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1 Introduction

This page describes the technical design of Lab2Zorg (Lab2Healthcare) as a subset of the Information standard lab exchange. This technical specification is implementer centric and complements the functional design. This page uses various terms as defined in the glossary (NL: Begrippenlijst). 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.

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 and one or more Observation.hasMember elements.
- Each .hasMember element references another Observation and the Observation with .hasMember elements thus serves as grouper for all Observation it references. Each Observation can be accessed individually. This is useful for panels and/or batteries of tests. This is what NL-CM:13.1.3 LaboratoryTest maps into.
- Note that while FHIR Observation also allows reference of resource types MolecularSequence | QuestionnaireResponse, there is no identified use case for that at 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 and one or more Observation.derivedFrom elements.
- Each .derivedFrom element references another Observation references related measurements the observation is made from. This is what NL-CM:13.1.33 RelatedResult::LaboratoryTestResult maps into.
- Note that while FHIR Observation also allows reference of resource types DocumentReference | ImagingStudy | Media | QuestionnaireResponse | MolecularSequence, there is no identified use case for those at time of writing.
Observation and one or more Observation.component elements.
- components 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 1 Observation with 3 components.

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 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.

Because of open world modeling, the cardinality of elements in the FHIR profiles can be less strict than the cardinalities in the ART-DECOR transactions. However, the latter cardinality is leading when it comes to exchanging building blocks in the context of a specific transaction. 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 either an 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.

Laboratory in FHIR R4 overview

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 LaboratoryTest
NL-CM:13.1.3 LaboratoryTest also maps into profile nl-core-LaboratoryTestResult Observation and may be referenced by 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 FHIR:.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.

2.2 Patient identification

This implementation guide assumes that the client system is able to make a connection to the right server that contains the patient's information. It does not provide information on finding the right server nor does it provide information about security. Moreover, each transaction is performed in the context of a specific (authenticated) patient, for whose context might have been established using the authentication mechanisms described in external specifications such as the MedMij 'Afsprakenstelsel' or through the usage of search parameters for patient identification. Each server is required to perform filtering based on the patient associated with the context for the request or based on the patient identification search parameters, so only the records associated with the authenticated patient are returned.

When patient identification requires the use of search parameters, the following search parameters SHALL be supported:

Patient: identifier
Observation: patient

An example of a request that retrieves all Observation resources of a patient with a fake BSN of 11122233:

GET [base]/Observation?patient:identifier=http://fhir.nl/fhir/NamingSystem/bsn|111222333

2.3 Resource identification

All profiles used within the information standard contain .identifier elements with a cardinality of 0..* because of open world modelling. However, all ART-DECOR transactions referenced within this IG assign a 1..1 R cardinality, meaning a stable identifier SHOULD be provided, or the DataAbsentReason extension if a value is missing. Identifiers SHALL contain both a .system and a .value.

Because in HL7v3 (CDA) an identifier can only be composed using OIDs, the .system SHALL be an OID to accommodate compatibility in transformations to and from FHIR. The Netherlands HL7v3 datatype II also defines additional restrictions on the maximum length of both @root and @extension (equivalent to respectively .system and .value in FHIR). For the same compatibility reasons, .system SHALL have a maximum of 128 characters and .value SHALL have a maximum of 64 characters.

Systems that encounter or resolve references, either logical or literal, in resources they receive, SHALL NOT rewrite these references to a copy of these resources (with http://nictiz.nl/fhir/StructureDefinition/ext-CopyIndicator present) they may store. This means that relative literal references may need to be rewritten to absolute ones. This also goes for included secondary resources in transactions.

