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# National Study of Mental Health and Wellbeing methodology

Reference period
2020-21
Released
22/07/2022
Next release Unknown

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.

The 2020-21 cohort is the first of two for the study. 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 started in December 2021 and will finish in late 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 a mental illness?
• 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.

### Support services

Some of this information may cause distress. The following support services are available 24-hours, 7 days:

Lifeline: 13 11 14

Suicide Call Back Service: 1300 659 467

Beyond Blue: 1300 224 636

MensLine Australia: 1300 789 978

Kids Helpline: 1800 551 800

For further information see Mental health resources

## How the data is collected

### Scope

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 health disorders in the Australian population.

### Sample design

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.

### Response rates

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

NumberPer cent
Fully respondingTotal5,55457.1
Non-responseRefusal9459.7
Non-response1,47315.1
Part response1,76218.1
Total4,18042.9
Total 9,734100

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.

### Collection method

The study was collected over an 8-month period from 5th December 2020 to 31st July 2021.  Households were required to complete the study 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.

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 to 85 years. The random selection was automatically performed upon completion of the Household Form.

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

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.

### Content

The study collected the following content:

• Demographics including age, sex, 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 health including depression, mania, panic, social phobia, agoraphobia, generalised anxiety, substance use, obsessive-compulsive disorder, post-traumatic stress disorder
• Suicidality
• Self-harm
• Disordered eating
• Use of health and social support services

The 2020-21 cohort 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. Data by Gender are available through the study microdata product or customised data requests. The sample achieved for 2020-21 is insufficient to produce reliable estimates of the prevalence of mental disorders for all items within the Standard. Table 4 in Data downloads presents estimates of mental disorders by sexual orientation. ABS will produce a combined sample from both cohorts of the study (2020-21 and 2021-22) which may allow for further disaggregation of items within the Standard by mental health status and other topics within the study.

See the Data Item List for full details of content collected for the 2020-21 NSMHW.

## Comparison between 2020-21 and 2007

The ABS previously conducted this survey in 2007. The 2020-21 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 2020-21 and 2007.

Many of the non-diagnostic topics and the order in which they were collected in 2020-21 differs from that in 2007. Some topics collected in 2007 were removed and new topics were added. Other topics changed significantly between 2020-21 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 2020-21 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 2020-21, the comorbidity of mental health disorders and physical health conditions is not comparable with 2007.

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 2020-21 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 2020-21 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 2020-21 did not include the two-week persistence as a condition for meeting 12-month diagnosis. 12-month diagnosis in 2020-2021 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 2020-21 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 2020-21 and 2007.

## How the data is processed

### Coding

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 health 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.

### Estimation methods

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 were calibrated to the estimated resident population (ERP) at March 2021. The Australian population 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).

Analysis showed that the standard weighting approach did not adequately compensate for undercoverage in the 2021 SHWB sample 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 July 2021) for labour force status, educational attainment, and household composition. 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, at 31 March 2021.

Sample counts and weighted estimates are presented in the table below.

Sample counts and weighted estimates, Australia
Persons in sampleWeighted estimate
Age group (years)Males (no.)Females (no.)Persons (no.)Males ('000)Females ('000)Persons ('000)
16 - 242502955451,376.41,314.72,691.1
25 - 343894518401,822.91,865.63,688.5
35 - 444264819071,696.11,726.23,422.4
45 - 543914047951,547.81,640.33,188.1
55 - 643964968921,419.11,514.32,933.4
65 - 744735551,0281,148.11,240.32,388.3
75 - 85237310547643.26891,332.2
Total persons aged 16-85 years2,5622,9925,5549,653.509,990.5019,644.00

### Accuracy

#### Reliability of estimates

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

• non-sampling error
• sampling error.

### Non-sampling error

Non-sampling error is caused by factors other than those related to sample selection. It is any factor that results in the data values not accurately reflecting the true value of the population.

It can occur at any stage throughout the survey process. Examples include:

• selected people who do not respond (e.g., refusals, non-contact)
• questions being misunderstood
• responses being incorrectly recorded
• errors in coding or processing the survey data.

### Sampling error

Sampling error is the expected difference that can occur between the published estimates and the value that would have been produced if the entire population had been surveyed. Sampling error is the result of random variation and can be estimated using measures of variance in the data.

### Standard error

One measure of sampling error is the standard error (SE). There are about two chances in three that an estimate will differ by less than one SE from the figure that would have been obtained if the entire population had been included. There are about 19 chances in 20 that an estimate will differ by less than two SEs.

