AODTS NMDS coverage and data quality
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Introduction Overview of analysis variables and inclusion criteria State and territory ‘Assessment only’ data qualityThe Alcohol and Other Drug Treatment National Minimum Dataset (AODTS NMDS) includes government publicly funded alcohol and other drug treatment specialist services across Australia, including government and non-government agencies.
Data has been reported annually since 2003–04, with collection periods beginning on 1 July and ending on 30 June of the following year (financial years). It collects data on the number of closed treatment episodes provided to clients in a collection period (financial years), noting that the same client may receive multiple treatment episodes within or across collection periods. This report includes data on closed treatment episodes provided between 2013–14 to 2022–23, however, data coverage differs by variable (see historical data element changes).
In 2012–13, a statistical linkage key (SLK) was introduced to enable counting of individual clients who received treatment across collection periods. The SLK is constructed from information about the client’s date of birth, sex and selected letters of their name. 2012–13 was the pilot collection year for SLK-581 and has data quality issues (see the relevant Data Quality Statements for previous collection years for more detail).
Analysis of the SLK data showed that approximately 99% of national data contained a valid SLK in 2023–24, reflecting high response rates and improved SLK quality for all jurisdictions. An SLK in the AODTS NMDS is considered valid when all components are present and there are no missing/unknown components.
Although the AODTS NMDS collection covers the majority of publicly funded AOD treatment services, including government and non-government organisations, it is difficult to fully quantify the scope of AOD services in Australia and quantification does not provide a complete picture. Qualitative data such as narratives, and case examples are also required to gain a full sense of the experiences and pathways through treatment (The Department of Health and Aged Care 2019).
In 2023, it was estimated between 752,812 to 1,291,119 people met the criteria for a substance use disorder. In Australia it is estimated between 30% and 48% of the population would seek and benefit from AOD treatment. Resulting in a potential treatment population between 406,697 and 668,497 people. It was estimated in 2023,198,731 people would receive treatment in Australia. This highlights there is a continued significant unmet treatment needs of people with substance use disorders (Ritter and O’Reilly 2025).
Further details on scope, coverage and data quality are available from the AODTS NMDS Data Quality Statement and via the AIHW’s Metadata Online Registry (METEOR).
Overview of analysis variables and inclusion criteria
Table 6 provides an overview of variables included in this report and their relevant analysis criteria.
Type of data | Variable | Analysis criteria |
|---|---|---|
Client cohort-level data | Age | Clients aged less than 10 years and aged over 100 excluded. Clients with age missing excluded. |
Client cohort-level data | Sex | Clients with missing sex excluded. |
Client cohort-level data | Treatment episode history | Clients were excluded from the ‘Assessment only’ treatment cohort analysis if they:
|
Treatment episode-level data | Main treatment type | Episodes which occurred before a client’s first ‘Assessment only’ episode or after the client’s subsequent episode were excluded. |
Treatment episode-level data | Client type | Clients receiving treatment for others’ AOD use excluded. |
Treatment episode-level data | Principal drug of concern | No exclusions. |
Treatment episode-level data | Referral source | No exclusions. |
Treatment episode-level data | Delivery setting | No exclusions. |
Treatment episode-level data | Reason for cessation | No exclusions. |
Treatment episode-level data | Delivery setting | No exclusions. |
For more information on analysis variables used for statistical modelling methods see Analysis technical information.
The Alcohol and Other Drug Treatment Services National Minimum Data Set (AODTS NMDS) captures whether a client received a treatment episode for their own alcohol and other drug (AOD) use or another person’s AOD use.
Treatment episodes where a client received treatment for another person’s AOD use were excluded from analysis.
‘Assessment only’ treatment often includes an interview to assess client needs and facilitate appropriate service referrals. The associated data item and processes where Main treatment = ‘Assessment only’, need to be considered for analysis regarding the analytical capabilities and limitations outlined below:
Considerations:
- Differences in agency philosophy or service delivery models may influence how ‘Assessment only’ episodes are recorded and defined. For example,
- Some agencies perceive this element as a measure of ‘time waiting to enter selected treatment types’ regardless of the actual reason for treatment.
