The age of each person in this analysis was calculated based on age at event (when the person died or when service/prescription was provided). Information on month and year of birth was used to first estimate single year ages of each person in the study groups, and then derived their broad age groups for reporting purposes.
Using this approach, in some instances a person’s calculated age may be older than the actual age they were at time of the event. For instance, a person whose date of birth was 1/04/2005 and who used a service on 1/03/2015 will be in the 10-year age group 10–19 despite only being 9 at the time of event. It is the age the person is turning in the year of the event that is used.
For census outcomes the variable for age in 10–year age groups, which is already derived in the provided data, was used for reporting by age groups.
Country of birth
The country of birth variable in the Settlement Database (SDB) is a 3-letter character variable that is not standardised and therefore country of birth had to be sourced from other data sets. For deaths and Census there are county of birth variables in the data sets which were used. There is no country of birth variable in the Medicare Consumer Directory (MCD) where the other demographics variables for the Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme (PBS) analysis were taken. The country of birth variable for the MBS and PBS analysis was taken from the Person-Level Integrated Data Asset (PLIDA) combined demographics file. This file combines the demographic information from various core data sources. The country of birth variables from the Social Security and Related Information (DOMINO) Centrelink administrative data (2006–2020), Census 2011/2016 and deaths (2007–2018) are examined and the most frequently reported country of birth for each spine id is recorded as the country of birth on the combined demographics file.