### Relative standard error

The relative standard error (RSE) is a useful measure of sampling error. It is the SE expressed as a percentage of the estimate:

$$R S E \%=\left(\frac{S E}{e s t i m a t e}\right) \times 100$$

Only estimates with RSEs less than 25% are considered reliable for most purposes. Estimates with larger RSEs, between 25% and less than 50%, have been included in the publication, but are flagged to indicate they are subject to high SEs. These should be used with caution. Estimates with RSEs of 50% or more have also been flagged and are considered unreliable for most purposes. RSEs for these estimates are not published.

### Margin of error for proportions

Another measure of sampling error is the Margin of Error (MOE). This describes the distance from the population value that the sample estimate is likely to be within and is particularly useful to understand the accuracy of proportion estimates. It is specified at a given level of confidence. Confidence levels typically used are 90%, 95% and 99%.

For example, at the 95% confidence level, the MOE indicates that there are about 19 chances in 20 that the estimate will differ by less than the specified MOE from the population value (the figure obtained if the whole population had been enumerated). The 95% MOE is calculated as 1.96 multiplied by the SE:

$$\operatorname{MOE}={SE}\times1.96$$

The RSE can also be used to directly calculate a 95% MOE by:

$$\operatorname{MOE}(y) \approx \frac{R S E(y) \times y}{100} \times 1.96$$

The MOEs in this publication are calculated at the 95% confidence level. This can easily be converted to a 90% confidence level by multiplying the MOE by:

$$\frac{1.615} {1.96}$$

or to a 99% confidence level by multiplying the MOE by:

$$\frac{2.576} {1.96}$$

Depending on how the estimate is to be used, an MOE of greater than 10% may be considered too large to inform decisions. For example, a proportion of 15% with an MOE of plus or minus 11% would mean the estimate could be anything from 4% to 26%. It is important to consider this range when using the estimates to make assertions about the population.

### Confidence intervals

A confidence interval expresses the sampling error as a range in which the population value is expected to lie at a given level of confidence. A confidence interval is calculated by taking the estimate plus or minus the MOE of that estimate. In other terms, the 95% confidence interval is the estimate +/- MOE.

### Calculating measures of error

Proportions or percentages formed from the ratio of two estimates are also subject to sampling errors. The size of the error depends on the accuracy of both the numerator and the denominator. A formula to approximate the RSE of a proportion is given below. This formula is only valid when the numerator (x) is a subset of the denominator (y):

$$\operatorname{RSE}\left(\frac{x}{y}\right) \approx \sqrt{[R S E(x)]^{2}-[R S E(y)]^{2}}$$

When calculating measures of error, it may be useful to convert RSE or MOE to SE. This allows the use of standard formulas involving the SE. The SE can be obtained from RSE or MOE using the following formulas:

$$S E=\frac{R S E\%\times estimate} {100}$$

$$S E=\frac{MOE}{1.96}$$

### Comparison of estimates

The difference between two survey estimates (counts or percentages) can also be calculated from published estimates. Such an estimate is also subject to sampling error. The sampling error of the difference between two estimates depends on their SEs and the relationship (correlation) between them. An approximate SE of the difference between two estimates (x - y) may be calculated by the following formula:

$$S E(x-y) \approx \sqrt{[S E(x)]^{2}+[S E(y)]^{2}}$$

While this formula will only be exact for differences between unrelated characteristics or sub-populations, it provides a reasonable approximation for the differences likely to be of interest in this publication.

### Significance testing

When comparing estimates between surveys or between populations within a survey, it is useful to determine whether apparent differences are 'real' differences or simply the product of differences between the survey samples.

One way to examine this is to determine whether the difference between the estimates is statistically significant. This is done by calculating the standard error of the difference between two estimates (x and y) and using that to calculate the test statistic using the formula below:

$$\left(\frac{|x-y|}{S E(x-y)}\right)$$

where

$$S E(y)\approx\frac{R S E(y) \times y}{100}$$

If the value of the statistic is greater than 1.96, we can say there is good evidence of a statistically significant difference at 95% confidence levels between the two populations with respect to that characteristic. Otherwise, it cannot be stated with confidence that there is a real difference between the populations.

## How the data is released

### Release strategy

The 2020-21 NSMHW release presents national estimates. The sample of 5,554 fully responding households is insufficient for detailed analysis of state and territory estimates.

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.

### Confidentiality

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 introduction of perturbation in publications ensures that these statistics are consistent with statistics released via services such as TableBuilder.

## Mental health disorders

### World Health Organisation World Mental Health-Composite International Diagnostic Interview (WHO WMH-CIDI) 3.0

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.

### Hierarchy rules

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.