3 Actors involved

Persons		Systems		FHIR Capability Statements
Name	Description	Name	Description	Name	Description
Lab Professional	The user of a LIS	LIS	Laboratory information system	CapabilityStatement: Lab2Healthcare-Results-RetrieveServe	Retrieve [LAB-LRR]/serve [LAB-LRB] lab results requirements
Lab Professional	The user of a LIS	LIS	Laboratory information system	CapabilityStatement: Lab2Healthcare-Results-SendReceive	Send [LAB-LRS]/receive [LAB-LRO] lab results requirements
Healthcare professional	The user of a XIS	XIS	(Any) Healthcare information system	CapabilityStatement: Lab2Healthcare-Results-RetrieveServe	Retrieve [LAB-LRR]/serve [LAB-LRB] lab results requirements
Healthcare professional	The user of a XIS	XIS	(Any) Healthcare information system	CapabilityStatement: Lab2Healthcare-Results-SendReceive	Send [LAB-LRS]/receive [LAB-LRO] lab results requirements

4 Use cases

4.1 Health professional orders lab tests and receives results

This use case will be added in a future release

4.2 Health professional retrieves lab results

4.2.1 Introduction

Healthcare professionals need to be able to retrieve laboratory results directly from a lab (LIS) or a secondary healthcare provider (XIS).

4.2.2 Actors

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

4.2.3 Invocations

4.2.3.1 XIS: request message

The request message represents an HTTP GET parameterized query from the XIS to the XIS/ LIS.

4.2.3.1.1 Trigger events

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

4.2.3.1.2 Message semantics

The XIS executes an HTTP GET conform to the FHIR RESTful and search specification against the XIS/LIS's Observation endpoint. This search query URL is configurable by the XIS and has the following format:

GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&patient.identifier=[system]|[value]{&[parameter(s)]&_include=[resource(s)]}

example

GET [base]/Observation?category=http://terminology.hl7.org/CodeSystem/observation-category|laboratory&patient.identifier=http://fhir.nl/fhir/NamingSystem/bsn|111222333&code=http://loinc.org|14683-7

Query parameters

patient, code and date

4.2.3.1.2.1 Expected actions

The XIS/LIS SHALL process the query to retrieve patient's (Laboratory results / Observation resources) and the included referenced resources.

4.2.3.2 XIS/LIS: response message

The XIS/LIS returns an HTTP Status code appropriate to the processing as well as a FHIR Bundle including the matching information.

4.2.3.2.1 Trigger events

The XIS/LIS completed the processing of the retrieve vaccinations request message.

4.2.3.2.2 Message semantics

The returned data to the XIS should conform to the profiles listed in the table below. The resources in the response message SHALL be a valid instance of these profiles. All resources SHALL include their related profile canonical URL in the .meta.profile element in order to show compliance.

FHIR Profiles	FHIR Resources	Based on zib (NL)	Based on zib (EN)
nl-core-LaboratoryTestResult	Observation	LaboratoriumTest	LaboratoryTest
nl-core-LaboratoryTestResult	Observation	LaboratoriumUitslag	TestResult
nl-core-LaboratoryTestResult.Specimen	Specimen	Monster	Specimen
nl-core-HealthProfessional-Practitioner	Practitioner	Zorgverlener	HealthProfessional
nl-core-HealthProfessional-PractitionerRole	PractionerRole	Zorgverlener	HealthProfessional
nl-core-HealthcareProvider-Organization	Organization	Zorgaanbieder	HealthcareProvider
nl-core-HealthcareProvider	Location	Zorgaanbieder	HealthcareProvider

4.2.3.2.3 Expected actions

The XIS SHALL process the results. The XIS SHOULD contain all the resources that match the query and all the reference resources that are included in the Bundle.

4.3 Health professional sends lab results to other health professional

4.3.1 Introduction

The functional design distinguishes two use cases where lab results may be sent with something else or separate. The process of 'sending' things in FHIR works by means of a RESTful 'create' action. You could create a single Observation on another system using POST Observation and the appropriate Observation in the request body. When you have multiple Observations to create, you could do that for every single Observation, or by means of a Bundle with all resources. This same Bundle approach works for one Observation too.

The added benefit from a Bundle lies in having a solution for all other resources you may want to send, e.g. MedicationRequest, and referenced resources, e.g. Patient and PractitionerRole | Practitioner | Organization. Sending the Observation without the resources it references would only work if the receiving server can resolve those. They should then already exist on that server, with references to them or they should be accessible on the source. Without access to the references in the Observation, the target server may not know which patient is involved or what lab this result came from.

