Geography and time-specific health data for environmental analysis

About the data source

Emergency department (ED) data used in the construction of this data set were sourced from the National Non-admitted Patient Emergency Department Care Database (NNAPEDCD). A data quality statement and detailed data specifications for the NNAPEDCD is available online at Hospitals – About the data and About our data – National hospitals data collection.

The data supplied by state and territory health authorities for the Non-admitted Patient Emergency Department Care (NAPEDC) National Minimum Data Set/National Best Endeavours Data Set (NMDS/NBEDS) were used by the AIHW to assemble the National Non-admitted Patient Emergency Department Care Database (NNAPEDCD). The data cover waiting times and other characteristics of presentations to public hospital emergency departments.

The NNAPEDCD provides information on the care provided for non-admitted patients registered for care in public hospital EDs that have:

• a purposely designed and equipped area with designated assessment, treatment, and resuscitation areas
• the ability to provide resuscitation, stabilisation, and initial management of all emergencies
• availability of medical staff in the hospital 24 hours a day
• designated ED nursing staff 24 hours per day 7 days per week, and a designated emergency nursing unit manager.

Methodology

In constructing this data set, emergency department presentations were grouped by week (based on date of presentation), geographical area (based on the patient’s place of usual residence), and principal diagnosis, for select groupings of interest. The derivation of these fields is described further below. 

The data set reports a count measure, which refers to the total number of presentations each week assigned a principal diagnosis falling within a given condition grouping, for a given geographical area. Counts represent the number of presentations rather than the number of people. 

The associated crude rate refers to the number of ED presentations per 100,000 population. Rates were calculated by dividing the count data by the estimate of population for the relevant week and geographical area derived as described in Population data.

Diagnosis groupings

The condition groups in Table 5 were selected for inclusion in the data set based on existing literature on the health impacts of bushfires and bushfire smoke pollution as well as subject matter expert advice. (Note that the ICD-10-AM Short List Eleventh Edition codes used to define the condition groupings in the emergency department context represent those Short List codes that fall into the ICD-10-AM version 11 condition grouping definitions used in the admitted patient analysis.)

Diagnosis data provided by jurisdictions to the NNAPEDCD have been reported using a variety of different coding schemas over the years and reporting varies by jurisdiction. Between 2014–15 to 2017–18, diagnosis data were reported using the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM), Second, Sixth, Seventh, Eighth and Ninth Editions (developed across time by the National Centre for Classification in Health (NCCH), the University of Wollongong (UOW), and the Australian Collaboration for Classification Development (ACCD)), the Systematized Nomenclature of Medicine – Clinical Terms – Australian version, Emergency Department Reference Set (SNOMED CT-AU EDRS), and the International Statistical Classification of Diseases and Related Health Problems, Ninth Revision, Clinical Modification (ICD-9-CM). Further detail on the prevalence of coding schemas used by different jurisdictions in different points in different years can be found in the appendices of data tables of Australian Hospital Statistics Emergency Department Care publications (see for example, Table C2 in Australian hospital statistics 2013–14: emergency department care, Table B1 in Emergency department care 2014–15: Australian hospital statistics and Table A2 in Emergency department care 2015–16: Australian hospital statistics).

From 2018–19, Principal diagnoses were provided to the NNAPEDCD using the ICD‑10‑AM Tenth Edition Principal Diagnosis Short List, developed by the Independent Health and Aged Care Pricing Authority (IHACPA) from the full version of ICD-10-AM. Between 2019–20 and 2021–22, the short list was based on ICD‑10‑AM, Eleventh Edition. The principal diagnosis data recorded in earlier coding schemas were all mapped to ICD‑10‑AM Principal Diagnosis Short List Eleventh Edition codes using mapping files.

A diagrammatic guide on the relationship between these items is shown in Figure 6.

Analysis by week

Presentations are grouped by week (Monday–Sunday) based on date of presentation. The weeks form a continuous time series over the temporal extent of the data set.

Analysis by geography

Analysis at the SA4 level was based on the patient’s usual area of residence (not the SA4 of the emergency department at which the patient presented). SA4 of usual residence was derived from SA2 of usual residence. Data in the NNAPEDCD were supplied by jurisdictions with SA2 of usual residence. From 2017–18 onwards, all jurisdictions supplied data by SA2 of usual residence according to the ASGS 2016 structure. For 2014–15 to 2016–17, while most jurisdictions supplied the data with SA2 of usual residence according to the ASGS 2011 structure, NSW and one hospital in Victoria provided the data with SLA of usual residence. SA2 ASGS 2011 of usual residence was derived by the AIHW through mapping on a probabilistic basis in these cases. For the current project we mapped records with SA2 of usual residence in the ASGS 2011 structure to the ASGS 2016 structure using a concordance file and the SA4 of usual residence derived from the SA2 ASGS.

Reporting of results

In line with AIHW policy on reporting to manage confidentiality, as well as data management protocols for this data set, some data have been suppressed. In particular, where counts for a diagnosis group on a given week in a given jurisdiction or SA4 were less than 5, both the counts and rates were suppressed. Secondary suppression was also applied throughout in the event that a suppressed cell could be identified from a higher-level aggregation.

Data considerations and limitations

Divergence from reporting data

The data presented here on emergency department presentations differ from data presented elsewhere (for example, used for reporting purposes) for multiple reasons. Of particular note, these data are geolocated according to the patient’s usual place of residence, rather than the emergency department location.

Annual structure of source data

The NNAPEDCD is a compilation of annual data sets, each comprising emergency department presentations within a particular financial year. Changes to coding standards and practices often occur at the juncture of these financial years. 