12-month mental disorders, comparison of ICD-10 and DSM-IV diagnostic criteria with and without hierarchy rules applied(a)
ICD-10 with hierarchyICD-10 without hierarchyDSM-IV with hierarchyDSM-IV without hierarchy
Persons aged 16-85 years (‘000)
Anxiety disordersPanic Disorder720.3720.3503.0503.0
Agoraphobia909.3909.3326.3326.3
Social Phobia1,379.21,379.21,467.61,467.6
Generalised Anxiety Disorder744.3833.7666.9876.1
Obsessive-Compulsive Disorder624.5624.5838.3838.3
Post-Traumatic Stress Disorder1,110.31,110.3846.8846.8
Total Anxiety Disorders3,299.23,299.23,078.83,129.0
Affective disordersDepressive Episode(b)(c)890.41,124.01,169.71,415.3
Dysthymia330.6476.9309.5434.7
Bipolar Affective Disorder(d)417.8417.8198.1198.1
Total Affective Disorders1,458.01,471.91,394.91,473.3
Substance Use disordersAlcohol Harmful Use/Abuse309.0419.2279.4390.8
Alcohol Dependence183.2183.2170.4170.4
Drug Use Disorders(e)190.2190.2189.3189.3
Total Substance Use Disorders658.5658.5615.3615.3
Any 12-month mental disorder(f)4,198.74,201.14,000.64,010.3
No 12-month mental disorder(g)15,445.315,442.915,643.415,633.8
Total persons aged 16-85 years19,644.019,644.019,644.019,644.0

a. Persons who met criteria for diagnosis of a lifetime mental disorder and had sufficient symptoms of that disorder in the 12 months prior to interview.
b. ICD-10 diagnosis includes Severe/Moderate/Mild Depressive Episode.
c. DSM-IV diagnosis includes Major Depressive Episode and Major/Minor Depressive Disorder.
d. DSM-IV diagnosis includes Bipolar I and Bipolar II Disorders.
e. Includes Harmful Use/Abuse and Dependence.
f. A person may have had more than one 12-month mental disorder. The components when added may therefore not add to the total shown.
g. Persons who did not meet criteria for diagnosis of a lifetime mental disorder and those who met criteria for diagnosis of a lifetime mental disorder but did not have symptoms in the 12 months prior to interview.

### World Health Organisation International Classification of Diseases, Tenth Revision (ICD-10)

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
• Obsessive-Compulsive Disorder (OCD)
• Post-Traumatic Stress Disorder (PTSD).

### Panic disorder

A panic attack is a discrete episode of intense fear or discomfort that starts abruptly and peaks within a few minutes. Panic attacks last at least some minutes but typically less than half an hour. At least four symptoms must be present from the list below, one of which must be from the first four:

• pounding heart
• sweating
• trembling or shaking
• dry mouth
• difficulty breathing
• feeling of choking
• chest pain or discomfort
• nausea or abdominal distress
• feelings of unreality or depersonalisation
• fear of passing out or losing control
• fear of dying
• hot flushes or cold chills
• numbness or tingling sensations.

The essential feature of Panic Disorder is recurrent attacks of severe anxiety (panic), which are not restricted to any particular situation or set of circumstances (i.e., do not occur in the presence of a phobia, or in situations of danger) and are therefore unpredictable.

### Agoraphobia

Characterised by marked and consistently manifest fear in, or avoidance of, at least two of the following situations:

• crowds
• public places (i.e., using public transport; standing in a line in a public place; being in a department store, shopping centre, or supermarket; being in a movie theatre auditorium, lecture hall, or church; being in a restaurant or any other public place)
• travelling alone (i.e., travelling alone or being alone away from home)
• travelling away from home.

At least two of the following anxiety symptoms must have been present together with the feared situation and one of these symptoms must be from the first four listed:

• pounding heart
• sweating
• trembling or shaking
• dry mouth
• difficulty breathing
• feeling of choking
• chest pain or discomfort
• nausea or abdominal distress
• feelings of unreality or depersonalisation
• fear of passing out, or losing control
• fear of dying
• hot flushes or cold chills
• numbness or tingling sensations.

The person also experiences significant emotional distress due to the avoidance or the anxiety symptoms and recognises that these are excessive or unreasonable.

### Social Phobia

Characterised by fear and/or avoidance of one or more social or performance situations such as:

• meeting new people
• talking to people in authority
• speaking up in a meeting or class
• going to social gatherings
• performing in front of an audience
• taking an important exam
• working while someone watches
• entering a room when others are present
• talking with people they do not know very well
• disagreeing with people
• writing, eating, or drinking while someone watches
• using a public bathroom
• dating
• social or performance situation.

The presence of Social Phobia is also characterised by:

• The fear of being the focus of attention or of behaving in a way that will be embarrassing or humiliating; or the avoidance of either being the focus of attention, or of situations where there is fear of behaving in an embarrassing or humiliating way
• At least two anxiety symptoms (from the list in Agoraphobia above) must be present in the feared situation at some time since the onset of the disorder, together with at least one of the following: blushing or shaking; nausea or fear of vomiting; or the urgency or fear of losing control of bowels or bladder
• Significant distress caused by the symptoms or by the avoidance, and the person recognises that these are excessive or unreasonable.

