11 April 2025
Chris Johnston
[FYI request #28619 email]
Tēnā koe Chris
Your request for official information, reference: HNZ00083198
Thank you for your email on 24 March 2025, asking Health New Zealand | Te Whatu Ora for the
following under the Of icial Information Act 1982 (the Act):
“SNOWMED (and READ) codes have a clear hierarchical structure, therefore the
aggregation of these is "collation" as defined by the Ombudsman, does not require
substantial skil or research, and are not the creation of information as HealthNZ attempts
to claim.
Further, for the original OIA this OIA was asking for further information on, you state that
the SNOMED data WAS aggregated already. That is any "medical" judgement has already
been undertaken for this OIA request and its predecessor. That OIA was answered - which
set the benchmark for acceptability of this request on the SNOMED data alone.
The joining of tables to dose does not require substantial skil and research to a degree that
would exclude this data analyst activity from being covered under the Official Information
Act because this type of join has been done before for other OIAs including myself. Linking
tables in this way is a core data analyst skil , and HealthNZ confirms that these people exist
in your organisation and have the skil . I can write the code myself - it is not hard - and I am
not a developer.
Can you confirm that HealthNZ have not listed all systems in which this data is contained in
the response to the previous OIA, and list any excluded systems? That is, is all the
required data for this OIA also stored in HealthNZ's data warehouse environment. I believe
that this is on the Snowflake platform, but other instances where the required data is
already available for collation within the same environment may exist.
A reminder that the completeness of the data or the coding consistency across hospitals at
the time is not the issue at stake. The OIA allows the data to be requested "as is" from the
databases - in a collated form.
Please confirm to the Ombudsman and myself that the above is accurate, and state if you
wil be delivering the data requested by the OIA request ASAP. I wil be updating the
Ombudsman that HealthNZ stil appears to be in a defensive posture - which is of course
disappointing.
Response
With regards to your questions about Emergency Department information, some public hospital
emergency departments in New Zealand first began providing SNOMED codes for Chief
Presenting Complaint and Diagnosis from July 2019. Not all hospitals began reporting at the same
time. Al publicly funded hospitals attached to a former District Health Board were reporting
SNOMED coding for Chief Presenting Complaint from their Emergency Departments by August
2023. However, other charitable and non-profit health facilities with Accident and Medical Centres
are not yet reporting SNOMED coded data.
This means that prior to August 2023, the data you have requested is not complete enough to
report on at a national level. Health NZ staf working in the areas of data quality and standards
continue to work together with reporting hospitals to ensure the quality and completeness of this
data.
SNOMED is a hierarchical coding system that has around 125,000 codes for clinical findings and
disorders. There is an explicit SNOMED code for chest pain, and a further 121 codes that
represent types of chest pain – for example, ‘chest pain due to pericarditis’.
To simplify the coding of emergency department visits, a subset of about 150 codes is used for
recording Chief Presenting Complaint, and a subset of about 1500 codes is used for recording
diagnosis. For each emergency department visit, exactly one chief presenting complaint and
between one and six diagnosis codes are recorded by clinicians.
The emergency department presenting complaint subset has just one chest pain code, while the
emergency department diagnosis subset has four codes. These codes can be used to select all
emergency department visits where chest pain or one of its subtypes has been explicitly recorded,
but these may not capture the events you are interested in. For example, the chest pain related
codes do not include myocardial infarction. Health NZ are undertaking work internally which wil
allow us to go beyond hierarchies to undertake more complex queries, such as responding to your
request. This work is not yet complete.
We therefore ask that you review the more than 1500 possible codes related to the concept of
chest pain, and advise which codes are of interest to you. We can then provide the number of
events with these codes. We cannot provide this data over time for all ED services in New
Zealand, but we can provide the data we hold. Please find these lists as Appendices 1 and 2.
How to get in touch
If you have any questions, you can contact us at
[email address].
If you are not happy with this response, you have the right to make a complaint to the
Ombudsman. Information about how to do this is available at
www.ombudsman.parliament.nz or
by phoning 0800 802 602.
As this information may be of interest to other members of the public, Health NZ may proactively
release a copy of this response on our website. Al requester data, including your name and
contact details, wil be removed prior to release.
Nāku iti noa, nā
Stuart Bloomfield
Interim Director Data and Analytics
Planning, Funding and Outcomes
TeWhatuOra.govt.nz
Health NZ, PO Box 793,
Wel ington 6140, New Zealand
