The document outlines the structure and persistence strategies for OpenEHR data objects related to electronic health records (EHR). It distinguishes between event-compositions that capture specific clinical encounters and persistent compositions that maintain stateful summaries, updating throughout a patient's lifetime. The document emphasizes the importance of categorization and versioning in managing clinical data effectively, highlighting key components like metadata, unique identifiers, and the significance of archetypes and templates in defining relationships between entries.

1. Dr Ian McNicoll
Composition Persistence
Strategies

2. openEHR data objects
EHR
COMPOSITION = ‘Nursing Observations
SECTION Vital signs
ENTRY Blood P.
Systolic
Diastolic
ENTRY Pulse
Rate
Rhythm
General appearance
Skin colour
Behaviour
Skin turgor
Capillary
Return
Hydration
SECTION = ‘Other obs’
ehr_id = 5c8a8636-bc98-4441-abd5-e9cf396e8833
134 mmHg
86 mmHg
134 mmHg
Irregular
Jaundiced
Normal
Reduced
30s

3. Composition - the document container
Root ‘document’ for clinical data
Carries most key medico-legal metadata
composer (clinical_author), start_time, end_time
organisation, clinical setting
All recorded patient data saved inside a Composition
Carries unique ID
UID::serverID::Version_Suffix
5c8a8636-bc98-4441-abd5-e9cf396e8833::ripple_osi.ehrscape.c4h::1
Versioned
All changes will create a new version

4. ‘Event’ category
Each time new data is committed, a completely new
composition instance is created
Lab reports, nursing observations, doctor encounter
5c8a8636-bc98-4441-abd5-e9cf396e8833::ripple_osi.ehrscape.c4h::1
77a-bc98b345-4421-ba6d5-fc89f396e8855::ripple_osi.ehrscape.c4h::1
Ehrscape POST /composition

5. ‘Persistent’ Category
Each time new data is committed, the original instance
is overwritten
Problem list, End of Life Summary
77a-bc98b345-4421-ba6d5-fc89f396e8855::ripple_osi.ehrscape.c4h::1
77a-bc98b345-4421-ba6d5-fc89f396e8855::ripple_osi.ehrscape.c4h::2
Ehrscape PUT /composition

6. Episode vs Longitudinal persistence
Longitudinal Persistence
Some persistent summaries should exist and be updated throughout
the patient’s lifetime
End of Life summary, GP problem list
Episodic Persistence
Most outpatient and hospital summaries e.g Allergy lists, Problem
lists need to be re-created at admission, then maintained for the
period of admission.
A new Problem list may need ot be created for each episode of care

7. COMPOSITION ‘category’

8. but - always use ‘event’ !!!
We recommend always setting category
to ‘event’
Setting category to ‘persistent’ currently
removes the context of the Composition,
making it unsuitable for episodic care
i.e loses capacity to record start_time,
setting, location
will be changed soon in RM specification
Use documentation to tell developers
whether to save the composition as an
event, episodic persistent or longitudinal
persistent composition.

9. Developer documentation

10. Event vs. Persistent
Event compositions
Encounters - vital signs, outpatient
consultation
Reports - lab, radiology, MDT reports,
outpatient / discharge letters
Persistent compositions
Stateful summaries - End of life care
wishes
Curated lists
Problems/diagnoses, allergies, daily
history, procedures, immunisations

11. Contributions / versioning

12. Links
Most of the relationships between different Entries
and Elements is defined in archetypes and
templates, generally in the same Composition
Links allow the system developer to connect
different Entries which do not have a ‘pre-cooked’
association, and where the Entries live in different
Compositions

13. Links example