### Generalised Anxiety Disorder

Characterised by a period of at least six months with tension, worry and apprehension about everyday events and problems. The disorder is not due to a physical disorder or substance use. At least four of the following symptoms must be present, with at least one of the first four:

• pounding heart
• sweating
• trembling or shaking
• dry mouth
• difficulty breathing
• feeling of choking
• chest pain
• nausea, stomach pain or discomfort
• dizziness
• feelings of unreality or depersonalisation
• fear of losing control or passing out
• fear of dying
• hot flushes or cold chills
• numbness or tingling sensations
• muscle tension or aches and pains
• restlessness
• feeling on edge
• a sensation of a lump in the throat
• exaggerated response to minor surprises
• difficulty concentrating
• irritability
• trouble in getting to sleep because of worry.

Hierarchy rules have been applied to Generalised Anxiety Disorder. To meet criteria for the 'with hierarchy' version:

• the Generalised Anxiety Disorder does not occur exclusively within the duration of Panic Disorder
• the Generalised Anxiety Disorder is not exclusively associated with social and performance situations (i.e., Social Phobia)
• the Generalised Anxiety Disorder does not occur exclusively within the duration of (and is not exclusively associated with) obsessions and compulsions (i.e., Obsessive-Compulsive Disorder).

The original exclusion rules from the ICD-10 also consider the presence of other phobic disorders and hypochondriacal disorder. As the 2020-21 study did not collect information for Specific Phobia or Hypochondriacal Disorder, the Generalised Anxiety Disorder prevalence may include some people with these disorders.

### Obsessive-Compulsive Disorder

Either obsessions or compulsions (or both) are present on most days for at least two weeks. Obsessions (thoughts, ideas, or images) and compulsions (acts) share the following features, all of which must be present:

• repetitive and unpleasant, and at least one obsession or compulsion is acknowledged as excessive or unreasonable
• the person tries to resist them, and at least one obsession or compulsion that is unsuccessfully resisted must be present
• the person derives no pleasure from the obsessive thought or compulsive act
• the obsessions or compulsions cause distress or interfere with the person's social or individual functioning
• the respondent considers that the obsessions and compulsions do not occur exclusively within episodes of depression (i.e., this is based on self report by the respondent, not according to diagnosis made by the WMH-CIDI 3.0).

### Post-Traumatic Stress Disorder

Characterised by symptoms experienced within six months of exposure to a traumatic event which would be likely to cause pervasive distress in almost anyone. To be assessed for this disorder, the respondent had to have reported experiencing at least one of the following traumatic events:

• direct combat experience in a war
• a war or ongoing terror as a peacekeeper
• a war as an unarmed civilian
• living in a place with ongoing terror
• ever being a refugee
• being kidnapped or held captive
• being exposed to a toxic substance
• a life-threatening car accident
• a life-threatening accident
• a bushfire, flood, or other natural disaster
• a man-made disaster or bomb explosion
• a life-threatening illness
• being beaten as a child
• being beaten by a spouse or partner
• being beaten by anyone else
• being mugged, held up or threatened with a weapon
• rape
• sexual molestation
• being stalked
• an unexpected death at a young age of someone very close
• a child with a life-threatening illness or injury
• traumatic experience (e.g., kidnap, torture, or rape) of someone very close
• witness serious physical fights at home as a child
• someone being badly injured or killed, or unexpectedly seeing a dead body
• doing something that accidentally led to serious injury or death of another person
• seriously injuring, torturing, or killing another person on purpose
• witnessing atrocities
• any other extremely traumatic or life-threatening events
• any other extremely traumatic or life-threatening events including events the respondent does not wish to describe.

The respondent was asked to determine which event was their worst traumatic event. To meet the criteria for this disorder, the person must report all the following reactions to their worst traumatic event:

• The traumatic event is persistently remembered or relived (e.g., flashbacks, dreams, or distress when reminded of the event), or the person experiences distress when exposed to circumstances resembling or associated with the event
• The person exhibits an actual or preferred avoidance of circumstances resembling or associated with the event, which was not present before that event
• The person exhibits either an inability to recall some or all aspects of the trauma or two or more symptoms of increased sensitivity and arousal (difficulty in falling or staying asleep; irritability; difficulty concentrating; hypervigilance; exaggerated startle response).

#### 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).

### Hypomania

Hypomania is characterised by elevated or irritable mood to a degree that is abnormal for the individual concerned and sustained for at least four consecutive days. It leads to some interference with daily living but to a lesser degree than Mania. At least three of the following symptoms must be present:

• increased activity or restlessness
• increased talkativeness
• distractibility
• decreased need for sleep
• increased sexual energy
• overspending or other types of reckless or irresponsible behaviour
• over-familiarity or increased sociability.

