National Study of Mental Health and Wellbeing methodology

The National Study of Mental Health and Wellbeing (NSMHW) is a component of the wider Intergenerational Health and Mental Health Study (IHMHS) funded by the Australian Government Department of Health and Aged Care.

Data for the NSMHW was collected in the Survey of Health and Wellbeing (SHWB) which was conducted by the Australian Bureau of Statistics (ABS). The first cohort was conducted between December 2020 and July 2021. The second cohort was conducted between December 2021 and October 2022.

The main aims of the NSMHW are to provide information in five key areas:

• How many Australians have mental disorders?
• What is the impact of these disorders?
• How many people have used services and what are the key factors affecting this?
• Are services making a difference to the lives of people experiencing problems with their mental health?
• How many Australians have a lived experience of suicide and what services have they used?

Key topics included:

• lifetime and 12-month prevalence of selected mental disorders
• level of impairment for these disorders
• health services used for mental health problems, such as consultations with health practitioners or visits to hospital
• suicidality and self-harm behaviours
• demographic and socio-economic characteristics of people.

The Cohort 1 and Cohort 2 sample have been combined to create a 2020–2022 dataset. Estimates presented in this publication are derived from the combined sample. Cohorts 1 and 2 are also available as separate datasets. Estimates from the individual cohorts will not match estimates derived from the combined sample. Information relating to each of the cohorts as well as the combined 2020–2022 sample is presented below.

The scope of the study included:

• all usual residents in Australia aged 16–85 years living in private dwellings
• both urban and rural areas in all states and territories, except for Very Remote parts of Australia and discrete Aboriginal and Torres Strait Islander communities.

The study excluded the following people:

• visitors to private dwellings
• overseas visitors who have not been working or studying in Australia for 12 months or more, or do not intend to do so
• members of non-Australian defence forces stationed in Australia and their dependants
• non-Australian diplomats, diplomatic staff, and members of their households 
• people who usually live in non-private dwellings, such as hotels, motels, hostels, hospitals, nursing homes and short-stay caravan parks (people in long-stay caravan parks, manufactured home estates and marinas are in scope)
• people in Very Remote areas
• discrete Aboriginal and Torres Strait Islander communities.

The exclusion of people living in Very Remote areas and discrete Aboriginal and Torres Strait Islander communities is unlikely to impact national estimates. It will only have a minor impact on any aggregate estimates produced for individual states and territories, except the Northern Territory where the excluded population accounts for around 21% of people.

The exclusion of residents in special dwellings (e.g., hotels, boarding houses, and institutions) and homeless people means the results are likely to underestimate the prevalence of mental disorders in the Australian population.

Households were randomly selected to participate in the study. One person aged 16–85 years was randomly selected in each household to complete the study questionnaire. If the randomly selected person was aged 16–17 years, parental consent was sought for the interview to proceed.

The sample was designed to target people aged 16–24 years to improve estimates for this age group. People in this age group had a higher probability of being selected in the sample.

Cohort 1

There were 5,554 fully responding households in Cohort 1 of the study, a response rate of 57.1%.

Cohort 2

There were 10,339 fully responding households in Cohort 2 of the study, a response rate of 49.6%.

Cohort 1 and Cohort 2 combined

Some respondents were unable or unwilling to provide a response to certain questions. The records for these people were retained in the sample and the missing values were recorded as 'Not stated', 'Don't know' or ‘Refusal’. No imputation was undertaken for these missing values.

Cohort 1 of the study was collected over an 8-month period from 5 December 2020 to 31 July 2021. Cohort 2 of the study was collected over an 11-month period from 4 December 2021 to 31 October 2022. The majority of households were required to complete a survey face-to-face with an ABS Interviewer. Interviews were conducted during periods when circumstances in individual jurisdictions permitted face-to-face interviewing according to relevant jurisdictional public health orders and restrictions. During the collection of Cohort 2, 446 households (4.3% of Cohort 2 fully responding households) completed the survey via a video call with an ABS Interviewer.

Information collected in the study includes:

• Household Information, which was completed by any responsible adult in the household aged 18 years or over. The Household Information component of the study collected basic demographic information about all usual residents of the household, including those aged under 15 years, as well as information about the dwelling and household income
• Individual Questionnaire, which was completed by one randomly selected person in the household aged 16–85 years. The random selection was automatically performed upon completion of the Household Form.

The study used the World Mental Health Survey Initiative version of the World Health Organization's (WHO) Composite International Diagnostic Interview, version 3.0 (WMH-CIDI 3.0).

A group of ABS officers were trained in the use of the WMH-CIDI 3.0 by WHO accredited trainers. These officers then provided training to experienced ABS Interviewers, as part of a comprehensive four-day training program, which also included sensitivity training and field procedures.

While most of the study was based on the WMH-CIDI 3.0, modules such as Health Service Utilisation were designed in consultation with subject matter experts from academic institutions and staff from the Department of Health and Aged Care. New study content was tested by the ABS.

The study was designed to provide lifetime prevalence estimates for mental disorders by asking respondents about experiences throughout their lifetime. 12-month diagnoses were derived based on lifetime diagnosis and the presence of symptoms of that disorder in the 12 months prior to the survey interview. The full diagnostic criteria were not assessed within the 12-month timeframe.

The study included mental disorders that:

• were expected to affect more than 1% of the population
• were able to be diagnosed through the WMH-CIDI 3.0
• were likely to be identified through a household survey.

