology service that is filling out their FHIR API
• Art-Decor – provides FHIR API to the content in art-decor
• Terminz – focused on providing terminology services in NZ
• VSAC – provides some FHIR terminology services for the value sets already in VSAC
• HAPI – provides some terminology services but I’m not sure how complete and tested this is
• FHIRServer (my server)

Of these, I believe that the most thoroughly tested (at least on the FHIR API side) are Ontoserver and my server. My server runs tx.fhir.org which provides terminology services across the public FHIR community, but needs a lot of work to turn into a general purpose server. Ontoserver is a general purpose server and is very thoroughly tested through the Australian NCTS process.

We’ve talked about certifying terminology services, and we’re getting to the point of stability where it’s time to do that. HL7 hasn’t done that before, and we don’t know whether we should, or IHE should. But IHE hasn’t done testing on specifications they don’t own before, and the terminology service vendors haven’t decided whether they see a market advantage in certification yet (and how much certification $$ is viable) – so it’s basically an open question right now.

Question:

My team is currently working with FHIR DSTU2, and part of the project that we are working on requires  SMOKING information, particularly the date the patient started smoking.  Part of this work is also mapping this particular information to LOINC, and basically our issue is that we are unable to find anything that refers to a patient’s smoking start date in LOINC.  What would be your suggested work around for the above?

We did find quit date, which good – just not start date.

Answer:

Well, there’s no LOINC code to match 74010-0 (Date quit tobacco smoking). So the best option is to make up your own code, and propose that LOINC add a matching code, then change to use that once that’s done.

You can propose new LOINC codes here: https://loinc.org/submissions/

Question

What is the relationship between FHIR Documents and  composition resources? Meaning, what is the best way to capture/store in FHIR, documents that are not necessarily related to clinical info (file, images, file reference links to external content systems etc)

If I have several documents that need to be associated to a patient and organizations and was looking for your thoughts on best practices you have seen

Answer

Documents like this – files, images, reference links to content systems – these are best handled using DocumentReference.  Composition is used for documents that have tightly controlled content. a mix of narrative and data.

Question

What has your experience been with developers, developing on a FHIR model that requires FHIR resources — but also has a need for non-standard FHIR data (something like supply chain data or Blockchain external hashed data). Is the recommendation to shoe horn this into extensions  or have data models that live side-by-side with FHIR?

Answer

There’s no single answer to this question, because it depends on the other kind of data. Generally, there’s 3 approaches I’ve seen:

1. Use extensions in existing resources (particularly Basic). This approach is only good while the extensions are pretty narrow and limited, and closely related to the existing FHIR functionality
2. Use some other content model, and figure out how the functionality links. This approach is good where there is another content model. For example, in my server, I use SCIM for managing the user accounts. I use the SCIM content to link a user account to a FHIR resource like “Patient” so that I know which patient the user represents (if any) and I refer to the SCIM user identity in AuditEvent resources (as a URL)
3. Make up your own content but follow the FHIR patterns – effectively, custom FHIR resources. Use extensions to reference them. This approach is good where you have quite a bit of content/functionality, but there’s no external standard to follow

Which is best depends on what you’re doing.

A note about the custom resources idea: this is legal – you can do whatever you want with the names the FHIR doesn’t define. e.g. [base]/User. And if you choose to put something there, that happens to look a bit like a FHIR resource.. that’s still whatever you want. But things like ‘can I describe it from the CapabilityStatement’ and ‘can I search into the space’ are not technically legal, and there’s always a risk that HL7 will use the name in the next version of FHIR, making your solution locked in to being non-conformant. We’ve investigated making some policy around these questions to make custom resources manageable, but we’ve never managed to get the energy to push agreements over the line.

Question:

Does FHIR support API to update metadata of resource? I specifically ask for update of tags associated with a resource, e.g., adding (incl. overwriting) a tag, delete a tag

Answer:

Yes. See the operations $meta, $meta-add and $meta-delete

Question:

How to extend severity in AllergyIntolerance resource.  Is the following resource where severity is extended done correctly?