Hierarchy rules have been applied to Hypomania. To meet criteria for the 'with hierarchy' version, the person cannot have met criteria for an episode of Mania in their lifetime. If they do meet criteria for Mania, the duration of Mania and Hypomania cannot overlap (Mania onset must be after Hypomania recency or Hypomania onset must be after Mania recency), or the longest Hypomanic episode must have been longer than the Manic episode.

The original exclusion rules from the ICD-10 also consider the presence of any Depressive Episodes, Cyclothymia and Anorexia Nervosa. As the 2020-21 study did not collect information for Cyclothymia or Anorexia Nervosa (and the presence of Depressive Episodes was not operationalised by the diagnostic algorithm), Hypomania may include some people with these disorders.

### Mania

Mood is elevated, expansive or irritable and abnormal for the person concerned. The episode lasts for at least seven days (unless the episode is severe enough to require hospitalisation), causes severe interference with personal functioning, is not directly caused by substance use or a physical condition, and is characterised by at least three of the following (four if the mood is merely irritable):

• increased activity or restlessness
• increased talkativeness
• flight of ideas or the feeling that thoughts are racing
• loss of normal social inhibitions
• decreased need for sleep
• inflated self-esteem or grandiosity
• distractibility
• reckless behaviour
• marked sexual energy or sexual indiscretions.

### Depressive Episode

Depressive Episode lasts for at least two weeks and is characterised by the presence of a number of the following symptoms:

• depressed mood
• loss of interest in activities
• lack of energy or increased fatigue
• loss of confidence or self esteem
• feelings of self-reproach or excessive guilt
• thoughts of death or suicide, or suicide attempts
• diminished ability to concentrate, think or make decisions
• change in psychomotor activity (agitation or retardation)
• sleep disturbance
• change in appetite.

The study collected information to differentiate between three different types of Depressive Episode, based on the number of symptoms the person experienced:

• Severe Depressive Episode – the first three symptoms from the above list and additional symptoms from the remainder of the list to give a total of at least eight
• Moderate Depressive Episode - at least two of the first three symptoms from the above list and additional symptoms from the remainder of the list to give a total of at least six
• Mild Depressive Episode - at least two of the first three symptoms from the above list and additional symptoms from the remainder of the list to give a total of at least four.

Hierarchy rules have been applied to each of the Depressive Episodes. To meet criteria for the 'with hierarchy' versions, the person cannot have met criteria for either Hypomanic or Manic episodes in their lifetime.

The three types of Depressive Episode collected by the 2020-21 study are also mutually exclusive. A person cannot be diagnosed with Moderate Depressive Episode if the criteria for a Severe Depressive Episode have already been met and a diagnosis of a Mild Depressive Episode is considered only when the other two types of depression have been excluded. This criterion is applied regardless of whether the 'with hierarchy' or 'without hierarchy' versions of the disorder is used.

### Dysthymia

A disorder characterised by at least two years of constant (or constantly recurring) chronic depressed mood, where intervening periods of normal mood rarely last for longer than a few weeks.

During some of the periods of depression at least three of the following are present:

• reduced energy or activity
• insomnia
• loss of self-confidence or feeling inadequate
• difficulty in concentrating
• frequent tearfulness
• loss of interest in or enjoyment of sex and other pleasurable activities
• feeling of hopelessness or despair
• feeling unable to cope with everyday responsibilities
• pessimism about the future or brooding over the past
• social withdrawal
• reduced talkativeness.

Hierarchy rules have been applied to Dysthymia. To meet criteria for the 'with hierarchy' version:

• the person must not have met criteria for either Hypomanic or Manic episodes in their lifetime
• there must be no episodes of Severe or Moderate Depression identified within the first two years of Dysthymia.

### Bipolar Affective Disorder

Characterised by episodes of Mania and/or Hypomania either alone or in conjunction with Depressive Episodes. For the 2020-21 study, a diagnosis of Bipolar Affective Disorder was given if the person met criteria for Mania or Hypomania and had experienced one episode of mood disturbance (Mania, Hypomania or Depression). The study does not allow differentiation according to the type of the current episode.

#### 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.

### Alcohol Harmful use

There is clear evidence that the use of alcohol was responsible for (or substantially contributed to) physical or psychological harm, including impaired judgement or dysfunctional behaviour which may lead to disability or have adverse consequences for interpersonal relationships.

The nature of the harm should be clearly identifiable by including at least one of the following:

• frequent interference with work or other responsibilities
• causing arguments or other serious problems with family, friends, neighbours, or co-workers
• jeopardising safety because of alcohol use
• being arrested or stopped by police for drunk driving or drunk behaviour.