The WMH-CIDI 3.0 was also used to collect information on:

• the onset of symptoms and mental disorders
• the recency of symptoms and mental disorders
• the persistence or duration of symptoms and mental disorders
• the impact of mental disorders on home management, work life, relationships, and social life
• treatment-seeking and access to helpful treatment.

Due to the sensitivity of some content, the mental health component of the study was conducted on a voluntary basis.

The ABS would like to thank all participants for their involvement in the National Study of Mental Health and Wellbeing. The information collected is critical to mental health policy, program development and evaluation in Australia.

The study collected the following content:

• Demographics including age, sex at birth, gender, variations of sex characteristics, and sexual orientation, country of birth, main language spoken, and marital status
• Household details including household composition, tenure type, landlord type, number of bedrooms, and household income
• Socio-economic characteristics of people including labour force status, educational attainment, and personal income
• General health and wellbeing including self-assessed health status, psychological distress, smoking, long term health conditions, social connectedness, and functioning
• Mental disorders including Depression, Mania, Panic Disorder, Social Phobia, Agoraphobia, Generalised Anxiety Disorder, Substance Use, Obsessive-Compulsive Disorder, Post-Traumatic Stress Disorder
• Suicidality
• Self-harm
• Disordered eating
• Use of health and social support services.

The 2020–2022 National Study of Mental Health and Wellbeing is the first ABS collection to use the Standard for Sex, Gender, Variations of Sex Characteristics and Sexual Orientation Variables, 2020. Data in this publication are presented using the Sex variable. When a small number of responses are recorded in any output category, outputs may be suppressed or combined into other categories due to confidentiality and statistical issues. A small number of people in the study reported having a term other than male or female recorded as their sex at birth. Estimates for people whose sex at birth is neither male or female are not able to be output as a separate category but they are included in the estimates for total Persons.

See the Data Item List for full details of content collected for the 2020–2022 NSMHW.

The ABS previously conducted this survey in 2007. The 2020–2022 study was designed to be broadly comparable with 2007.

It used the WMH-CIDI 3.0 questionnaire modules used in 2007 and collected them in the same order as they were collected in 2007. Data collected using the WMH-CIDI 3.0 modules are therefore comparable between 2020–2022 and 2007.

Many of the non-diagnostic topics and the order in which they were collected in 2020–2022 differs from that in 2007. Some topics collected in 2007 were removed and new topics were added. Other topics changed significantly between 2020–2022 and 2007. For example, demographic and socio-economic modules were updated to align with current ABS standards and commonly used ABS questions and data items. Data for non-diagnostic topics may not be comparable between 2020–2022 and 2007.

Please see the Data Item Lists for each collection for full details.

Due to the change in questions used to collect physical health conditions in 2020–2022, the comorbidity of mental disorders and physical health conditions is not comparable with 2007. In 2020–2022 the comorbidity of mental disorders and National Health Priority Area physical conditions data items were re-labelled as comorbidity of mental disorders and 'selected chronic physical conditions'. The selected chronic physical conditions are cancer, stroke, heart disease, arthritis and diabetes.

2020–2022 DSM-IV Anxiety Disorders include Agoraphobia with/without Panic Disorder rather than Agoraphobia without Panic Disorder which was included in 2007. This also impacts all dependent data items, for example DSM-IV Any Mental Disorder.

The diagnoses of mental disorders are based on the WMH-CIDI 3.0 algorithms. The algorithms operationalise criteria from two classification systems: the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV); and the WHO International Classification of Diseases, Tenth Revision (ICD-10).

The version of the algorithms used for 2020–2022 was provided by the WHO in 2020. The algorithms are comparable with the version used for 2007 with the following exceptions:

ICD-10 Post-Traumatic Stress Disorder (PTSD)

ICD criteria B Part 2 has been updated: Group 2 reactions (unwanted memories, unpleasant dreams, flashbacks, getting very upset when reminded of it, physical reactions) must have occurred at least once a month. The version of the diagnostic algorithms used for the 2007 survey did not include the once-a-month persistence criterion.

ICD criteria D Part 2 has been updated: Persistent symptoms of increased psychological sensitivity and arousal shown by any two of the following: difficulty in falling or staying asleep, irritability or outbursts of anger, difficulty in concentrating, hypervigilance, exaggerated startle response; not present before exposure to the stressor, and must have occurred at least once a month. The version of the diagnostic algorithms used for the 2007 survey did not include the once-a-month persistence criterion.

Lifetime and 12-month prevalence data items for ICD-10 PTSD are therefore not comparable between 2020–2022 and 2007.

ICD-10 Obsessive-Compulsive Disorder (OCD)

For an ICD-10 lifetime diagnosis of OCD, obsessions and/or compulsions must be present on most days for at least two weeks. In 2007, the 12-month diagnosis was derived from the lifetime diagnosis including the criterion that disorder symptoms must have been present on most days for at least two weeks or longer in the 12 months prior to the survey interview. The version of the algorithms used for 2020–2022 did not include the two-week persistence as a condition for meeting 12-month diagnosis. 12-month diagnosis in 2020–2022 is derived based on lifetime OCD diagnosis with the presence of OCD symptoms, for any duration, in the past 12 months.

12-month prevalence data items for ICD-10 OCD are therefore not comparable between 2020–2022 and 2007.

