Assigning demographic variables and region of residence

Age and sex

The cohort included people aged 30 and over. Younger people were out of scope for this study because the number of people aged under 30 living with dementia (including childhood dementias) would be too small to analyse by smaller geographies, and people are likely to use different services.

Age at the first service event in 2019 was calculated from the "age at event zero" variable in the NIHSI patient demography file (95% of the cohort had a service event in January 2019).

Sex was derived in the following order of priority: from the NIHSI patient demography file, or the last service event in 2019, or the latest service event in the NIHSI.

Geographical region of residence

This report presents information on people living with dementia based on where they lived, not where they received services. People are likely to have used services outside of their region of residence.

To ensure comparability across regions, data were only analysed for people living in states/territories with hospital data in the NIHSI 2020–21: NSW, Victoria, Queensland, South Australia, Tasmania and the ACT. Similarly, people who only had a dementia record in a private hospital service were excluded because private hospital data were not consistently available for all states/territories.

The smallest geography in the NIHSI is Statistical Area level 2 (SA2) (ABS 2016). Region of residence was based on a person’s latest recorded SA2 region or postcode in the NIHSI, either in the analysis year of 2019 or, if they had died, their death record in January 2020–December 2021.

People living with dementia may need to change their residence to be nearer to family and carers, or to receive health and/or aged care services. The SA2 regions and postcodes of residential aged care facilities were not available in the NIHSI, so residence was taken from other sources. It is known that people often do not update their address in the Medicare system (used for PBS and MBS data), so these sources were considered less accurate than deaths or hospitals data.

When a person had records in more than one dataset, the latest recorded SA2 region or postcode was taken using the following order of priority:

  • National Death Index (for those in the cohort that died between January 2020 and December 2021)
  • Hospital data (NHMD and NNAPEDC) (2019)
  • Pharmaceutical Benefits Scheme (2019)
  • Medicare Benefits Schedule (2019)
  • Postcodes were only used if there was no record of SA2 region. Postcodes were allocated to the SA2 region where the largest percentage of the population lived.

Data are presented at four levels of geography: