Head injuries in Australia 2020–21

The aim of this section of the report is to count the number of head injury emergency department presentations in Australian public hospitals from 1 July 2020 to 30 June 2021, inclusive. In all cases included in this report, patients had a head injury diagnosis code in their record.

Emergency department presentations for injury incidents are generally more numerous than the number of hospitalisations. This is because many injuries can be treated in emergency departments and do not require admission to a hospital. Many more people with injuries are treated outside of a hospital such as at a general practice – these injuries are not captured in ED data. A small number of severe injuries result in the person being dead on arrival at the emergency department, these cases are counted in both the emergency department and deaths data sources. Cases that are hospitalised after presenting to emergency departments are counted in both ED and hospitals data sources.

Head injury emergency department presentations account for 21% of all emergency department injury presentations. This document covers:

• Definitions and classifications used
• Presentation of data in this report
• Analysis methods.

Non-Admitted Patient Emergency Department Care Data

The data supplied by state and territory health authorities for the Non-admitted Patient Emergency Department Care (NAPEDC) National Minimum Data Set (NMDS) 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. 

From 2020–21, all jurisdictions provided data for the NNAPEDCD using the NAPEDC NMDS. The NNAPEDCD provides information on the care provided (including waiting times for care) for non-admitted patients registered for care in public hospital emergency departments that have:

• 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 emergency department nursing staff 24 hours per day 7 days per week, and a designated emergency department nursing unit manager.

Emergency departments (including ‘accident and emergency’ or ‘urgent care centres’) that do not meet the criteria above are not in scope for the NMDS, but data may have been provided for some of these by some states and territories.

Patients who were dead on arrival are in scope if an emergency department clinician certified the death of the patient. Patients who leave the emergency department after being registered/triaged to receive care and then advised of alternative treatment options are also in scope. 

The scope includes only physical presentations to emergency departments. Advice provided by telephone or video conferencing is not in scope, although it is recognised that advice received by telehealth may form part of the care provided to patients physically receiving care in the emergency department. Also excluded from the scope of the NMDS is care provided to patients in general practitioner co-located units. 

Since 2003–04, data for the NNAPEDCD have been reported annually. The most recent reference period for this data set includes records for Non-admitted patient emergency department service episodes between 1 July 2020 and 30 June 2021. 

This report is the first use of NNAPEDCD for AIHW national injury surveillance. Future injury reports may use slightly different procedures of extracting and analysing data from this source, and care should be considered when making direct comparisons to this report. 

Missing or invalid data

In some cases, the data provided may include missing values (for example, the date/time of physical departure was not recorded), or invalid values (for example, if the time of physical departure was recorded as occurring before the time of presentation).

External cause data

The NNAPEDCD does not include a field for external cause of injury (such as a fall or transport accident) or other related data such as place of occurrence, mechanism of the injury, activity being undertaken at the time, intent and perpetrator. Australian injury surveillance systems have a major focus on the external causes of injuries, which is especially important from a prevention perspective. The absence of these national data obstructs direct comparisons between the causes of injury across hospitalisations, deaths, and ED presentation data.

Reporting diagnosis information

For the 2020–21 NAPEDC NMDS/NBEDS, diagnosis information was reported using the ED ICD-10-AM version 11 shortlist that can be found on the website of the Independent Hospital Pricing Authority.

Episode end status

There is a difference between the number of presentations with a type of visit of Dead on arrival and the number of presentations with an episode end status of Dead on arrival. All presentations with a type of visit of Dead on arrival had an episode end status of Dead on arrival. However, some presentations with an episode end status of Dead on arrival did not have a type of visit of Dead on arrival. 

Estimated resident populations

All populations are based on the estimated resident population (ERP) population as at 30 June immediately prior to the reporting period (that is, for the reporting period 2020–21, the population at 30 June 2020 is used). The population is used as the denominator for age‑specific and age‑standardised rates.

The ERP as at 30 June 2001 is used as the standardising population throughout the report (ABS 2003).

The COVID-19 pandemic and resulting Australian Government closure of the international border from 20 March 2020 disrupted the usual Australian population trends. The ERP for 30 June 2020, used in this report, reflects this disruption.

All population data are sourced from the Australian Bureau of Statistics (ABS) as follows:

• General populations are from National, state and territory population
• Remoteness populations (available on request from ABS)
• Socio-Economic Indexes For Areas (SEIFA) Index of Relative Socio-Economic Disadvantage (IRSD) quintile populations are from AIHW analysis of Census of Population and Housing: Socio-Economic Indexes for Areas (ABS 2018) and Regional population.

This report estimates the number of incidents of head injuries that lead to an emergency department presentation. This represents 21% of injury-related emergency department presentations in the NAPEDC.

Selection criteria

The following criteria were used to estimate numbers of cases of head injury emergency department presentations in Australia.

1. Financial year of presentation, records dated from 1 July 2020 to 30 June 2021 inclusive
2. Head injury principal diagnosis in the ICD-10-AM range S00–S09, T00.0, T01.0, T02.0, T03.0, T04.0, T06.0, T15, T16, T20, T26, T33.0, T34.0, T35.2 (Table 1) using ‘Chapter 19 Injury, poisoning and certain other consequences of external causes’.

