DRAFT Implementation Guide

This is for collaboration and discussion purposes and is subject to change.

North West Genomic Medicine Service Alliance, published by NHS North West GMSA. This guide is not an authorized publication; it is the continuous build for version 0.0.1 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/nw-gmsa/LTW/ and changes regularly. See the Directory of published versions

Overview

Domain Archetype

Domain Archetype is the result of a collaboration process which aims to form a series of common archetypes within a domain (the domain in this case is Genomics). The initial format for this archetype is often a spreadsheet that is expressed in an electronic format. The format we are using in this guide is HL7 FHIR Questionnaire, other formats can be used such as openEHR Archetype (see Genomic Variant Result)

For communication between different systems, these archetypes are mapped to a Common Information Model.

Domain Archetype

Common Information Model

The domain archetypes are implemented via a Canonical Data Model, which is common across all technical formats (i.e. HL7 v2 and HL7 FHIR) and is described using HL7 FHIR.

Elements from NHS England FHIR Genomics Implementation Guide have been incorporated into this guide, in particular the use of NHS Data Model and Dictionary Model identifiers and other identifiers already present in HL7 v2 OML and ORU. See Identities and Codes for more details.

Enterprise Canonical Data Model

Identities and Codes

Both domain archetypes have a very strong focus on the use of Correlation Identifier (Enterprise Integration Patterns) or Rule 3: Reference Other Aggregates by Identity (Implementing Domain Driven Design), which is also consistent with IHE/HL7 concepts of Bounded Context (martinfowler.com)

In practice this means, the following FHIR resources will have the following identifiers within the IHE Laboratory Testing Workflow domain:

• ServiceRequest
  • Placer Order Number
  • Filler Order Number
  • Placer Group Number
  • Accession Number
• Specimen
  • identifier
  • Accession Number
• DiagnosticReport
  • identifier
  • Filler Order Number
  • Accession Number
• Patient (not strictly within the domain but included for HL7/IHE/NHSE compatability reasons)
  • NHS Number
  • Medical Record Number
• Encounter
  • Visit Number

This includes making use of FHIR Identifier assigner.identifier.value (HL7 v2 Assigning Facility in a variety of ID types) to distinguish these identifiers between different organisations, the recommendation is to use ODS Code, e.g.

    {
      "type" : {
        "coding" : [
          {
            "system" : "http://terminology.hl7.org/CodeSystem/v2-0203",
            "code" : "ACSN"
          }
        ]
      },
      "value" : "1001166717",
      "assigner" : {
        "identifier" : {
          "system" : "https://fhir.nhs.uk/Id/ods-organization-code",
          "value" : "699X0"
        }
      }
    }

References to other domains

Is present around Organisation, Practioner and PractitionerRole. NHS England has expressed a preference to use NHS England Identifiers, these are:

• Organization
  • ODS Code
• Practitioner
  • Practitioner Identifiers (GMP and GMC Numbers)
• PractitionerRole
  • ODS Code
  • Practitioner Identifiers

Codes or Resources

This is for discussion, this applies to FHIR resources identified as not being entities (and the use of identifier is not mandatory). These include:

• Observation
• Condition

In FHIR the codes for these will be CodeableConcept (HL7 v2 CE Data Types). It is excepted NHS England will

• express a preference towards SNOMED CT
• use FHIR Resources to represent these.

The use of FHIR resources for data which is currently HL7 v2 CE Data Type may need to be questioned. For example mapping of HL7 v2 ORC-16 is to ServiceRequest.requestCode according to ServiceRquest - HL7 v2 Mapping, this is a v2 CE to FHIR CodeableConcept conversion. Curently this is stated as an implied ServiceRequest.requestReference mapping (ISSUE link: NHS England Developer Community Genomics Order Management Service - FHIR ServiceRequest reason)