Data and methods

Age

Age is calculated as at 30 June of the collection year.

Agency remoteness area

Dosing points have been classified according to their remoteness area (RA) as defined by the Australian Statistical Geography Standard (ASGS) Remoteness Structure (ABS 2016). This structure allows areas that share common characteristics of remoteness to be classified into broad geographic regions of Australia. These areas are:

  • Major cities
  • Inner regional
  • Outer regional
  • Remote
  • Very remote.

The Remoteness Structure divides each state and territory into several regions based on their relative access to services.

Examples of places that are considered Major cities in the ASGS classification include Sydney, Canberra and Newcastle. Hobart and Bendigo are Inner regional areas and Cairns and Darwin are Outer regional areas. Katherine and Mount Isa are Remote areas, and Tennant Creek and Meekatharra are Very remote.

Using this classification, dosing points were assigned to an RA based on their recorded Statistical Area Level 2 (SA2) code. Some SAs are split between multiple remoteness areas. This may have impacted the calculation of rates.

Confidentiality

The Australian Institute of Health and Welfare (AIHW) has strict confidentiality policies which have their basis in Section 29 of the Australian Institute of Health and Welfare Act 1987 (the AIHW Act) and the Privacy Act 1988 (the Privacy Act). Cells in supplementary tables may be suppressed for either confidentiality reasons or where estimates are based on small numbers, resulting in low reliability. Information that results in attribute disclosure will be suppressed unless agreement from the particular data provider to publish the data has been reached. Information on the AIHW's Privacy policy is available on the privacy page.

Data coverage

Queensland data were not available for the NOPSAD collection in 2021. This was a result of the implementation of a new real-time prescription monitoring system (QScript) and the commencement of the new Medicines and Poisons Act 2019. In 2021, collection of medicines information transitioned from the Monitoring of Drugs of Dependence System database to the new QScript system. This transition resulted in significant changes to the data being collected for the Queensland Opioid Treatment Program.

Population estimates used for rates calculations

All rates in this report, including historical rates, have been calculated using population estimates based on the 2016 Census. All Indigenous rates in this report are calculated using the Indigenous population estimates and projections, based on the 2016 Census.

In 2021, the increase in the total rate of Indigenous clients per 10,000 people may relate to several factors, including:

  • Improved coding of Indigenous status in Victoria, leading to an increase in the number of Indigenous clients overall.
  • The exclusion of Queensland data from Indigenous population estimates (28% of Australia's Indigenous population resides in Queensland), leading to a decrease in the estimated population for Indigenous people.

This may result in increased rates even if the number of clients did not increase.

Population rates

Crude rates are calculated using the Australian Bureau of Statistics estimated resident population (ERP) as at 30 June of each collection year. Rates for 2021 data were calculated using the preliminary ERP at 30 June 2021, with the exception of remoteness rates which were calculated using the preliminary ERP at 30 June 2020.

In the year ending 30 June 2021, the estimated residential population in Victoria decreased. This decline was driven by a relatively large net negative overseas migration, likely due to the closure of Australia's international border in March 2020 in response to the COVID-19 pandemic. This may result in increased rates even if the number of clients did not increase. Other states and territories were also impacted by border closures; caution should be taken when comparing population data for 2021 with previous years.

Sex

The classification of Sex ‘Other’ was introduced into the NOPSAD collection for the first time in 2021. These data are not reported in text due to small numbers in this category, but are included in supplementary data tables S7 and S8. For more information, see the NOPSAD Data Quality Statement.

Trends

Trend data may differ from data published in previous versions of the National Opioid Pharmacotherapy Statistics Annual Data collection report due to data revisions. Queensland data were not available in 2021, therefore caution should be taken when comparing 2021 data with previous years as these include data for Queensland.

References

ABS (Australian Bureau of Statistics) (2016) The ASGS remoteness structure, ABS, Australian Government, accessed 14 January 2022.