Why is this needed

• HL7V2 is widely used in many places

• Very dominant in Australia Lab/Clinical/Radiology

• Continues in Lab in most places

• Complexity of data continues to grow

• Much more than name=value line items

• Clinical Decision Support needs fine grained access to data

• VMR project requires access to complex V2 data

• In Australia VMR depends on access to clinical data in V2

• Structuring of Data in V2 done on ad hoc basis

• Need reliable access to hierarchical data structures

Example Report Types

• Atomic histopathology reports under development

• • Complex microbiology with sensitivities for multiple organisms

• VMR data

• • Problem lists, Family History etc

• DCM data

• Assessments and scales

• Pedigree data

• PHER

Possible Options

• OBR Segments as section headers

• • Genomics messages

• OIDs in OBX SubID

• • Requires external documentation

• • Hierarchy still problematic (see VMR draft)

• Structured OBX SubID

• • Allows hierarchy to be developed

• • Can use templates eg ISO 13606-2

• • Needs Template to describe Structure ideally, but can be described in narrative

OBR as section headers - Potential issues

• OBR segments are “Document Headers”

• Traditionally every OBR indicates a standalone document

• Only allows one level of hierarchy

• No nesting ability

• Message becomes document

• Grouping of OBR segments at message level

• • Invalidates HL7 queries QRY/ORF

• • Cannot be used in Orders or Medication Messages

• Many existing Systems display each OBR on single page

• What does the V2 standard say?

In Summary OBR is defined as a report header and not a section header. While it is possible to do single level structuring using the message as the document this breaks many other parts of V2 including ORF style queries and restricts the places you can use the structured data. It excludes its use in any order type in particular.

OBX Hierarchy with SubID - Many Advantages

• Uses “Dotted” Sub-ID (OBX-4)

• Examples of this in existing standards

• Allows extensive nesting of OBX segments

• Permits efficient sparse tree algorithms

• Permits reordering of OBX segments for display purposes

• Backward compatible

• Can be used wherever a repeating OBX group found

• • Orders, medication, vaccination messages

• Complexity only limited by field length restrictions

• Used in trials of VMR in Australia

• Used for lab reporting in trial sites in Australia

• Can be combined with Metadata specifications

• Creates DCM capable systems

• • EN 13606-2 used in trial sites

• Used to transmit VMR (Virtual Medical Record) in trial sites

What does the standard say about this

From Chapter 7 of HL7 V2 standard - an Example of Dotted OBX Sub ID

Example using LOINC Template

This is the LOINC Panel in this case represented using a EN 13606 Archetype

We add some Terminology binding

Here is the HL7 that matches the structure of the Panel using the OBX-4 SubID for hierarchical structuring

OBX Section Headers

• Primarily for Human Display

• ST or CE datatypes

• Name=Value

• • Section Header(The name) = Name of Section Header (The value)

• • Ideally should have specific LOINC code or name

OBX|13|CE|15431-0^^LN^CLUSTER^^EN 13606|1.1.13|24326-1^Electrolytes^LN

Currently using LOINC comment code and EN13606 Node name This suppressing display of OBX-3 in Australian Implementations

In this example an OBR could be used to create 2 separate documents, although the intention here is to view them together. In more complex examples we clearly desire a single document with sub sections, rather than sub documents. In complex models can be 10-20 section headers present in single document.

OBR vs OBX Section Headers

• OBR Headers work when data divided into Documents

• • Less suitable when have hierarchy within documents

• • Not suitable for ORF/Orders

• OBX Section Headers/Dotted Sub-ID

• • Allow hierarchy within documents

• • OBX Sub-ID allows complex hierarchy

• • When provide Metadata via templates

• • • Allows semantic interoperability

• • • Allows Decision support at higher level

• • • Allows V2 and CDA versions of Data

• • • Works with EN 13606-2

• • • • Still no EN 13606 messaging specification

• • • • Allows HL7 V2 to fulfil this role

• • Backward compatibility

• • Could define CCD profile in HL7 V2

• • Allows development of VMR in HL7 V2