FHIR Implementation Guide Lab2patient V1.0.0 - alpha

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This IG is currently under development and can not be considered stable and ready for use.


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1 Introduction

Go to functional design

This page describes the technical design of Lab2patient (L2P) as a subset of the Information standard lab exchange (Dutch: Labuitwisseling or abbreviated to LU). This technical specification is implementer centric and complements the functional design. This page uses various terms as defined in the glossary.

1.1 Disclaimers

This page implements general principles applicable to FHIR as outlined by a central FHIR IG for R4. Please make sure you familiarize yourself with both the functional design and the FHIR IG for full appreciation of the context of this page.

This FHIR Implementation Guide assumes that systems (XIS) are able to make a connection to the right systems. It does not provide information on finding the right XIS nor does it provide information about security including authentication and authorization. Finding the right system, and security aspects of the connection, are dealt with by the infrastructure. Any relevant infrastructure is expected to have a framework in place to deal with this. The only assumption/requirement for an infrastructure is that this allows RESTful FHIR-based exchange as specified here.

2 Boundaries and relationships

2.1 Overview of relationships between FHIR resources

Laboratory results in FHIR R4 overview

2.2 Mappings between profiles and data set

Each transaction starts with links to the functional definition in an ART-DECOR publication and references one or several FHIR profiles. Where the functional definition contains all specific data elements for the transaction (prefixed with ‘lu-concept-v2’), the FHIR profiles only contain a mapping to these data elements that do not have a dependency on a zib counterpart. For example: ‘lu-concept-v2-4266’ (Specimen) has a relation with the zib element with id ‘NL-CM-13.1.2’, therefore no mapping with ‘lu-concept-v2-4266’ can be found in the profiles. On the other hand, ‘lu-concept-v2-4296’ (LaboratoryResultIdentification) has no relation with a zib element, therefore a mapping can be found in the relevant FHIR profile.

Cardinalities in FHIR profiles may be less strict than the ART-DECOR definitions. In this IG, transaction-level cardinalities take precedence. For example: in the nl-core-LaboratoryTestResult profile, .performer has a core cardinality of 0..*, while in both the 'Send laboratory results' and ‘Serve laboratory results’ ART-DECOR transactions, the Performer element has a cardinality of 1..1 M. Therefore, .performer is expected to be filled with a reference to an nl-core-HealthcareProvider-Organization resource.

Each transaction contains a Patient building block with cardinality 1..1 M. This patient is the subject of all other building blocks in the transaction, although no explicit relation exists in the data set. Therefore, a reference to a Patient resource conforming to the nl-core-Patient profile is expected in .subject of each FHIR instance of each building block.

The single zib LaboratoryTestResult consists of objects that in FHIR are represented using different (instances of) resources:

  • NL-CM:13.1.1 LaboratoryTestResult maps into profile nl-core-LaboratoryTestResult Observation and has .hasMember relationships with individual NL-CM:13.1.3 LaboratoryTests.
    • Note that this level only exists when LaboratoryTestResult contains NL-CM:13.1.4 PanelOrBattery. The concepts NL-CM:13.1.7 ResultType, NL-CM:13.1.5 Comment, and NL-CM:13.1.6 ResultStatus are not mapped in the absence of NL-CM:13.1.4 PanelOrBattery.
  • NL-CM:13.1.3 LaboratoryTest also maps into profile nl-core-LaboratoryTestResult Observation and MAY be referenced by a different Observation.hasMember containing NL-CM:13.1.1 LaboratoryTestResult.
  • NL-CM:13.1.2 Specimen maps into profile nl-core-LaboratoryTestResult.Specimen Specimen.
    • Note that there could be multiple instances of Specimen: one for the main NL-CM:13.1.16 SpecimenMaterial, and one per isolated NL-CM:13.1.22 Microorganism with a .parent relationship to the main specimen.
  • NL-CM:13.1.29 SpecimenSource maps into profile nl-core-LaboratoryTestResult.Specimen.Source Device. This is a special case where the specimen did not come from the Patient directly.

