What is ERA?

Aboriginal people are known to be under-reported on population-based health and health-related data collections in NSW. Enhanced Reporting of Aboriginality (ERA) is a method that improves reporting on the health of Aboriginal people from administrative data collections using record linkage. Enhanced reporting relies on having linked records from the same person collected from independent sources, such as hospital admissions, emergency department presentations, births and deaths. Each record in the chain of linked records contributes to the weight of evidence as to whether a person is truly Aboriginal, but may have been recorded as being non-Aboriginal or 'unknown' on some records.

How is the level of reporting calculated?

The recording of Aboriginality on each original record represents the 'observed' number. The 'expected' number represents the number of records likely to be for an Aboriginal person based on the ERA process. The level of reporting of Aboriginal people in each data collection is then calculated by comparing the observed counts of records reported for Aboriginal people with the expected counts of records based on the ERA variable and presenting the result as a percentage.

The following approach was used to assess each health record from each source as a 'unit of information' to compute the ERA variable:

1. If the person has 3 or more units of information, at least 2 units indicating that the person is Aboriginal are required to report the person as Aboriginal; or
2. If the person has 1 or 2 units of information, 1 is sufficient to report the person as Aboriginal. This approach results in the creation of an ERA variable, which indicates whether the person is reported as Aboriginal based on the above weight of evidence.
3. If a person is listed as Aboriginal on their death certificate they are always reported as Aboriginal, regardless of the weight of other information.

For the NSW Admitted Patient Data Collection and NSW Emergency Department Data Collection, linked records of the following datasets were used to create the ERA variable:

• NSW Admitted Patient Data Collection
• NSW Emergency Department Data Collection
• Australian Coordinating Registry Cause of Death Unit Record File
• NSW Perinatal Data Collection
• NSW Registry of Births, Deaths and Marriages birth registration records.

For the NSW Perinatal Data Collection, linked records of the following datasets were used to create the ERA variable:

• NSW Admitted Patient Data Collection
• NSW Emergency Department Data Collection
• Australian Coordinating Registry Cause of Death Unit Record File
• NSW Perinatal Data Collection
• NSW Registry of Births, Deaths and Marriages birth registration records
• NSW Notifiable Conditions Information Management System.

Record linkage was carried out by the Centre for Health Record Linkage (CHeReL) (www.cherel.org.au).

References

Australian Institute of Health and Welfare. Indigenous identification in hospital separations data–Quality report. Cat. no. IHW 90. Canberra: AIHW, 2013. Available at http://www.aihw.gov.au/publication-detail/?id=60129543215 

Bentley JP, Taylor LK, Brandt PG. Reporting of Aboriginal and Torres Strait Islander peoples on the NSW Admitted Patient Data Collection: the 2010 Data Quality Survey. NSW Public Health Bull 2012; 23(2): 17–20. Available at http://www.publish.csiro.au/paper/NB11034.htm

Nelson, M.A., Lim, K., Boyd, J. et al. Accuracy of reporting of Aboriginality on administrative health data collections using linked data in NSW, Australia. BMC Med Res Methodol 20, 267 (2020).Available at https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/s12874-020-01152-2

Population and Public Health Division. Improved reporting of Aboriginal and Torres Strait Islander peoples on population datasets in New South Wales using record linkage–a feasibility study. Sydney: NSW Ministry of Health, 2012. Available at https://www.health.nsw.gov.au/hsnsw/Publications/atsi-data-linkage-report.pdf