Hierarchy rules have been applied to Alcohol Harmful Use. To meet criteria for the 'with hierarchy' version, a person cannot have met a diagnosis of Alcohol Dependence during the same time period (i.e., the duration of the two disorders must not overlap).

### Alcohol Dependence Syndrome

A maladaptive pattern of behaviour in which the use of alcohol takes on a much higher priority for a person than other behaviours that once had greater value. The central characteristic is the strong, sometimes overpowering, desire to consume alcohol despite significant alcohol-related problems. A diagnosis was achieved if three or more of the following occurred within the same year:

• strong desire or compulsion to consume alcohol
• difficulties in controlling alcohol consumption behaviour
• withdrawal symptoms (e.g., fatigue, headaches, diarrhea, the shakes, or emotional problems)
• tolerance to alcohol (e.g., needing to drink a larger amount for the same effect)
• neglect of alternative interests because of alcohol use
• continued use despite knowing it is causing significant problems.
##### 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).

### Other Substance Harmful Use

The study collected information on:

• Harmful Use - opioids
• Harmful Use - cannabinoids
• Harmful Use - sedatives
• Harmful Use – stimulants.

There is clear evidence that the use of opioids/cannabinoids/sedatives/stimulants were responsible for (or substantially contributed to) physical or psychological harm, including impaired judgement or dysfunctional behaviour which may lead to disability or have adverse consequences for interpersonal relationships.

The nature of the harm should be clearly identifiable by including at least one of the following:

• frequent interference with work or other responsibilities
• causing arguments or other serious problems with family, friends, neighbours, or co-workers
• jeopardising safety because of substance use
• being arrested or stopped by police for driving while intoxicated or other behaviour while intoxicated.

Hierarchy rules have been applied to Other Substance Harmful Use. To meet criteria for the 'with hierarchy' versions, a person cannot have met a diagnosis of Dependence on the same substance during the same time period (i.e., the duration of the two disorders must not overlap).

### Other Substance Dependence Syndrome

The study collected information on:

• Dependence Syndrome - opioids
• Dependence Syndrome - cannabinoids
• Dependence Syndrome - sedatives
• Dependence Syndrome - stimulants.

Opioids/cannabinoids/sedatives/stimulants Dependence Syndrome is a maladaptive pattern of substance use in which the use of the substance takes on a much higher priority for a person than other behaviours that once had greater value. The central characteristic is the strong, sometimes overpowering, desire to take the substance despite significant substance-related problems. Diagnoses were achieved if three or more of the following occurred in the 12 months prior to interview:

• strong desire or compulsion to take the substance
• difficulties in controlling substance-taking behaviour
• withdrawal symptoms (e.g., fatigue, headaches, diarrhoea, the shakes, or emotional problems)
• tolerance to the drug (e.g., needing to use a larger amount for the same effect)
• neglect of alternative interests because of substance use
• continued use despite knowing it is causing significant problems.

### Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)

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 study. 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
• Obsessive-Compulsive Disorder (OCD)
• Post-Traumatic Stress Disorder (PTSD).

### Panic Disorder

The essential feature of this disorder is recurrent panic (anxiety) attacks that occur suddenly and unpredictably. At least one of the attacks has been followed by one month or more of at least one of the following:

• worry that the attack means that the person is 'going crazy', losing control or having a heart attack
• change in behaviour because of the attacks.

#### Panic Disorder with/without Agoraphobia

A person may have met criteria for Panic Disorder with or without the presence of Agoraphobia.

#### Panic Attack

A period of intense fear or discomfort which begins suddenly and reaches a peak within ten minutes. At least four of the following symptoms are present:

• pounding heart
• sweating
• trembling or shaking
• shortness of breath
• feeling of choking
• chest pain
• nausea
• dizziness
• feelings of unreality
• fear of losing control
• fear of dying
• numbness or tingling sensations
• hot flushes or cold chills.

### Agoraphobia

The disorder is characterised by anxiety about being in situations from which escape might be difficult (or embarrassing) or in which help may not be available if the person has a panic attack. Such situations include:

• being outside the home alone
• being in a crowd
• travelling in trains, buses, or cars
• being in a public place.

The person avoids the situations, endures them with distress or requires the presence of a companion.

#### Agoraphobia without Panic Disorder

The symptoms of Agoraphobia relate to a fear of developing panic-like symptoms, but the person has never met the criteria for Panic Disorder.

### Social Phobia

The disorder is characterised by a marked and persistent fear of one or more social or performance situations in which a person is exposed to unfamiliar people or to possible scrutiny by others. The person fears that they will act in a way (or show anxiety symptoms) that will be embarrassing or humiliating. Exposure to the feared situation almost always provokes anxiety which may take the form of a panic attack. The feared situations are avoided or endured with distress and the person recognises that the fear is excessive or unreasonable. The disorder is accompanied by clinically significant distress and interference with normal routine and functioning.