2.3 FHIR relationship structures

Many laboratory results have important relationships to other observations and need to be grouped together. The FHIR specification defines several structures to do this:

  • Observation.hasMember
    • Each .hasMember element references another Observation and the Observation with .hasMember elements thus serves as grouper for all Observations it references. Each Observation can be accessed individually. This is useful for panels and/or batteries of tests.
    • Note that while FHIR Observation also allows references to resource types MolecularSequence and QuestionnaireResponse, there is no identified use case for that at the time of writing.
    • An Observation without .hasMember elements is expected to be an individual result and has a value when one can be/is determined.
  • Observation.derivedFrom
    • Each .derivedFrom element references another Observation references related measurements the observation is made from.
    • Note that while FHIR Observation also allows references to resource types DocumentReference, ImagingStudy, Media, QuestionnaireResponse and MolecularSequence, there is no identified use case for those at the time of writing.
  • Observation.component
    • .component elements of an Observation are not accessible individually. Whenever you access the Observation, you also access all its components. This is mostly useful when certain context is provided around the result. For lab observations this is expected to be less common. An example outside of the lab realm could be BloodPressure where systolic, diastolic, and cuff size are all in one Observation with 3 components.

2.4 Resource identification

ART-DECOR transactions define a stricter cardinality of 1..1 R for resource identifiers. Therefore:

  • A stable identifier SHOULD be provided for each resource.
  • If no identifier value is available, the DataAbsentReason extension SHOULD be used.
  • Identifiers SHALL contain both a .system and a .value.

For compatibility with HL7v3 (CDA), where identifiers can only be represented as OIDs:

  • The .system SHALL be an OID to ensure compatibility in transformations to and from FHIR.
  • The .system SHALL have a maximum of 128 characters.
  • The .value SHALL have a maximum of 64 characters.

Regarding reference handling:

2.5 FHIR Profile Package

All use cases in this specification depend on the same set of FHIR profiles. FHIR profile package for Lab2Patient is currently in development. The table below lists profiles used within the framework of Lab2Zorg (Lab2Healthcare) that represent applicable zibs for laboratory result information exchange.

FHIR Profile FHIR Resource Based on zib
nl-core-LaboratoryTestResult Observation LaboratoryTestResult
nl-core-LaboratoryTestResult.Specimen Specimen
nl-core-LaboratoryTestResult.Specimen.Source Device
nl-core-Patient Patient Patient
nl-core-HealthcareProvider-Organization Organization HealthcareProvider

3 Actors involved

Actors Systems FHIR CapabilityStatements
Name Description Name Description Name Description
Patient The user of a personal healthcare environment. PHR Personal health record CapabilityStatement: Lab2Healthcare-Results-RetrieveServe Retrieve [LAB-LRR-PGO]/serve [LAB-LRB-PGO] lab results requirements.
Lab Professional The user of a LIS LIS Laboratory information system

4 Use cases

4.1 Patient retrieves laboratory results in their PGO

4.1.1 Introduction

This FHIR Implementation Guide assumes that the PHR system is able to make a connection to the right LIS that contains the patient's information. It does not provide information on finding the right LIS nor does it provide information about security. Moreover, each transaction is performed in the context of a specific authenticated patient, for whose context (token) has been established using the authentication mechanisms described in the 'Afsprakenstelsel'. Each XIS Gateway is required to perform filtering based on the patient associated with the context for the request, so only the records associated with the authenticated patient are returned. For this reason, search parameters should not be included for patient identification.

4.1.2 Actors

Transaction group Transaction Actor Role
Retrieve laboratory results (PULL) Retrieve laboratory results request LaboratoriumresultaatResultaatRaadplegend Systeem [LAB-LRR-PGO] Send a query to the LAB-LRB-PGO to retrieve lab results
Retrieve laboratory results response LaboratoriumresultaatResultaatBeschikbaarstellend Systeem [LAB-LRB-PGO] Respond to a query from the LAB-LRR-PGO to retrieve lab results

4.1.3 Invocations

4.1.3.1 LAB-LRR-PGO: request message

The request message represents an HTTP GET parameterized query from the PHR (LAB-LRR-PGO) to the LIS (LAB-LRB-PGO).

4.1.3.1.1 Trigger events

When the PHR wants to obtain laboratory results, it issues a retrieve laboratory results request message.

4.1.3.1.2 Message semantics

The PHR (LAB-LRR-PGO) executes an HTTP GET conforming to the FHIR RESTful and search specification against the LIS's Observation endpoint. Laboratory results are all under the .category observation, using query parameter category as token.

Basic query syntax

GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory

Examples

Parameter values have not been uri escaped in these examples for readability. This is likely necessary in practice.