4.3.2 Actors

Transaction group	Transaction	Actor	Role
Send laboratory results (PUSH)	Send laboratory results	LaboratoriumresultaatResultaatSturend Systeem [LAB-LRS]	Send lab results to the LAB-LRO
Send laboratory results (PUSH)	Receive laboratory results	LaboratoriumresultaatResultaatOntvangend Systeem [LAB-LRO]	Respond received lab results from the LAB-LRS

4.3.3 Invocations

4.3.3.1 XIS: request message

The send lab results request message uses the HTTP POST method on the target XIS's base. Note that lab results may or may not be sent in tandem with other resources like MedicationRequest. The same principles apply with or without these other resources. The server can only process the incoming request correctly if it understands what is being sent which includes being able to resolve references.

4.3.3.1.1 Trigger Events

This message is invoked when the XIS needs to send one or more lab results observations to another XIS.

4.3.3.1.2 Message Semantics

Because sending laboratory results will most likely consist of multiple Observations, a transaction operation is used. This allows for creating a set of resources in a single interaction and makes it possible to include referenced secondary resources if needed.

A transaction interaction is performed by an HTTP POST command as shown:

POST [base]

The body of the post submission is a Bundle with Bundle.type=transaction. Each entry carries request details (Bundle.entry.request) that provides the HTTP details of the action in order to inform the system processing the transaction or what to do for the entry. (Note: .request SHALL be present, even for the resources which aren't Observations. See the overarching principles for more information.)

Identification:

Sending systems SHALL have a stable identifier in the .identifier element for all Observation resources. Having stable identification is essential in detection of duplicates and potential clinical decision making issues deriving from duplicates. For more information on dealing with identifiers, see the general FHIR IG.

Links:

The laboratory result data sent to the XIS SHALL conform to the matching LaboratoryResult based profile. The table below lists profiles that represent applicable zibs for laboratory result information exchange.

FHIR Profiles	FHIR Resources	Based on zib (NL)	Based on zib (EN)
nl-core-Patient	Patiënt	Patient (M)	Patient
nl-core-HealthProfessional-Practitioner nl-core-HealthProfessional-PractitionerRole	Practitioner	Zorgverlener (M)	HealthProfessional
nl-core-laboratorytest	Observation	LaboratoriumUitslag(M)	LaboratoryTestResult

4.3.3.1.2.1 Expected Actions

On receipt of the submission, the XIS SHALL:

process creation of all Observation resources successfully or process no Observation
match Patient, Practitioner(Role), Organization to pre-existing resources on that server
- The server MAY update pre-existing information with the incoming information
- The server MAY keep its pre-existing matching resources as-is
- The server SHALL create new resources if no matching resource is found (unknown patient, new physician in otherwise known organization, etc.)
decide if any available Specimen resources are relevant
- If the server decides to ignore Specimen information, it SHALL not keep the Observation.specimen reference
respond using HTTP 200 and a Bundle with detail in case of success. See FHIR IG Handling Errors for response options in case of errors
- Note that the response Bundle with type transaction-response SHALL be specific about how the server handled the request Bundle.

4.3.3.2 XIS: response message

The XIS returns an HTTP Status code appropriate to the processing outcome and returns a Bundle, of type batch-response, that contains one entry for each entry in the request, in the same order, with the outcome of processing the entry.

4.3.3.2.1 Trigger Events

The XIS completed processing of the send laboratory results request message.

4.3.3.2.2 Message Semantics

The XIS SHALL return a Bundle with type set to batch-response that contains one entry for each entry in the request, in the same order, with the outcome of processing the entry.

A client may use the returned Bundle to track the outcomes of processing the entry, and the identities assigned to the resources by the server. Each entry element SHALL contain a response element which details the outcome of processing the entry - the HTTP status code, and the location and ETag header values, which are used for identifying and versioning the resources. In addition, a resource may be included in the entry, as specified by the Prefer header.

4.3.3.2.3 Expected Actions

The XIS server processes the results according to application-defined rules.

4.3.3.2.4 Handling Errors

The server may be unable to accept a Bundle due to errors or because of business rules (e.g. because of an unsupported code value in an Observation resource). Refer to the [FHIR:Vdraft_FHIR_IG_R4#Handling_errors#Handling_errors Handling Errors section] in the FHIR IG for more information.

4.4 Health professional reports result leading into a notification "new lab results" for subscribed healthcare professional(s)

DO

FHIR Lab2zorg V3.0.0

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