<AllergyIntolerance xmlns="http://hl7.org/fhir">
  <id value="uWErIN0G0" />
  <recordedDate value="05/10/1980" />
  <patient>
    <reference value="Patient/DFQA_ghn000003" />
    <display value="Newman, Alice Jones" />
  </patient>
  <substance>
    <coding>
      <system value="RxNorm" />
      <code value="1659592" />
    </coding>
    <text value="ampicillin-sulbactam" />
  </substance>
  <status value="confirmed" />
  <event>
    <manifestation>
      <coding />
      <text value="urticaria (hives)" />
    </manifestation>
    <severity>
      <extension url="http://phinvads.cdc.gov/vads/ViewValueSet.action?oid=2.16.840.1.113883.3.88.12.3221.6.8">
        <valueCodeableConcept>
          <coding>
            <system value="" />
            <code value="371923003" />
            <display value="mild to moderate" />
          </coding>
        </valueCodeableConcept>
      </extension>
    </severity>
  </event>
</AllergyIntolerance>

Answer:

Severity is a code, with cardinality 0..1 and a required binding to mild | moderate | severe. You can replace the code with an extension, as is done here, so that part is valid. But it’s much better to provide both a code out of the defined choices, so that systems that only know those choices can process the information correctly, while those that know the refined list can process the refined list:

    <severity value="mild">
      <extension url="http://phinvads.cdc.gov/vads/ViewValueSet.action?oid=2.16.840.1.113883.3.88.12.3221.6.8">
        <valueCodeableConcept>
          <coding>
            <system value="" />
            <code value="371923003" />
            <display value="mild to moderate" />
          </coding>
        </valueCodeableConcept>
      </extension>
    </severity>

Aside: you could map this code to either mild or moderate, yes. Choosing either is better than choosing neither.

There’s several other issues here, though:

• The URL given that identifies the extension actually identifies the value set, not the extension (aka the data element). The correct thing to do would be to define an extension that use the value set (see at the bottom of the post)
• According to the value set definition, this is a SNOMED CT code, and the system should be filled out
• the recorded date format is not a valid XML date
• the system for RxNorm is not correct
• manifestation coding can’t be empty

Here it is corrected:

<AllergyIntolerance xmlns="http://hl7.org/fhir">
  <id value="uWErIN0G0" />
  <recordedDate value="1980-10-05" />
  <patient>
    <reference value="Patient/DFQA_ghn000003" />
    <display value="Newman, Alice Jones" />
  </patient>
  <substance>
    <coding>
      <system value="http://www.nlm.nih.gov/research/umls/rxnorm" />
      <code value="1659592" />
    </coding>
    <text value="ampicillin-sulbactam" />
  </substance>
  <status value="confirmed" />
  <event>
    <manifestation>
      <text value="urticaria (hives)" />
    </manifestation>
    <severity>
      <extension url="http://example.org/fhir/StructureDefinition/my-extension">
        <valueCodeableCoding>
          <system value="http://snomed.info/sct" />
          <code value="371923003" />
          <display value="mild to moderate" />
        </valueCodeableCoding>
      </extension>
    </severity>
  </event>
</AllergyIntolerance>

With an associated Extension definition:

<?xml version="1.0" encoding="utf-8"?>
<StructureDefinition xmlns="http://hl7.org/fhir">
  <meta>
    <lastUpdated value="2017-07-12T07:05:27.311+10:00" />
  </meta>
  <url value="http://example.org/fhir/StructureDefinition/my-extension" />
  <name value="RefinedSeverity" />
  <status value="draft" />
  <date value="2017-07-12T07:02:31.9614187+10:00" />
  <publisher value="Health Intersections" />
  <description value="My definition for FHIR extension" />
  <purpose value="an extension" />
  <fhirVersion value="3.0.1" />
  <kind value="complex-type" />
  <abstract value="false" />
  <contextType value="resource"/> 
  <context value="AllergyIntolerance.event.severity"/> 
  <type value="Extension" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension" />
  <derivation value="constraint" />
  <differential>
    <element id="Extension">
      <path value="Extension" />
      <definition value="This is a description of the level of the severity of the problem." />
    </element>
    <element id="Extension.url">
      <path value="Extension.url" />
      <fixedUri value="http://example.org/fhir/StructureDefinition/my-extension" />
    </element>
    <element id="Extension.value[x]:valueCoding">
      <path value="Extension.valueCoding" />
      <sliceName value="Severity" />
      <type>
        <code value="Coding" />
      </type>
      <binding>
        <strength value="required" />
        <description value="This is a description of the level of the severity of the problem." />
        <valueSetUri value="http://phinvads.cdc.gov/vads/ViewValueSet.action?oid=2.16.840.1.113883.3.88.12.3221.6.8" />
      </binding>
    </element>
  </differential>
</StructureDefinition>