- The report captures treatment episodes within the AODTS system, clients may receive treatment from other health and/or welfare services.
- Where episodes are forced closed due to unintended lack of contact with the client for 3 months, the reason for cessation may be inconsistently recorded.
- There is evidence that the main treatment type ‘Assessment only’ is being used where clients have not returned to treatment, even where the intention of the episode was another treatment type; for example, where the assessment was for rehabilitation, but the client did not attend.
In the definition of the Main treatment element, an assessment is required before treatment which may not occur in these situations and where the main treatment type is ‘Assessment only’, there is no information on the result of that assessment.
The average annual rates of change or growth rates have been calculated as geometric rates:
Average rate of change = 
where:
Pn= value in the later time period
Po= value in the earlier time period
n = number of years between the 2 time periods.
A client's age, sex, and state or territory is derived from the first ‘Assessment only’ treatment episode they received between 2018–19 and 2023–24.
- The AODTS NMDS captures clients aged 10 and older at the time of their first treatment episode. Age is calculated as at the start of the first closed treatment episode for a client between 2018–19 and 2023–24.
- The AODTS NMDS records sex information as ‘male,’ ‘female,’ ‘another term,’ or ‘not stated’. Clients whose sex was recorded as ‘another term’ or ‘not stated’ are captured in the person total.
- A client's state or territory is defined by the treatment agency of where they received their first assessment only treatment episode between 2018–19 and 2023–24.
Clients are identified using a statistical linkage key (SLK-581). Every client in the AODTS NMDS is assigned a statistical linkage key (SLK-581). For more information, refer to the supplementary table footnotes and the SLK-581 guide for use.
An episode of treatment for alcohol and other drugs is the period of contact, with defined dates of commencement and cessation, between a client and a treatment provider or team of providers in which there is no change in the main treatment type or the principal drug of concern, and there has not been a non-planned absence of contact for greater than 3 months.
The main treatment type is the principal activity that is determined at assessment by the treatment provider to be necessary for the completion of the treatment plan for the client's alcohol or other drug use for their principal drug of concern.
Treatment types
The type of activity that is used to treat the client's alcohol or other drug use which include:
- Assessment only - refers to when there is no treatment provided to the client other than an overall assessment of their drug and/or alcohol use. An assessment encompasses treatment planning and referral. Service providers would normally include an Assessment component in all treatment types.
- Counselling – can include cognitive behaviour therapy, brief intervention, relapse intervention and motivational interviewing. It includes individual or group counselling.
- Information and education – the type of treatment provided to the client is related to a program, including written information or a psycho-educational intervention.
- Pharmacotherapy – where the client receives another type of treatment in the same treatment episode and includes drugs such as naltrexone, buprenorphine and methadone used as -maintenance therapies or relapse prevention for people who experience dependence on certain types of opioids. Where a pharmacotherapy is used for withdrawal, it is included in the withdrawal category. Due to the complexity of the pharmacotherapy sector, this report provides only limited information on agencies whose sole function is to provide pharmacotherapy.
- Rehabilitation – is an intensive structured treatment program that can occur in residential or non-residential settings and integrates a range of services and therapeutic activities that may include counselling, behavioural treatment approaches, recreational activities, social and community living skills, group work and relapse prevention. It focuses on supporting clients in stopping their drug use, and to prevent psychological, legal, financial, social and physical consequences of drug use. Rehabilitation can be delivered in several ways, including residential or non-residential treatment services, therapeutic communities and community-based rehabilitation services.
- Support and case management – support can include contacting an agency worker for emotional support, while case management is a structured form of ‘support’. It can assume a more holistic approach, taking into account all client needs (including general welfare needs) and it includes assessment, planning, case conferences, facilitated referral, monitoring and advocacy.
- Withdrawal management (detoxification) – includes medicated and non-medicated treatment in any delivery setting.
Other variables included for analysis include source of referral, reason for cessation, treatment delivery setting. For further information on these variables, refer to the Data and methods of the Alcohol and other drug treatment services in Australia annual report.