Both Post-Traumatic Stress Disorder and Obsessive-Compulsive Disorder are classified as Anxiety disorders. Consequently, the ICD-10 lifetime and 12-month Anxiety disorders data items and the ICD-10 lifetime and 12-month Mental disorders data items are also not comparable between 2020–2022 and 2007.

2007 re-derived data items

To enable comparison between 2020-2022 and 2007, selected ICD-10 Post-Traumatic Stress Disorder, ICD-10 Obsessive-Compulsive Disorder, ICD-10 Anxiety disorders, and ICD-10 Mental disorders data items, as well as the associated ICD-10 comorbidity and severity data items, have been re-derived using the 2020 definitions. These have been added to the 2007 detailed microdata file. Selected estimates have also been backcast and published in the National Survey of Mental Health and Wellbeing, 2007 Summary of Results.

The Country of birth of father and Country of birth of mother data items are only available for Cohort 2.

The WMH-CIDI 3.0 contains some open-ended questions, for which there are no predetermined responses. Open-ended questions are used to determine whether a respondent met the criteria for diagnosis of a mental disorder and probe causes of a particular episode or symptom. Responses are then used to eliminate cases where there is a clear physical cause. An example is in a Panic Disorder diagnosis. If the respondent has described symptoms such as a racing heart and says a heart attack was the physical reason for their symptoms, they are not diagnosed with a Panic Disorder. As part of the processing procedures set out for the WMH-CIDI 3.0, responses provided to these open-ended questions were coded by a suitably qualified person.

As only a sample of people in Australia were surveyed, their results needed to be converted into estimates for the entire population. This was done through a process called weighting. 

• Each person or household is given a number (known as a weight) to reflect how many people or households they represent in the entire population.
• A person or household’s initial weight is based on their probability of being selected in the sample. For example, if the probability of being selected was one in 45, then the person would have an initial weight of 45 (that is, they would represent 45 people).

The person and household level weights are then calibrated to align with independent estimates of the in-scope population, referred to as ‘benchmarks’. The benchmarks use additional information about the population to ensure that:

• people or households in the sample represent people or households that are similar to them
• the study estimates reflect the distribution of the entire population, not the sample.

The initial weights for Cohort 1 were calibrated to the estimated resident population (ERP) as at March 2021. The Australian population as at March 2021 aged 16 to 85 years was 19,644,025 (after exclusion of people living in non-private dwellings, Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities).

The initial weights for Cohort 2 and the combined 2020–2022 sample were calibrated to the estimated resident population (ERP) as at March 2022. The Australian population as at March 2022 aged 16–85 years was 19,828,348 (after exclusion of people living in non-private dwellings, Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities).

Analysis showed that the standard weighting approach did not adequately compensate for under-coverage in both the Cohort 1 and Cohort 2 samples for variables such as educational attainment, household composition, and labour force status, when compared to other ABS surveys. Therefore, additional benchmarks were incorporated into the weighting strategy. Additional benchmarks were obtained from the ABS monthly Labour Force Survey (December 2020 to October 2022) for labour force status, educational attainment, and household composition. 

For Cohort 1, these benchmarks were aligned to the estimated resident population aged 16-85 years, who were living in private dwellings in each state and territory, excluding Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities,  as at 31 March 2021.

For Cohort 2 and the combined 2020-2022 sample, these benchmarks were aligned to the estimated resident population aged 16–85 years, who were living in private dwellings in each state and territory, excluding Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities, as at 31 March 2022.

A two-phase estimation approach was used to adjust for under-coverage that was observed between the population who completed only the compulsory section of the survey and the population who completed both the compulsory and voluntary sections of the survey. Survey weights were adjusted to ensure that estimates from the voluntary section of the survey for the grouped Kessler score, sexual orientation and English language proficiency aligned with estimates from the full sample, i.e., compulsory and voluntary combined.

This weighting approach has been implemented for each of the cohorts and the combined 2020–2022 sample.

Sample counts and weighted estimates for the 2020–2022 (combined Cohort 1 and Cohort 2) sample are presented in the table below.

Sample counts and weighted estimates for Cohort 1 (2020-21) are presented in the table below.

Sample counts and weighted estimates for Cohort 2 (2021-22) are presented in the table below.

Reliability of estimates

Two types of error are possible in estimates based on a sample survey:

• non-sampling error   
• sampling error.

This release presents limited estimates for states and territories. The NSMHW sample was designed to provide reliable national-level estimates. While estimates are available for each state and territory, the sample size does not allow for detailed analysis and care should be taken if comparing states and territories.

Data Cubes (spreadsheets) in this release present tables of estimates, proportions, and their associated measures of error. A data item list is also available.

Detailed microdata is also available on DataLab for users who want to undertake complex analysis of microdata in the secure ABS environment.

The Census and Statistics Act 1905 authorises the ABS to collect statistical information and requires that information is not published in a way that could identify a particular person or organisation. The ABS must make sure that information about individual respondents cannot be derived from published data.

To minimise the risk of identifying individuals in aggregate statistics, a technique called perturbation is used to randomly adjust cell values. Perturbation involves small random adjustment of the statistics which have a negligible impact on the underlying pattern. This is considered the most satisfactory technique for avoiding the release of identifiable data while maximising the range of information that can be released. After perturbation, a given published cell value will be consistent across all tables. However, adding up cell values in Data Cubes to derive a total may give a slightly different result to the published totals.

The WHO WMH-CIDI 3.0 provides an assessment of mental disorders based on the definitions and criteria of two classification systems: the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV); and the WHO International Classification of Diseases, Tenth Revision (ICD-10).