UitvouwenGet all lab results of type 14683-7 (LOINC)
GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7
UitvouwenGet all lab results of type 14683-7 (LOINC) since March 12, 2022
GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7&date=gt2022-03-12
UitvouwenGet all lab results of type 14683-7 (LOINC) since March 12, 2022 but before June 7, 2022
GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7&date=gt2022-03-12&date=lt2022-06-07
UitvouwenGet all lab results of type 14683-7 (LOINC) and/or 3583 (NHG)
GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7,https://referentiemodel.nhg.org/tabellen/nhg-tabel-45-diagnostische-bepalingen|3583
UitvouwenGet latest lab result of type 14683-7 (LOINC)
GET [base]/Observation/$lastn?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7
UitvouwenGet latest 5 lab results of type 14683-7 (LOINC)
GET [base]/Observation/$lastn?max=5&category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&code=http://loinc.org|14683-7
UitvouwenGet latest lab result of any type
GET [base]/Observation/$lastn?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory
4.1.3.1.2.1 Expected actions

The LIS (LAB-LRB-PGO) SHALL process the query to retrieve laboratory results.

4.1.3.2 LAB-LRB-PGO: response message

The LIS (LAB-LRB-PGO) returns an HTTP Status code appropriate to the processing as well as a FHIR Bundle including the matching information. Refer to the generic FHIR IG for more information on handling errors and status codes. Not finding a match based on stated parameters does not constitute an error.

4.1.3.2.1 Trigger events

The LIS (LAB-LRB-PGO) completed the processing of the retrieve laboratory results request message.

4.1.3.2.2 Message semantics

The LIS (LAB-LRB-PGO) SHALL process the request and, unless an error is found, respond with a Bundle resource of type searchset. Each Observation matching the request SHALL be marked with .entry.search.mode=match. Each otherwise included resource SHALL be marked with .entry.search.mode=include. If the searchset bundle contains less matching resources than the actual total set, then:

  • the Bundle.link that holds the self link, SHOULD include the _count parameter to inform the client of what max was applied
  • an OperationOutcome SHOULD be included marked with .entry.search.mode=outcome.

The resources in the response Bundle SHALL be a valid instance of their stated profile. All resources SHALL include their related profile canonical URL in the .meta.profile element in order to show compliance. The exception is the OperationOutcome resource for which there is no profile in this specification.

Example searchset Bundle

UitvouwenXML contents for searchset Bundle
<Bundle xmlns="http://hl7.org/fhir">
    <id value="1"/>
    <type value="searchset"/>
    <total value="3"/>
    <link>
        <relation value="self"/>
        <url value="http://example.org/fhir?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&amp;patient:identifier=http://fhir.nl/fhir/NamingSystem/bsn|111222333&amp;code=http://loinc.org|14683-7"/>
    </link>
    <entry>
        <fullUrl value="https://example.org/fhir/Observation/1"/>
        <resource>
            <Observation>
                <!--  -->
            </Observation>
        </resource>
        <search>
            <mode value="match"/>
        </search>
    </entry>
    <entry>
        <fullUrl value="https://example.org/fhir/Observation/2"/>
        <resource>
            <Observation>
                <!--  -->
            </Observation>
        </resource>
        <search>
            <mode value="match"/>
        </search>
    </entry>
    <entry>
        <fullUrl value="https://example.org/fhir/Observation/3"/>
        <resource>
            <resource>
                <Observation>
                    <!--  -->
                </Observation>
            </resource>
        </resource>
        <search>
            <mode value="match"/>
        </search>
    </entry>
    <entry>
        <fullUrl value="https://example.org/fhir/Specimen/1"/>
        <resource>
            <Specimen>
                <!--  -->
            </Specimen>
        </resource>
        <search>
            <mode value="include"/>
        </search>
    </entry>
    <entry>
        <fullUrl value="https://example.org/fhir/Patient/1"/>
        <resource>
            <Patient>
                <!--  -->
            </Patient>
        </resource>
        <search>
            <mode value="include"/>
        </search>
    </entry>
    <entry>
        <fullUrl value="https://example.org/fhir/Organization/1"/>
        <resource>
            <Organization>
                <!--  -->
            </Organization>
        </resource>
        <search>
            <mode value="include"/>
        </search>
    </entry>
</Bundle>

Example OperationOutcome

UitvouwenXML contents for OperationOutcome
<OperationOutcome xmlns="http://hl7.org/fhir">
    <id value="size-exceeded-1"/>
    <issue>
        <severity value="warning"/>
        <code value="too-costly"/>
        <details>
            <text value="Resultaat was 3000, wat meer is dan het maximum van 1000"/>
        </details>
    </issue>
</OperationOutcome>
4.1.3.2.3 LAB-LRB-PGO: Expected actions

The LIS (LAB-LRB-PGO) SHALL process the response Bundle in accordance with the intentions of the trigger event that caused the retrieve. Actions may include discrete rendering on screen or in context with other information, triggering alerts on trends, ordering of (other) tests and more.