• AIHW Data Quality Statements, Superseded 08/07/2022

Summary of Key Issues

• BreastScreen Australia data are highly relevant and timely for monitoring trends in breast screening participation and the detection of invasive breast cancer and ductal carcinoma in situ (DCIS) through BreastScreen Australia.
• A relatively small amount of screening mammography occurs through services other than BreastScreen Australia.
• Indigenous status and whether a main language other than English is spoken at home are self-reported at the time of screening.

Description

BreastScreen Australia is Australia’s national, population-based breast cancer screening program that aims to reduce illness and death from breast cancer through an organised approach to the early detection of breast cancer, using screening mammography to detect unsuspected breast cancer in women every 2 years, with data reported on those aged 50–74.

BreastScreen Australia is a joint program of the Australian and state and territory governments, with BreastScreen registers in each state and territory recording data collected during a woman’s contact with a BreastScreen service.

Data from each BreastScreen program register are supplied annually to the AIHW. These data are compiled into the BreastScreen Australia database, held at the AIHW to enable national monitoring of BreastScreen Australia and are reported in the annual BreastScreen Australia monitoring report.

Some BreastScreen data are supplied as aggregate data and therefore cannot be interrogated in more detail.

The majority of screening mammography performed in Australia is through BreastScreen Australia. However, a relatively small amount of screening mammography occurs through services other than BreastScreen Australia, which are not within the scope of these data.

The Australian Institute of Health and Welfare (AIHW) is a major national agency set up by the Australian Government under the Australian Institute of Health and Welfare Act 1987 to provide reliable, regular and relevant information and statistics on Australia's health and welfare. It is an independent Commonwealth entity established in 1987, governed by a management Board, and accountable to the Australian Parliament through the Health Portfolio.

The AIHW aims to improve the health and wellbeing of Australians through better health and welfare information and statistics. It collects and reports information on a wide range of topics and issues, ranging from health and welfare expenditure, hospitals, disease and injury, and mental health, to ageing, homelessness, disability and child protection.

The Institute also plays a role in developing and maintaining national metadata standards. This work contributes to improving the quality and consistency of national health and welfare statistics. The Institute works closely with governments and non-government organisations to achieve greater adherence to these standards in administrative data collections to promote national consistency and comparability of data and reporting.

One of the main functions of the AIHW is to work with the states and territories to improve the quality of administrative data and, where possible, to compile national datasets based on data from each jurisdiction, to analyse these datasets and disseminate information and statistics.

The Australian Institute of Health and Welfare Act 1987, in conjunction with compliance to the Privacy Act 1988, ensures that the data collections managed by the AIHW are kept securely and under the strictest conditions with respect to privacy and confidentiality.

For further information see the AIHW website www.aihw.gov.au.

BreastScreen data are collected by and held in the BreastScreen register within each state and territory, and are managed by state and territory BreastScreen programs.

The AIHW has been receiving BreastScreen data from state and territory BreastScreen programs since 1996.

BreastScreen data are generally available within 6–12 months (it can take up to 12 months for final pathology results on all breast tissue samples to be received by BreastScreen registers). The BreastScreen Australia database cannot be fully compiled until the final jurisdiction supplies its data.

Participation data for the previous calendar year are supplied in July each year. Recall to assessment, invasive breast cancer detection and DCIS detection data for the previous calendar year are supplied July–December each year. Rescreening and sensitivity data lag behind, as the specifications for these require at least 2 years to pass before they can be calculated.

The current BreastScreen Australia database contains data on women who participated in BreastScreen Australia in 2019 and 2020.

BreastScreen Australia data are published annually in the BreastScreen Australia monitoring report available on the AIHW website where they can be downloaded without charge. Supplementary data tables presenting data that are more detailed accompany each report and these are also available on the AIHW website where they can be downloaded without charge.

General enquiries about AIHW publications can be made to the Digital and Media Communications Unit on (02) 6244 1000 or via email to [email protected].

While many concepts in the BreastScreen Australia monitoring report are easy to interpret, other concepts and statistical calculations are more complex. All concepts are explained within the body of the report presenting these data, along with footnotes to provide further details and caveats. The appendixes provide additional detail on the data sources and classifications, and on the statistical methods used.

Breast cancer screening data are highly relevant for monitoring trends in breast screening participation and the detection of invasive breast cancer and DCIS, as well as other measures of program performance such as recall to assessment rates and sensitivity measures. The data are used for many purposes by policy makers and researchers, but are supplied and analysed specifically to monitor and inform BreastScreen Australia.
The majority of screening mammography performed in Australia is through BreastScreen Australia. However, a relatively small amount of screening mammography occurs through services other than BreastScreen Australia, which are not within the scope of these data.

All data provided by state and territory BreastScreen programs, once analysed, are supplied back for verification.

Women attending a BreastScreen service are able to self-report Indigenous status; this database field is therefore considered to be of high quality.

State and territory BreastScreen databases change every day, and not just because new records are added; existing records are changed if new, more precise information becomes available or if typographical errors are discovered by routine data checking procedures. As a result, the number of women participating, as well as DCIS and invasive breast cancer cases reported by the AIHW for any particular year may change slightly over time. Further data published by a jurisdictional BreastScreen program at a certain time may differ slightly from what is published by the AIHW at a different time.

Socioeconomic status Index of Relative Socio-economic Disadvantage (IRSD) rankings are calculated by Postal Area (POA) using a population-based method at the Australia-wide level. These ranked socioeconomic status POAs are then allocated to their relevant jurisdiction, meaning quintiles should contain similar socioeconomic groups across jurisdictions.

Socioeconomic status IRSD rankings are only measured at the time of the Australian Census of Population and Housing and are not available for approximately 18 months from the Census date. Consequently, socioeconomic status for a geographical area may be up to 6 years old and not an accurate representation of the status of residents at the time the data are analysed. In addition, IRSD is a measure of the average disadvantage of households in an area and the level of disadvantage of an individual household may vary significantly from the average.

An Australian Bureau of Statistics POA to remoteness correspondence and a POA to socioeconomic status correspondence are used to allocate persons screened to remoteness and socioeconomic status areas based on their postcode of residence. The remoteness (and socioeconomic status) to POA correspondences are based on postal areas, boundaries and classifications as at the year of the last Australian census, which may have been up to 5 years earlier, and boundaries, socioeconomic status and remoteness regions may have changed over time, creating inaccuracies. New postal areas defined since the last Census will not have valid remoteness or socioeconomic status correspondence data available as they will not exist in earlier correspondences.

Correspondences that convert POAs to PHN and Statistical Area geographies are also used. This may lead to some minor in accuracies in results, as some postcodes cross PHN and Statistical Area geographies. This error tends to be largest in areas where the boundaries of the two geographies do not align, or when mapping from larger to smaller areas. Correspondences rated as 'Poor' quality as determined by the Australian Bureau of Statistics are excluded from reporting. Records that cannot be converted by the correspondences are classified in an 'unknown' category.

BreastScreen data are reported and published annually by the AIHW.
Women attending a BreastScreen service are able to self-report Indigenous status; this database field is therefore considered to be of high quality. However, use of the ‘not stated’ category has changed substantially over time, which makes trend data difficult to interpret.
State and territory BreastScreen databases change every day, and not just because new records are added; existing records are changed if new, more precise information becomes available or if typographical errors are discovered by routine data checking procedures. As a result, the number of women participating, as well as ductal carcinoma and invasive breast cancer cases reported by the AIHW for any particular year may change slightly over time. Further data published by a jurisdictional BreastScreen program at a certain time may differ slightly from what is published by the AIHW at a different time.