Each classification system lists sets of criteria that are necessary for diagnosis. The criteria specify the nature and number of symptoms; the level of distress or impairment; and the exclusion of cases where symptoms can be directly attributed to general medical conditions, such as a physical injury, or to substances, such as alcohol. Variations in the diagnostic assessment criteria for the ICD-10 and the DSM-IV may give differing estimates for the overall prevalence of mental disorder, as well as for specific disorders.

As not all modules contained in the WMH-CIDI 3.0 were collected in the study it was necessary to tailor the diagnostic algorithms. Information about modules not operationalised and potential impacts on diagnoses is included below with the descriptions of the diagnostic criteria according to the ICD-10 and DSM-IV mental disorders used in the WMH-CIDI 3.0.

For this collection, mental disorders have been aggregated to three main disorder groups. The three disorder groups have then been aggregated to an overall mental disorders group.

The disorders included in the aggregate ‘ICD-10 Anxiety disorders’ group data items are Panic Disorder, Agoraphobia with/without Panic Disorder, Social Phobia, Generalised Anxiety Disorder, Obsessive-Compulsive Disorder, and Post-Traumatic Stress Disorder.

The disorders included in the aggregate ‘DSM-IV Anxiety disorders’ group data items are Panic Disorder, Agoraphobia with/without Panic Disorder, Social Phobia, Generalised Anxiety Disorder, Obsessive-Compulsive Disorder, and Post-Traumatic Stress Disorder.

The disorders included in the aggregate ‘ICD-10 Affective disorders’ group data items are Depressive Episode (which includes Minor Depressive Episode, Moderate Depressive Episode and Major Depressive Episode), Dysthymia, and Bipolar Affective Disorder.

The disorders included in the aggregate ‘DSM-IV Affective disorders’ group data items are Major Depressive Disorder (which includes Major Depressive Episode), Dysthymia, Bipolar I Disorder and Bipolar II Disorder.

The disorders included in the aggregate ‘ICD-10 Substance Use disorders (Australian version)’ group data items are Alcohol Harmful Use, Alcohol Dependence, Drug Harmful Use (Australian version), and Drug Dependence (Australian version).

The disorders included in the aggregate ‘DSM-IV Substance Use disorders (Australian version)’ group data items are Alcohol Abuse, Alcohol Dependence, Drug Abuse (Australian version), and Drug Dependence (Australian version).

The ‘ICD-10 Any Mental Health Disorder’ data items includes ‘ICD-10 Anxiety Disorder’, ‘ICD-10 Affective Disorder’, and ‘ICD-10 Substance Use Disorder’. 

The ‘DSM-IV Any Mental Health Disorder’ data items includes ‘DSM-IV Anxiety Disorder’, ‘DSM-IV Affective Disorder’, and ‘DSM-IV Substance Use Disorder’.

The classification system for some of the mental disorders contain diagnostic exclusion rules. Where a person has symptoms that meet diagnostic criteria for more than one of these particular disorders, the exclusion rules give precedence to one diagnosis over another. It is assumed that the symptoms reported are accounted for by the disorder given precedence. These exclusion rules are built into the diagnostic algorithms.

The WMH-CIDI 3.0 includes two versions of the diagnoses in the algorithms for a number of the mental disorders: a 'with hierarchy' version and a 'without hierarchy' version. The 'with hierarchy' version specifies the full diagnostic criteria consistent with the ICD-10 or DSM-IV classification system (i.e., the exclusion criteria are enforced).

One example of a disorder specified with and without hierarchy is Alcohol Harmful Use. ICD-10 states that for diagnostic criteria for Harmful Use to be met, criteria cannot be met for Dependence on the same substance during the same time period. Therefore, the ‘with hierarchy’ version of Alcohol Harmful Use will exclude cases where Alcohol Dependence has been established for the same time period. The ‘without hierarchy’ version includes all cases of Alcohol Harmful Use regardless of coexisting Alcohol Dependence. Note that a person can meet criteria for Alcohol Dependence and the hierarchical version of Alcohol Harmful Use if there is no overlap in time between the two disorders.

Data in this publication are presented using the ICD-10 classification system. Prevalence rates are presented with hierarchy rules applied.

The mental disorders specified with and without hierarchy are outlined below and an example of the differences in prevalence rates with and without hierarchy rules applied is provided in the following table.

The following information provides descriptions of the WMH-CIDI 3.0 diagnostic assessment criteria according to the WHO International Classification of Diseases, Tenth Revision (ICD-10). Not all exclusions specified in the ICD-10 were able to be addressed in the study. Therefore, some of the descriptions differ from the ICD-10.

Anxiety disorders

Anxiety disorders generally involve feelings of tension, distress, or nervousness. A person may avoid, or endure with dread, situations which cause these types of feelings. The disorders within this group assessed in the study are:

• Panic Disorder
• Agoraphobia
• Social Phobia
• Generalised Anxiety Disorder (GAD)
• Obsessive-Compulsive Disorder (OCD)
• Post-Traumatic Stress Disorder (PTSD).

Affective disorders

Affective disorders involve mood disturbance or change in affect. Most of these disorders tend to be recurrent and the onset of individual episodes can often be related to stressful events or situations. Disorders within this group include:

• Depressive Episode
• Dysthymia
• Bipolar Affective Disorder (of which Hypomania and Mania are components).