Some analysis compared emergency department presentations for head injuries with all injuries. Alongside the scope above for head injuries, all injuries were identified through the following criteria:

1. Financial year of presentation, from 1 July 2020 to 30 June 2021
2. Principal diagnosis in the ICD-10-AM range S00–T75 or T79 using ‘Chapter 19 Injury, poisoning and certain other consequences of external causes’.

This scope excludes injuries due to Complications of surgical and medical care (T80 – T88) and Sequelae of injuries, of poisoning and of other consequences of external causes (T90 – T98) in line with our reporting on injury hospitalisations.

While up to two additional diagnoses can be reported within the data collection, very few records within the NAPEDC contain additional diagnoses. 6.8% of observations in the 2020-21 NAPEDC database had a first additional diagnosis, while just 0.6% contained a second additional diagnosis. Consequently, only presentations with a relevant principal diagnosis were considered within the selection criteria.

The totals in tables include data only for those states and territories for which data were available, as indicated in the tables. Throughout the report, percentages may not add up to 100.0 because of rounding. Percentages and rates shown as 0.0 or 0 indicate a zero. 

Head location and injury type are derived from the principal diagnosis of the case. The sum of injuries by body part may not equal the total number of injury emergency department presentations because some injuries are not described in terms of body region.

The patient’s age is calculated at the date of admission. In tables by age group and sex, presentations for which age and/or sex were not reported are included in the totals.

Suppression of data

The AIHW operates under a strict privacy policy based on Section 29 of the Australian Institute of Health and Welfare Act 1987 (AIHW Act). Section 29 requires that confidentiality of data relating to persons (living and deceased) and organisations be maintained. The Privacy Act 1988 (Privacy Act) governs confidentiality of information about living individuals.

The AIHW is committed to reporting that maximises the value of information released for users while being statistically reliable and meeting legislative requirements described in the AIHW Act and the Privacy Act.

Data (cells) in tables may be suppressed to maintain the privacy or confidentiality of a person or organisation; or because a proportion, rate (numerator or denominator) or other measure is related to a small number of events (and may therefore not be reliable). Data may also be suppressed to avoid attribute disclosure. The abbreviation ‘n.p.’ (not published) has been used in tables to denote these suppressions. In these tables, the suppressed information is included in the totals.

Principal diagnosis reporting

From 2018–19, Principal diagnoses were provided using the ICD-10-AM Principal Diagnosis Short List, developed by the Independent Hospital Pricing Authority (IHPA) from the full version of ICD-10-AM. 

For 2020–21, the short list was based on ICD-10-AM version 11.

The codes included in scope for head injury ED presentations were the same as those used for admitted patients. Since some jurisdictions code the principal diagnosis from the ICD-10-AM version 11 rather than the Principal Diagnosis Short List, these codes were included for completeness. In 2020–21, there were 21 head injury presentations for codes not on the Principal Diagnosis Short List. 

Waiting time to commencement of clinical care

The waiting times are determined as the time elapsed between presentation to the emergency department and the commencement of clinical care. The calculation is restricted to presentations with a type of visit of Emergency presentation, and presentations were excluded if the waiting time was missing or invalid, or if the patient Did not wait to be attended by a health care professional, was Dead on arrival or Registered, advised of another health service and left without being attended to. See Appendix A for information on the completeness of the data provided for waiting times calculations.

Proportion of presentations seen on time

The proportion of presentations seen on time was determined as the proportion of presentations in each triage category with a waiting time less than or equal to the maximum waiting time stated in the Australasian Triage Scale definition. Triage categories and respective clinically appropriate waiting times are as follows (for further details see AIHW METEOR):

For this report, a patient with a triage category of Resuscitation was considered to be seen on time if the waiting time to commencement of clinical care was less than or equal to 2 minutes. 

Quality of data on ED waiting times

For 2020–21, about 870 head injury cases that should have been included in the calculation of waiting times statistics were excluded, as they did not have a valid commencement of clinical care time recorded.

The criteria used to determine the proportion of Resuscitation patients seen on time varies between jurisdictions, therefore, the proportions of Resuscitation patients seen on time presented in this report may differ from those reported by individual jurisdictions.

Proportion of presentations ending in admission

The proportion of presentations ending in admission is determined as the proportion of all emergency presentations with an episode end status of Admitted to this hospital (either short-stay unit, hospital-in-the-home, or non-emergency department hospital ward).

Admission to hospital from emergency departments

Admission to hospital from emergency departments (for patients who were subsequently admitted) is calculated using the emergency department length of stay for presentations with an episode end status of Admitted to this hospital (either short-stay unit, hospital-in-the-home, or non-emergency department hospital ward).

Age and sex of patient

All states and territories supplied the date of birth of the patient, from which the age of the patient at the date of presentation was calculated. For 32 records, the age of the patient could not be calculated, as date of birth was missing. For 46 records, the sex of the patient was reported as either Intersex or indeterminate or Not stated/inadequately described.

If not otherwise indicated, data elements were defined according to their definitions in the AIHW’s Metadata Online Registry (METEOR), and summarised in the Glossary.

In particular, data element definitions for the Non-admitted patient emergency department care National Minimum Data Set (NMDS) are available online at: METEOR website.

Table 1 describes the inclusion for each major principal diagnosis category and the relevant ICD-10-AM codes.