The duration of the symptoms must have been at least six months for people who were aged less than 18 years when the symptoms last occurred. The duration of the symptoms must have been more than one year or people who were aged at least 18 years when the symptoms last occurred.

The disorder is characterised by excessive anxiety and worry about a number of events or activities, occurring more days than not for at least six months. Three or more of the following symptoms are present (with at least some present for more days than not for the six months prior to interview):

• restlessness
• fatigue
• difficulty concentrating
• irritability
• muscle tension
• sleep disturbance.

The person finds it difficult to control the worry, and it causes clinically significant distress or impairment in social, occupational, or other key areas of functioning.

A person is excluded from diagnosis if the GAD is associated with one or more of the following self-reported conditions:

• mental health
• substance use
• social phobias
• agoraphobia
• specific phobias
• obsessions
• compulsions
• being away from home or apart from loved ones.

Hierarchy rules have been applied to GAD. To meet criteria for the 'with hierarchy' version, the symptoms/disturbance cannot have occurred exclusively during a mood disorder (Major or Minor Depressive Disorder, Dysthymia or Mania).

### Obsessive-Compulsive Disorder (OCD)

The disorder is characterised by obsessions, compulsions, or a combination of both.

Obsessions are defined by the following:

• recurrent and persistent thoughts, impulses, or images that are experienced as intrusive and inappropriate and that cause marked anxiety
• the thoughts, impulses or images are not simply excessive worries about real-life problems
• the person tries to ignore or suppress such thoughts, impulses, or images or to neutralise them with some thought or action
• the person realises that the thoughts, impulses, or images come from his or her own mind and are not imposed from without.

Compulsions are defined by the following:

• repetitive behaviours or mental acts that the person feels driven to perform in response to an obsession
• the behaviours or mental acts are aimed at preventing or reducing distress or some dreaded event or situation but are not realistic or are clearly excessive.

The disorder is also characterised by the obsessions or compulsions causing marked distress, being time consuming, or significantly interfering with the person's normal routine or functioning.

Additionally, the person realises that the obsessions or compulsions are excessive or unreasonable.

The obsessions or compulsions cannot occur exclusively within episodes of depression. In this case, depression was based on the endorsement of questions about being sad or depressed when the symptoms of OCD occurred. Therefore, depression was self-reported and not verified medically or through a WMH-CIDI 3.0 diagnosis.

### Post-Traumatic Stress Disorder (PTSD)

The disorder is characterised by symptoms lasting more than one month following exposure to a traumatic event in which the person experienced or witnessed an event that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others.

The person's response to the event involved intense fear, helplessness, or horror. The traumatic event is persistently re-experienced in one or more of the following ways:

• recollections
• dreams
• acting or feeling as if the event were recurring
• distress when reminded of the event
• physiological reactivity when reminded of the event.

In addition, the person exhibits avoidance of things associated with the event evidenced by three or more of the following:

• efforts to avoid thinking, feeling, or talking about the event
• efforts to avoid activities, places or people that arouse recollections of the event
• inability to recall aspects of the trauma
• diminished interest or participation in significant events
• feelings of estrangement from others
• restricted range of affect (e.g., unable to have loving feelings)
• sense of a foreshortened future.

Further, two or more of the following symptoms of increased arousal are present:

• difficulty falling or staying asleep
• irritability
• difficulty concentrating
• hypervigilance
• exaggerated startle response.

The disturbance causes clinically significant distress or impairment in social, occupational, and other important areas of functioning.

#### 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).

### Major Depressive Episode

This disorder is characterised by the presence of five or more symptoms during the same two-week period, with at least one of the symptoms from the first two on the list:

• depressed mood
• loss of interest and pleasure
• weight change or appetite disturbance
• sleep disturbance
• psychomotor changes
• low energy
• feelings of worthlessness or guilt
• poor concentration or difficulty making decisions
• recurrent thoughts of death or suicidal ideation, plans or attempts.

These symptoms must represent a change from previous functioning and are not better accounted for by bereavement. If the depressive episode is associated with bereavement, then the episode must be longer than two months duration. In addition, the episode must be accompanied by clinically significant distress or impairment in social, occupational, or other key areas of functioning.

### Major and Minor Depressive Disorders

To be diagnosed with Major Depressive Disorder a person must have met criteria for a single Major Depressive Episode. Hierarchy rules have been applied to Major Depressive Disorder. For the 'with hierarchy' version, a diagnosis can only be made if a person has never met criteria for a Hypomanic or Manic Episode.