Substance Use disorders

Substance Use Disorders involve the Harmful Use and/or Dependence on alcohol and/or drugs. The misuse of drugs, defined as the use of illicit substances and the misuse of prescribed medicines, included the following drug categories:

• opioids
• cannabinoids
• sedatives
• stimulants.

Alcohol Use disorders　

Detailed questions about alcohol use were only asked if the person had at least 12 alcoholic drinks in the 12 months prior to interview.

Drug Use disorders　

Assessment for Harmful Use and Dependence was only conducted if use of an illicit drug or misuse of a prescription medication occurred more than five times in the respondents' lifetime. A general assessment was made for Harmful Use and Dependence of any drugs as well as separate assessments of Harmful Use and Dependence for four specific categories of drug categories:

• opioids (e.g., heroin, methadone, oxycodone)
• cannabinoids (e.g., marijuana, hashish, synthetic cannabinoids)
• sedatives (e.g., barbiturates, Serepax, sleeping pills, Valium)
• stimulants (e.g., amphetamines, Dexedrine, speed).

The following information provides descriptions of the WMH-CIDI 3.0 diagnostic assessment criteria according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Note that not all exclusions specified in the DSM-IV were able to be addressed in the NSMHW. Therefore, some of the descriptions outlined differ from the DSM-IV.

DSM-IV Anxiety disorders

Anxiety disorders generally involve feelings of tension, distress, or nervousness. A person may avoid, or endure with dread, situations which cause these types of feelings. The disorders within this group assessed in the study are:

• Panic Disorder
• Agoraphobia
• Social Phobia
• Generalised Anxiety Disorder (GAD)
• Obsessive-Compulsive Disorder (OCD)
• Post-Traumatic Stress Disorder (PTSD).

DSM-IV Affective disorders

Affective disorders involve mood disturbance or change in affect. Most of these disorders tend to be recurrent and the onset of individual episodes can often be related to stressful events or situations. Disorders within this group include:

• Major Depressive Episode
• Major and Minor Depressive Disorders
• Recurrent Brief Depression
• Dysthymic Disorder
• Bipolar I and II Disorders (of which Hypomanic and Manic Episodes are components).

DSM-IV Substance Use disorders

The NSMHW collected information on the abuse and dependence on alcohol and other substances. Detailed questions about alcohol use were only asked if the person had at least 12 standard alcoholic drinks in a 12-month period. A standard drink contains 12.5ml of alcohol. The serving size determines the number of standard drinks per serve.

Detailed questions about drug abuse and dependence were only asked if a person had misused prescription medication more than five times in their lifetime; or used the same type of illicit drug (e.g., speed, ecstasy, marijuana) more than five times in their lifetime.

The misuse of prescription medication includes using medicine/s without the recommendation of a health professional, overusing medicines, or taking medicines for any other reason than as prescribed.

Drugs were categorised by four main types:

• opioids (e.g., heroin, methadone)
• cannabinoids (e.g., marijuana)
• sedatives (e.g., Serepax, Valium)
• stimulants (e.g., amphetamines, speed).

Drug Use disorders

As outlined earlier, Substance Abuse and Dependence were only assessed where a person had misused prescription medication more than five times in their lifetime or used the same type of illicit drug (e.g., speed, ecstasy, marijuana) more than five times in their lifetime.

The level of severity of impairment was calculated for people who were diagnosed with a lifetime mental disorder and had symptoms in the 12 months prior to interview. The severity measure draws upon a number of criteria, based on the endorsement of particular questions in the survey interview.

The responses to these questions were used to provide an overall indication of the severity of impairment, by the following three levels:

• severe
• moderate
• mild.

Several versions of the severity measure have been created, including:

• a WMH-CIDI 3.0 version
• a New Zealand version
• an Australian version.

Both the WMH-CIDI 3.0 version and the New Zealand version of severity are based on the DSM-IV. Adjustments were made to the severity measure for both versions to enable a severity calculation for the ICD-10. The Australian version was adapted from the New Zealand version and includes both DSM-IV and ICD-10 calculations. The criteria used to determine the level of severity for all versions are provided below, along with any additional criteria for each of the specific versions.

The National Comorbidity Survey Replication (NCS-R) was conducted in the United States of America in 2001-02. The survey had a sample of approximately 10,000 respondents aged 18 years and over. The survey made an overall assessment of functional impairment using several definitions of severity. Subsequent surveys have adopted an approach which uses a 'predicted' Global Assessment of Functioning (GAF) Score. For this survey, the predicted GAF Score was calculated using the maximum number of days out of role, and the scores from the Sheehan Disability Scale domains.

People with lived experience of suicide may have personally experienced suicidal thoughts and behaviours or may be close to someone who has experienced suicidal thoughts and behaviours or taken their life.

Suicidal thoughts and behaviours

In the study, people were asked about suicidal thoughts and behaviours in their lifetime and in the 12 months prior to interview. Suicidal thoughts and behaviours include:

• serious thoughts about taking one’s life
• plans to take one’s life
• attempts to take one’s life.

A person must have said they had seriously thought about taking their life to be asked if they had made a plan or attempt.

People were asked a series of questions including the age these experiences first and last occurred, and whether they sought medical assistance or mental health care.

People were also asked if they have been close to someone who attempted to or took their own life and whether they sought support services for themselves.

Suicidal thoughts and behaviours related to Depression

The Depression module contained questions which asked whether a person had:

• seriously thought about taking their life
• made a plan to take their life
• attempted to take their life.