In this publication, crude rates were calculated using the ABS’s estimated resident population based on the 2021 Census at the midpoint of the data range: that is, rates for 2023–24 data were calculated using the estimated resident population at 31 December 2024.
The COVID-19 pandemic and the resulting Australian Government closure of the international border from 20 March 2020 caused significant disruptions to the usual Australian population trends. This report uses Australian Estimated Resident Population (ERP) estimates that reflect these disruptions.
In the year July 2020 to June 2021, the overall population growth was much smaller than the years prior and there was a relatively large decline in the population of Victoria. ABS reporting indicates these were primarily due to net-negative international migration, for further information, refer to National, state and territory population, June 2021.
Note that this change in the usual population trends may affect interpretation of statistics calculated from these ERPs. For example, rates and proportions may be greater than in previous years due to decreases in the denominator (population size) of some sub-populations.
Clients who received a previous treatment prior to an ‘Assessment only’ episode before entering the ‘Assessment only’ study population between 2018–19 and 2023–24 were flagged as having received a previous treatment. For further information on the methodology used to define these cohorts, see Technical notes: Scope and methodology.
Year clients entered study | No previous treatment | Previous treatment | Total |
|---|---|---|---|
2018–19 (Number of clients) | 27,275 | 6,358 | 33,633 |
2018–19 (Percentage) | 81% | 19% | 100% |
2019–20 (Number of clients) | 23,713 | 7,999 | 31,712 |
2019–20 (Percentage) | 75% | 25% | 100% |
2020–21 (Number of clients) | 22,796 | 9,130 | 31,926 |
2020–21 (Percentage) | 71% | 29% | 100% |
2021–22 (Number of clients) | 20,755 | 8,908 | 29,663 |
2021–22 (Percentage) | 70% | 30% | 100% |
2022–23 (Number of clients) | 21,298 | 8,876 | 30,174 |
2022–23 (Percentage) | 71% | 29% | 100% |
Total (Number of clients) | 115,837 | 41,271 | 157,108 |
Total (Percentage) | 74% | 26% | 100% |
The Alcohol and Other Drug Treatment Services National Minimum Data Set (AODTS NMDS) contains data on principal drugs of concern (PDOC) that are coded using the ABS’s Australian Standard Classification of Drugs of Concern (ASCDC) (ABS 2011).
The principal drug of concern (PDOC) is the main substance that the client stated as leading them to receive treatment from a specialised AOD treatment agency. PDOCs include alcohol as well as other drugs such as amphetamines, heroin, pharmaceuticals, ecstasy, and cocaine. Clients can only receive treatment for one PDOC per treatment episode, but clients may also receive multiple treatment episodes for different PDOCs.
This report uses the Australian Bureau of Statistics’ (ABS) Australian Statistical Geography Standard (ASGS) Edition 3 2021 Remoteness Structure to examine the distribution of clients receiving AOD treatment by remoteness area (ABS 2021).
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 road distance to population centres of various sizes. This allows a proxy to be created for relative access to services.
Examples of urban centres in each remoteness area are:
- Major cities: Canberra, Newcastle
- Inner regional: Hobart, Bendigo
- Outer regional: Cairns, Darwin
- Remote: Katherine, Mount Isa
- Very remote: Tennant Creek, Meekatharra.
For this report, the remoteness area is derived from the postcode of the client's last known home address before starting treatment. Where a postcode area covers multiple remoteness areas, the remoteness area with the highest proportion of the postcode donated is assigned. Due to small counts, data for Remote and very remote regions were aggregated.
Client location is derived from postcode of the client’s last known address before receiving treatment, which was collected for the first time in 2013–14. Postcode was calculated based on the first assessment only treatment episode for a client between 2018–19 and 2023–24.
Australian Bureau of Statistics (ABS) (2021). Australian Statistical Geography Standard Edition 3. Canberra: ABS.
Australian Institute of Health and Welfare (AIHW) (2024). Alcohol and other drug treatment services annual report AIHW, Australian Government, accessed 9 September 2024.