Specifications of geolocation

The geolocation of the data is based on patients’ usual residence, and not the location of the emergency department. The patient’s place of usual residence may differ from the location of the patient at the time of condition onset, and any exposure to an environmental influence. 

Geographical scope

Because the scope of the collection is limited to emergency departments that meet nationally agreed criteria, most of the data provided to the NNAPEDCD relate to emergency department care provided to people living in Major cities. The NNAPEDCD may not include emergency presentations to hospitals that have emergency departments that are not in scope for the Non-admitted Patient Emergency Department Care (NAPEDC) National Minimum Data Set (NMDS)/National Best Endeavours Data Set (NBEDS).

Quality of geolocation data

All the data in this release are presented according to a common geographical structure – 2016 ASGS SA4. However, prior to 2017-18, the 2011 ASGS SA4 structure was used to record patients’ area of residence in the underlying source data (NSW data were actually reported to the AIHW using the ASGC SLA structure, and these data were mapped to 2011 SA2s in the compilation of the NNAPEDCD). A probabilistic population-weighted mapping file has been applied to map these regions to the ASGS 2016 structure in the construction of this data set. For a description of this process, see Analysis by geography. 

This mapping will tend to reduce the quality of historical geolocation data reported by 2016 ASGS SA4 (relative to the recent period during which the 2016 ASGS structure was reported in the source data), and the issue will affect some geographical areas more than others. Where whole 2011 ASGS SA2s are mapped to a single 2016 ASGS SA4, the mapping process does not introduce any error. However, some error is introduced when areas are split across 2016 SA4s during the mapping process. 

Variation in classifications, coding standards and practices

Although there are national standards for data on non-admitted patient emergency department services, the way those services are defined and counted varies across states and territories, and over time. Therefore, comparisons of ED presentations across jurisdictions, and across time should be considered with caution, and made with reference to the accompanying notes in data tables or in this report.

For more detailed information on the source data, see About the data - Hospitals info.

Quality and comparability of diagnosis data

Practices and policies around recording diagnoses have varied significantly over time, and across jurisdictions. In the emergency department setting, prior to 2018-19 a number of different coding schemas were used to record patients’ principal diagnoses across different jurisdictions at different times (see for example, Table C2 in Australian hospital statistics 2013–14: emergency department care, Table B1 in Emergency department care 2014–15: Australian hospital statistics and Table A2 in Emergency department care 2015–16: Australian hospital statistics). 

Care has been taken in aligning the data to some extent for this data release; see the Diagnosis groupings section for detail on the mapping process. However, the changes in classifications and practices used to code presentation diagnoses may still affect the comparability of the presentations and diagnosis data in the data set over time and across jurisdictions. 

A more general consideration with data from emergency departments is that diagnoses are not coded by qualified clinical coders, as they are for admitted patient care. Emergency department diagnoses data are coded at point of care by medical, nursing or clerical personnel.

State-specific data supply changes

Prior to 2020–21, the following jurisdictions provided data to the NNAPEDCD using the NAPEDC NBEDS specification:

• Queensland (from 2015–16 to 2019–20).
• Victoria and Western Australia (from 2016–17 to 2019–20).

All other states and territories used the NAPEDC NMDS. The data provided using the NAPEDC NBEDS may not be entirely comparable with data provided using the NAPEDC NMDS. For example, under the NAPEDC NBEDS specification, patients in transit are included as Emergency presentations.

From 2020–21, the NNAPEDCD may not include emergency presentations to hospitals that have emergency departments that are not in scope for the NAPEDC NMDS.

In New South Wales: 

• In 2018–19 Northern Beaches Hospital opened, Manly Hospital closed, and Mona Vale hospital ceased providing emergency department services. Byron Central Hospital commenced providing emergency department care in 2015–16, replacing care previously provided by Mullumbimby Hospital and Byron Bay Hospital.

In Queensland:

• The Sunshine Coast University Hospital opened in March 2017, but this did not constitute a change in coverage, as the emergency department services were previously provided by a number of smaller hospitals in the region, which reported data for the NNAPEDCD.
• Data for the Royal Children’s Hospital and the Mater Children’s Hospital were included in reporting in 2014–15. During 2014–15, they were replaced by the Lady Cilento Children’s Hospital. All 3 hospitals reported emergency department care data in 2014–15.

In Western Australia:

• Fiona Stanley Hospital Launched its Ambulatory Emergency Care Clinic in February 2021, which numerous Urgent and Semi-urgent presentations were referred to from triage for treatment.
• In 2018-19, six Public acute group C hospitals started reporting in Western Australia. This constitutes a change in coverage, as the analogous activity was previously not reported for the NNAPEDCD.
• Nickol Bay Hospital closed and was replaced by Karratha Health campus during the 2018–19 year. Both hospitals were reported in 2018–19.
• Perth’s Children’s Hospital opened in June 2018 and Princess Margaret Hospital closed. Both hospitals were reported in 2017–18.
• The St John of God Midland Public Hospital opened, and the Swan District Hospital closed in November 2015. Both hospitals were reported in 2015–16.
• In 2014–15, Busselton Health Campus began reporting emergency department care data, after the Busselton hospital was redeveloped to include a larger emergency department. This constituted a change in coverage as the activity was previously not reported for the NNAPEDCD.
• In 2014–15, the Fremantle Hospital’s emergency department was replaced by the Fiona Stanley Hospital emergency department. Both hospitals were reported for 2014–15.

In South Australia:

• South Australia commenced reporting for three Public acute group C hospitals in 2019–20: Mount Barker District Soldier Memorial Hospital, South Coast District Hospital and Murray Bridge Soldier’' Memorial Hospital. This constitutes a change in coverage.

In the Northern territory:

• Palmerston Regional Hospital opened in August 2018. This constitutes a change in coverage.