The suicide questions in the Depression module refer to the period of several days/two weeks or longer during the episode when the person's symptoms (sadness, discouragement, loss of interest and other problems) were most severe and frequent.

Comparability with 2007

The 2020–2022 study updated the terminology used for questions about suicide. Questions used the phrase ‘take your life’. In 2007, questions about suicide used the phrase ‘committing suicide’.

Questions on use of services were asked for the first time in 2020–2022.

Self-harm is defined as someone intentionally harming themselves, but without the intention of taking their life.

In the study, people were asked about self-harming in their lifetime and in the 12 months prior to interview. If endorsed, they were also asked about whether they received any medical help for their injuries.

Questions on self-harm were asked for the first time in 2020–2022.

Aspects of disordered eating were collected in the study however are not estimates of the prevalence of eating disorders in the population.

In the study, people were asked about experiences of binge eating in their lifetime and in the last 12 months.

Eating binges were defined as a person eating a large amount of food during a short period, like two hours. A large amount was more than what most people would eat given the circumstances.

Eating binges must have been accompanied by a feeling of loss of control during which a person felt that they were unable to prevent themselves from eating or felt unable to stop eating once started and must have occurred at least once a week for several months or longer.

People were also asked to rate the importance their weight and/or shape has to the way they think about themselves as a person using the following scale:

1. Not at all important
2. Slightly important
3. Moderately important
4. Very important
5. Extremely important

Questions on disordered eating were asked for the first time in 2020–2022.

Within each of the mental disorder modules, the study collected broad information on people's consultations with health professionals and any overnight hospital admissions.

Information was also collected through a separate service utilisation module containing questions on services used for mental health problems.

Health service utilisation relates to services used for mental health problems in the 12 months prior to interview. While people were asked whether their use of health services related to a mental health problem, it is not possible to directly link this with specific mental disorders. A mental health problem in this context may relate to stress, worry, sadness, or to any issue identified by the person, regardless of whether they met criteria for a mental disorder. Also, the treatment sought and/or received may relate to a mental disorder not collected in the study, such as an eating disorder. Therefore, while it is possible to analyse the use of health services by people with a mental disorder, it is not possible to directly link service use with specific mental disorders.

For the 2020–2022 NSMHW, mental health-related medications data was sourced from the Pharmaceutical Benefits Scheme (PBS) instead of being collected directly from survey respondents. To enable this, the 2020–2022 NSMHW sample was linked to the ABS Person Level Integrated Data Asset (PLIDA) to source the PBS administrative data including Repatriation PBS (RPBS) data, with appropriate permissions. The PBS and RPBS administrative data was then used to create medications data items which were added to the 2020–2022 NSMHW dataset. 

The types of mental health-related medications sourced from PLIDA were:

• Antipsychotics
• Anxiolytics
• Hypnotics and sedatives
• Antidepressants
• Psychostimulants, agents used for ADHD and nootropics.

For more information on the PLIDA, refer to Person Level Integrated Data Asset.

The PBS is an Australian Government program that subsidises medications listed on the PBS Schedule for all Australian residents who hold a current Medicare card. In addition, some overseas visitors are eligible for some PBS medications through reciprocal health care agreements. The PBS subsidises medications for most medical conditions, and most PBS and RPBS subsidised prescriptions are dispensed by pharmacists and used by patients at home. Patients pay a 'co-payment' towards the cost of PBS subsidised medications, and many PBS medicines cost significantly more than the co-payment amount.

There are programs operating under Section 100 of the National Health Act 1953 particularly in remote and very remote areas, such as Aboriginal health services, which receive access to free and subsidised medicines, at times on a bulk supply basis, that are not captured through the PBS data when distributed to patients. These are unlikely to apply to respondents in the NSMHW, noting that the NSMHW sample design excludes very remote areas.

PBS subsidised prescriptions do not include over-the-counter medications, private prescriptions, dietary supplements, or medications supplied to most public hospital inpatients. Non-prescription medications and products are generally available in pharmacies, supermarkets, health food stores and other retailers and are typically used for mild health problems. There are also prescription medicines that are not listed on the PBS, referred to as non-PBS prescriptions. These medications, products and non-PBS prescriptions are not represented in the NSMHW-PBS linked data.

For further information on the PBS, refer to Pharmaceutical Benefits Scheme. 

The NSMHW-PBS linked data has been used to create data items for use with the 2020–2022 NSMHW dataset. These include:

• number of mental health-related medications dispensed in the last 12 months per NSMHW respondent
• number of mental health-related medications dispensed by type of mental health medication in the last 12 months per NSMHW respondent
• number of different types of mental health-related medication types dispensed in the last 12 months per NSMHW respondent

Data items created from the NSMHW-PBS linked data can be analysed with demographics, mental health disorders and use of health services collected from NSMHW respondents. A full list of the PBS mental health-related medications data items created for the NSMHW can be found in the Data Item List.

The PBS data in PLIDA includes the date of prescription and the date of supply. The timeframe used for analysis of PBS-NSMHW data in this release is based on date of supply, and spans from 12 months (365 days) before the individual respondent's NSMHW interview. This timeframe was chosen to align with the 12-month timeframe respondents were asked about in the NSMHW.