The Department of Health and Aged Care (2019). National Framework for Alcohol, Tobacco and Other Drug Treatment 2019–2029. Canberra: Commonwealth of Australia.
Ritter A, and O’Reilly K (2025). Unmet treatment need: The size of the gap for alcohol and other drugs in Australia. Drug Alcohol Rev. 2025; 44(3): 772–782. https://doi.org/10.1111/dar.14008
State and territory ‘Assessment only’ data quality
Across states and territories, there is variations in service structures, and collection practices, this should be considered when making comparisons between states and territories. Due to these methods, the data item ‘Assessment only’ maybe used differently across states and territories. For more information see state and territory data quality.
State/territory | Administrative features of ‘Assessment only’ |
|---|---|
New South Wales | In New South Wales, an Assessment only episode is provided where there is no service provided to the client other than a clinical assessment, involving the comprehensive gathering of information to determine the severity of the person’s alcohol and/or other drug use, resulting in the determination of the most appropriate form of service. It is noted that service contacts would generally include an assessment component. |
Victoria | For ‘Assessment only’, Victoria reports every completed service event that has a service stream of ‘comprehensive assessment’ regardless of the number of these occurring for the same client over the reporting period. If there is no assessment service event reported in the same AODTS NMDS period as a related reported treatment service event, then no corresponding assessment record will be reported. In addition, only completed service events are reported regardless of service event type. That is assessments with no completion dates will not be reported. |
Queensland | The Queensland Health Mental Health, Alcohol and Other Drugs (MHAOD) clinical information system has several concepts that are transformed to meet the AODTS NMDS counting unit of a Treatment Episode. The concept of “Service Sector” is used to differentiate mental health from alcohol and other drugs services within CIMHA for functionality purposes. Referral - captures details regarding the consumers entry into the mental health service OR alcohol and other drugs service within a CIMHA Network. Service Episode - is defined as a continuous period of mental health service OR alcohol and other drugs service for a consumer within the same Service Type, Service Sector and Network. A new service episode starts at the conclusion of the consumer’s first face to face assessment if further face to face services for the consumer are planned by the Network (within the next 90 days) for the same Service Sector. Engagement - is a course of treatment with specific data collection requirements that cannot be captured by other parts of the application. At present there are three (3) types of Engagement that can be entered for consumers in CIMHA:
‘Assessment only’ treatment episodes are transformed from within a referral where a Provision of Service (POS) has been provided, the referral has been ended, no service episode or engagement has commenced, and the end reason of the referral is not ‘Lost to follow-up’. ‘Assessment only’ is not provided when a client has been referred to the AOD service and following assessment, a service episode is commenced for the client. When the service episode is closed, both the referral and the service episode components are transformed into a single treatment episode for reporting to the AODTS NMDS. |
Western Australia | An assessment encompasses treatment planning and referral and applies only when there is no other treatment provided to the client other than an overall assessment. |
South Australia | At Assessment, the Service Provider will work with the client or their clinical notes (client absent) to understand their AOD needs and determine the next course of action for the presenting AOD concern. Prior to an Assessment, comprehensive screening (triage) may have taken place which deemed them eligible for treatment (but not necessarily suitable) with the Service Provider. The main treatment type ‘’Assessment only’ flag is used when at Assessment:
For the above, the client is not generally expected to continue in treatment with the service provider and therefore, a subsequent outpatient appointment is not booked for the client following assessment. An ‘Assessment only’ episode is not flagged as such for clients:
|
Tasmania | In Tasmania:
|
Australian Capital Territory | When there is no treatment provided to the client other than an overall assessment of the extent and nature of their drug and alcohol use. An assessment encompasses treatment planning and referral. |
Northern Territory | ‘Assessment only’ refers to a service contact undertaken solely for the purpose of completing a comprehensive assessment to determine a client’s suitability for treatment or for commencing another episode of care. The purpose of an assessment remains unchanged regardless of the outcome of the assessment. Uncommonly, some non-government organisation providers may not enter an ‘Assessment only’ episode as an assessment, as it may have already occurred with the referring agency |