Injuries in children and adolescents 2021–22

A diagnosis of injury is defined as ICD-10-AM codes in the range S00–T75 or T79, using ‘Chapter 19 Injury, poisoning and certain other consequences of external causes’. A primary diagnosis of injury is when one of the specified codes is the first diagnosis code reported, while an additional diagnosis of injury is when one of the specified codes is reported but not as the first diagnosis.

A person may have more than one incident of injury resulting in hospitalisation in a financial year and each case of hospitalisation will be counted separately in this report. This is because we are counting incidents of injury resulting in hospitalisation, rather than the number of people who were hospitalised, in a given financial year. If a single incident led to an admission in more than one hospital, the incident has only been counted once. Therefore, counts of injury cases will be lower than the count of hospital records indicating injuries.

Inclusion criteria

• Records with the maximal snapshot id in any database where the date of separation falls within the timeframe defined in the report. 
• NHMD or NNAPEDCD records with a principal diagnosis in the ICD 10 AM range S00–T75 or T79, using ‘Chapter 19 Injury, poisoning and certain other consequences of external causes’.
• NHMD records with a separation date between 1 July 2012 to 30 June 2022.
• NNAPEDCD records with a presentation date between 1 July 2021 to 30 June 2022.
• Patient age specified between 0–18 years inclusive for ‘children’, and specified age greater than or equal to 19 for ‘adults’.

Exclusion criteria

• Records were excluded where the AIHW ‘standard analysis’ flag was absent, that is, care type was newborn with unqualified days only (7.3), organ procurement – posthumous (9), or hospital boarder (10).
• 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) are excluded. 

Estimating index cases, not counting separations

Each record in the NHMD refers to a single episode of care in a hospital. Some injury incidents result in more than one episode of care and, therefore, more than one record. 

To minimise the impact of overcounting where a person experienced multiple episodes of care relating to the same condition, the following criteria are applied to estimate incidents:

•    Excludes records where admission mode is transfer from another hospital (1)

•    Excludes records where admission mode is statistical admission (2) and care type is not acute (1, 7.1, 7.2)

•    Excluding records where care involving use of rehabilitation procedures (Z50) appears as an additional diagnosis and care type is not acute (1, 7.1, 7.2).

Diagnosis, intervention, and external cause data in the NHMD for 2021–22 was reported to using classifications from the 11th edition of the International statistical classification of diseases and related health problems, 10th revision, Australian modification (ICD-10-AM) (ACCD 2019a).

In tables and figures, information on diagnoses, external causes, and interventions are presented using the codes and abbreviated descriptions of the ICD-10-AM and the 11th edition of the Australian classification of health interventions (ACHI). Full descriptions of the categories are available in ICD-10-AM/ACHI publications (ACCD 2019a, ACCD 2019b, ACCD 2019c).

Where data are presented in a time series incorporating previous reporting periods, these have been coded according to the following editions of ICD‑10‑AM:

• 7th edition for 2011–12 and 2012–13 hospital data
• 8th edition for 2013–14 and 2014–15 hospital data
• 9th edition for 2015–16 and 2016–17 hospital data
• 10th edition for 2017–18 and 2018–19 hospital data
• 11th edition for 2019–20, 2020-21 and 2021–22 hospital data.

The NHMD is structured so that the first listed external cause for a record relates to the first listed injury diagnosis (principal diagnosis). While multiple external causes may be recorded for a separation, we report only one cause for each injury, referred to as ‘nominal external cause’ in these notes. The following steps are followed to determine the nominal external cause for each injury hospitalisation:

1. The first reported external cause is taken to be the nominal external cause
2. If the nominal external cause, as determined by step 1, is U92.0 (Staphylococcus aureus) or a supplementary factor (Y90–Y98), then the second reported code is taken to be the nominal external cause
3. If the nominal external cause, after steps 1 and 2, relates to complications of medical and surgical care (Y40–Y84), sequelae of external causes of morbidity and mortality (Y85–Y89), or a supplementary factor code (Y90–Y98), then the record is excluded.

The categorisation of external causes using ICD-10-AM codes are detailed in Appendix tables to technical notes for Injury in Australia. 

Due to differences in state/territory data collection, no nationally comparable external cause data is available for NNAPEDCD records. 

To categorise injuries by type and body part injured, Injury in Australia’s principal diagnosis matrix has been applied (as outlined in the Appendix tables to technical notes for Injury in Australia). Body part 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 hospitalised injury cases because some injuries are not described in terms of body region.

Common demographic categories are defined in Table 1.