PLIDA linkage results have defined three (3) population groups for the NSMHW-PBS linked data. There are: NSMHW records that have been linked to PLIDA and have PBS data; NSMHW records that have been linked to PLIDA but do not have any PBS data (the ‘No PBS medications’ population); and NSMHW records that were unable to be linked to PLIDA (unknown PBS data). This last group accounts for approximately 7.9% of all 2020–2022 NSMHW respondents.

It should be noted that PBS data tells us when a subsidised mental health-related medication is prescribed and dispensed, but not whether the patients consumed the medication. It is also possible to have multiple prescriptions per medication type, and multiple medication types per person.

While the types of medications included in the NSMHW analyses are commonly prescribed for treating mental health conditions, they may also be prescribed to treat other conditions. A person's use of mental health-related medications does not imply a diagnosis of a mental health condition.

PBS medication types are classified using the 2023 Anatomical Therapeutic Chemical (ATC) classification system which is maintained by the World Health Organization (WHO) and widely used internationally.

Under the ATC, medications are classified into different groups based on the main active ingredient, the organ or system on which they act, and their therapeutic, pharmacological and chemical properties. Drugs are classified in a hierarchy with five different levels.

• The ATC first or main level has fourteen main anatomical or pharmacological groups comprising: Alimentary tract and metabolism; Blood and blood forming organs; Cardiovascular system; Dermatologicals; Genito urinary system and sex hormones; Systemic hormonal preparations, excluding sex hormones and insulins; Anti-infectives for systemic use; Antineoplastic and immunomodulating agents; Musculo-skeletal system; Nervous system; Antiparasitic products, insecticides and repellents; Respiratory system; Sensory organs; and Various
• The ATC second level divides each main group into either Pharmacological or Therapeutic subgroups
• The ATC third and fourth levels are Chemical, Pharmacological or Therapeutic subgroups
• The ATC fifth level is the chemical substance.

Mental health-related medications included in this data are classified under the N. Nervous system group and include selected ATC categories for N05: Psycholeptics and N06 Psychoanaleptics.

Psycholeptics are a group of drugs that tranquilise (central nervous system depressants). Drugs included from this group are:

• Antipsychotics (N05A) – drugs used to treat symptoms of psychosis (a severe mental disorder characterized by loss of contact with reality, delusions and hallucinations), common in conditions such as schizophrenia, mania and delusional disorder
• Anxiolytics (N05B) – drugs used to treat symptoms of anxiety
• Hypnotics and sedatives (N05C) – Hypnotic drugs are used to induce sleep and treat severe insomnia, and sedative drugs are used to reduce excitability or anxiety.

Psychoanaleptics are a group of drugs that stimulate the mood (central nervous system stimulants). Drugs included from this group are:

• Antidepressants (N06A) – drugs used to treat symptoms of clinical depression
• Psychostimulants and nootropics (N06B) – agents used for attention-deficit hyperactivity disorder and to improve impaired cognitive abilities (nootropics).¹

Mental health-related medications were classified down to the fourth ATC level. This is the lowest level of detail supported by the NSMHW-PBS data linkage. The count of mental health-related medication types has been defined as the total count of unique ATC codes at the fourth ATC level. The third level of the ATC has been used in the datacubes.

The Anatomical Therapeutic Chemical (ATC) classification version used in the PBS Schedule of Pharmaceutical Benefits can differ slightly from the World Health Organization (WHO) version. There are three differences between the 2023 WHO ATC classification and the PBS Schedule classification that impact interpretation of the PBS mental health-related medications data: 

• Prochlorperazine is regarded as an antiemetic (A04A) in the PBS Schedule while it is an antipsychotic (N05A) according to the WHO classification. This means that information on prochlorperazine will not appear in the data provided as it is not listed as a mental health drug in the PBS Schedule
• Bupropion is listed as an anti-smoking drug (N07B) in the PBS Schedule while it is an antidepressant (N06A) according to the WHO classification. This means that bupropion will not appear in the data as it is not listed as a mental health drug in the PBS schedule
• Lithium carbonate is classified as an antidepressant (N06A) in the PBS Schedule while it is an antipsychotic (N05A) according to the WHO classification. This means that lithium carbonate will appear in the data as an antidepressant rather than an antipsychotic.² 

For further information on the ATC, refer to WHOCC - Structure and principles.

For further information on the implementations of the ATC classification for PBS medications, refer to the PBS Body System. 

Introduction

Modelled estimates for Primary Health Networks (PHNs) and state/territory have been produced based on data from the 2020–2022 National Study of Mental Health and Wellbeing, 2021 Census of Population and Housing, the Estimated Resident Population (ERP) as at 30 June 2022, and aggregated administrative data. These include estimates of the number of people with 12-month mental disorders, as well as selected other mental health-related topics.

The modelled estimates can be interpreted as the expected value for a typical area in Australia with the same characteristics. For any particular modelled mental health characteristic (e.g. people with a 12-month mental disorder), there will be differences between the modelled estimate and the true number of people with that characteristic not accounted for in the measure of accuracy. One explanation for this is that significant local information about particular areas exists, but has not been included in the model, as it is not available to the ABS. It is important to consider local area knowledge when interpreting the modelled estimates for that region.

Used in conjunction with an understanding of local area characteristics and their reliability limitations, modelled estimates can assist in making decisions on issues such as the requirement for services.

Population groups

The modelled estimates are for persons aged 16–85 years who were usual residents of private dwellings, for all areas of Australia excluding Other Territories. This differs from the scope of the NSMHW, which also excluded Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities. Please refer to the ‘In scope population’ worksheet within each Data download file in the Mental health, Primary Health Networks - modelled estimates section of National Study of Mental Health and Wellbeing for further information about the population in scope of the NSMHW in each PHN and state/territory.

