Technical notes


This report counts and describes injury cases that result in hospital admission, presentation to the emergency department, and/or death.

Our counting method is different to some other AIHW reporting (such as MyHospitals), where each use of a service may be counted rather than each incident. A single incident can lead to more than one use of a service. Our exclusion method minimises the associated double counting but does not eliminate it.

If a person dies from an injury after being admitted to hospital, both the hospitalisation and the death were counted for this report.

Injury hospitalisations

The terms ‘injury hospitalisation’, ‘hospitalised injury’ and ‘hospitalised case’ in this report refer to incidents where a person was admitted to hospital with injury as the main reason, an injury case. If a single incident led to an admission in more than one hospital, the incident has only been counted once.


To minimise double-counting of hospitalisations for injuries, we have excluded admissions that are transfers from another hospital and admissions with rehabilitation procedures (except for acute hospital admissions).

Injuries caused by complications of surgery or other medical care, or injuries that are a subsequent condition caused by a previous injury, are not included in this report.

Date of admission versus separation

The seasonal differences figures and tables in this report were based on date of admission data, to approximate the dates of the injuries leading to hospitalisations. All other annual totals were based on year of separation. Separation does not necessarily occur in the same month (or year) as admission. Partly because of this, summing the counts in the seasonal differences tables would produce slightly different numbers than the annual totals. Also, the admission counts were adjusted to suit comparison between months of different length.

Injury emergency department presentations

Emergency department (ED) care is a form of non-admitted hospital care and is different to a hospitalisation which involves an admission to hospital. While emergency department presentation records have many of the same fields as hospital records, there are key differences in the way they are structured.

A notable difference in ED records compared with hospitalisations and deaths, is the lack of external cause data. External cause and related data on the injury include details such as place of occurrence, mechanism of the injury, activity being undertaken at the time, intent and perpetrator. Additionally, there are unique variables only found within ED records such as triage category and waiting time that cannot be compared against hospitalisations and deaths.

Injury deaths

Death records have many of the same fields as hospital records and emergency department presentations, however there are differences in the way they are structured.

It is not always possible to determine the main cause of death when multiple causes are involved. For this reason, a different selection criterion must be applied to reasonably identify where injuries played a role. As a result, each death where injury played a role has been counted once in the total for this report, but in some cases counted in more than one injury cause category.

To understand the analysis in more detail, please find below:

  • Head injury hospitalisations in Australia, 2020–21: about the data
  • Head injury emergency department presentations in Australia, 2020–21: about the data
  • Head injury deaths in Australia, 2020–21: about the data
  • Appendix tables specifying the ICD-10 codes used for each cause category