Geography

Modelled estimates have been produced at the PHN and state/territory level for all jurisdictions, excluding Other Territories.

The ABS Australian Statistical Geography Standard (ASGS), Edition 3 was used as the basis for combining data sources. State/territory boundaries for outputs are as defined within the main structure of ASGS. PHN regions are not defined or maintained within the ASGS. PHNs for outputs are an approximation of PHN regions, as defined by an ASGS Mesh Block to PHN allocation file provided by the Department of Health and Aged Care. The 2023 edition of PHN regions has been used.

Methodology

To produce accurate and detailed estimates of mental health topics at the PHN and state/territory level, models are created using detailed NSMHW data, in conjunction with Census data, administrative data, and ERP data to produce modelled estimates for those areas. The modelling method assumes that the relationships observed at the higher geographic level (as available from the NSMHW) between the characteristics of interest (e.g. whether a person has a 12-month mental disorder) and other known characteristics also hold at the smaller area level.

A mixed (or composite) estimate comprised of modelled and NSMHW survey data is then produced for each PHN and state/territory. A mixed (or composite) estimate gives results for each area that reflect the best trade-off between the accuracy of the direct survey data and the error associated with the modelled estimate.

Reliability of modelled estimates

The errors associated with the modelled estimates fall into four categories. Sampling error, non-sampling error, modelling error, and prediction error. The relative root mean squared error (RRMSE) provides an indication of the deviation of the modelled estimate from the true population value. The RRMSE is primarily a measure of prediction error, but in its calculation, it also inherits some aspects of modelling and sampling error.

Modelling assumes that the statistical relationships observed between explanatory characteristics and the characteristic of interest for the sampled population are not significantly different for populations not included in the survey. This is relevant for the modelled estimates presented in this publication, where the scope includes Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities that were not included in the NSMHW sample. Modelled relationships may be inadequate for describing the portion of a PHN’s population in Very Remote areas and discrete Aboriginal and Torres Strait Islander communities, and/or other parts of PHNs that don’t follow the typical associations between explanatory characteristics and the characteristic of interest.  The percentage of the population in each PHN and state/territory which is in scope of the NSMHW is provided in the ‘In scope population’ worksheet within each data download file. Users should consider these proportions when assessing the suitability of modelled estimates for their purposes.

Confidentiality

Modelled estimates have been confidentialised to ensure they meet ABS requirements for confidentiality.

Additional information

The sum of modelled estimates for PHNs may not align with the modelled estimates for states/territories because models for separate geographies are applied independently and some PHNs cross state/territory boundaries. Any differences between the sum of component modelled estimates and the equivalent published total modelled estimate will be small.

Users should note that modelled state/territory data will differ from direct survey estimates from the NSMHW. The NSMHW sample was designed to provide reliable national-level direct survey estimates and allowed for the production of limited direct survey estimates for states and territories. In addition to providing estimates for PHNs, modelling allows for more detailed disaggregations at the state/territory level (e.g. 10-year age groups by sex) than is possible directly from the NSMHW sample. Users should consider their particular data needs when using state/territory modelled or direct survey estimates.

Modelled estimates include total 'Population' counts for each PHN and state/territory, created for the production and analysis of PHN and state/territory data; these are not official ABS population statistics.

Detailed explanatory notes are available for the modelled estimates. These can be obtained on request from mental.health.statistics@abs.gov.au.

There are a number of other surveys in Australia, existing or currently in development, that focus on mental health that may be of interest to readers.

Information on psychotic illness such as schizophrenia was collected in the 2010 Survey of High Impact Psychosis. For more information see People living with psychotic illness 2010.

The Australian Government has allocated funding to the Department of Health and Aged Care to conduct a child and adolescent mental health and wellbeing study.

The study will measure mental health of Australian children and adolescents, as recommended in the National Children’s Mental Health and Wellbeing Strategy. It will be designed with child and adolescent mental health experts, with study design commencing in 2023-2024. The aims and scope of the study are yet to be decided.

The previous Australian Child and Adolescent Survey of Mental Health and Wellbeing (Young Minds Matter) was funded by the Australian Government Department of Health and Aged Care and conducted by the University of Western Australia through the Telethon Kids Institute in 2014. For more information see Young Minds Matter.

The Queensland Urban Indigenous Mental Health Survey (QUIMHS), also known as the Staying Deadly Survey, was conducted in 2022 by the QUIMHS Research Team based at the Queensland Centre for Mental Health Research (QCMHR) in collaboration with the Institute for Urban Indigenous Health.

The survey aimed to learn more about the mental health and mental health needs of Aboriginal and Torres Strait Islander adults in Southeast Queensland.

For more information see The Staying Deadly Survey: The Queensland Urban Indigenous Mental Health Survey Report.

The Government has allocated funding to the Department of Health and Aged Care for a national study to measure the mental health of First Nations people. The aims and scope of the study are yet to be decided but will be developed in partnership with First Nations peoples, to ensure it is culturally appropriate and meets the needs of communities.

1. Australian Institute of Health and Welfare, 'Data tables: Mental health-related prescriptions', accessed 20 March 2024.
2. Australian Institute of Health and Welfare, 'Mental health-related prescriptions', accessed 19 March 2024.