Minor Depressive Disorder is diagnosed if a person has at least two (but less than five) symptoms of a Major Depressive Episode. Hierarchy rules have been applied to Minor Depressive Disorder. For the 'with hierarchy' version, a diagnosis can only be made if a person has never:

• met criteria for Major Depressive Episode and Dysthymia; and
• experienced a Hypomanic or Manic Episode.

### Recurrent Brief Depression

This disorder is characterised by the presence of symptoms lasting at least two days, but less than two weeks. The symptoms occur at least once a month for 12 consecutive months and are not associated with the menstrual cycle. The symptoms cause significant distress or impairment in social, occupational, or other areas of functioning. At least five of the following symptoms must be present and at least one of the symptoms should be from the first two on the list:

• depressed mood
• loss of interest or pleasure
• significant weight loss when not dieting or weight gain, or decrease or increase in appetite
• insomnia or hypersomnia
• psychomotor agitation or retardation
• fatigue or loss of energy
• feelings of worthlessness or excessive or inappropriate guilt (which may be delusional)
• diminished ability to think or concentrate, or indecisiveness
• recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific suicide plan.

The symptoms are not better accounted for by bereavement, or if the symptoms are associated with bereavement, they have persisted for longer than two months.

Hierarchy rules have been applied to Recurrent Brief Depression. For the 'with hierarchy' version, a diagnosis can only be made if a person has never had a Depressive Episode and met criteria for Dysthymic Disorder; and had a Manic Episode, Mixed Episode or Hypomanic Episode and met criteria for Cyclothymic Disorder.

As the 2020-21 study did not collect information on Mixed Episode or Cyclothymic Disorder, Recurrent Brief Depression may include some people with these disorders.

### Dysthymic Disorder

The disorder is characterised by a chronically depressed mood, which occurs for most of the day and on more days than not, for at least two years. There cannot have been a break of two months or more. Additionally, at least two of the following symptoms are present:

• appetite disturbance
• sleep disturbance
• low energy
• low self-esteem
• poor concentration or difficulty making decisions
• feelings of hopelessness.

The episode must be accompanied by significant clinical distress or impairment in social, occupational, or other key areas of functioning.

Hierarchy rules have been applied to Dysthymia. For the 'with hierarchy' version, a diagnosis can only be made if the initial two-year period of symptoms is free of Major Depressive Episodes and the person has never had a Hypomanic or Manic episode.

### Hypomanic Episode

An episode is characterised by an abnormally elevated, expansive, or irritable mood lasting at least four days. Three or more of the following symptoms (four if the mood is only irritable) are present:

• inflated self-esteem or grandiosity
• decreased need for sleep
• increased talkativeness
• flight of ideas or the feeling that thoughts are racing
• distractibility
• increase in goal-directed activity or psychomotor agitation
• excessive involvement in pleasurable activities that have a high potential for painful consequences.

While the episode is associated with an unequivocal change in functioning, that is uncharacteristic of the person when not symptomatic, it is not severe enough to cause marked impairment in occupational functioning or in usual social activities or relationships with others, or to necessitate hospitalisation. There are no psychotic features.

### Manic Episode

An episode is characterised by an abnormally elevated, expansive, or irritable mood lasting at least seven days (or any duration if hospitalisation is required). Three or more of the following symptoms (four if the mood is only irritable) are present:

• inflated self-esteem or grandiosity
• decreased need for sleep
• increased talkativeness
• flight of ideas or the feeling that thoughts are racing
• distractibility
• increase in goal-directed activity or psychomotor agitation
• excessive involvement in pleasurable activities that have a high potential for painful consequences.

The episode causes marked impairment in occupational functioning, usual social activities, or relationships with others.

The episode may also necessitate hospitalisation to prevent harm to self or others. Psychotic features may be present.

### Bipolar I and II Disorders

Bipolar I and Bipolar II Disorders are mutually exclusive.

#### Bipolar I Disorder

This disorder is characterised by the occurrence of one or more Manic Episodes. Often the person has also had one or more Major Depressive Episodes.

#### Bipolar II Disorder

This disorder is characterised by the presence of either:

• Mania (excited episodes) and Major Depressive Episode
• Hypomania (with episodes lasting 14 days or longer) and Major Depressive Episode with the person never having had a Manic Episode.

#### DSM-IV Substance Use disorders

The study 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:

• cannabinoids (e.g., marijuana)
• sedatives (e.g., serepax, valium)
• stimulants (e.g., amphetamines, speed).

### Alcohol Abuse

A maladaptive pattern of alcohol use leading to clinically significant impairment or distress. It is evident that alcohol is responsible for or substantially contributes to physical or psychological harm, or dysfunctional behaviour. A diagnosis was achieved if one or more of the following problems occurred in the same 12-month period:

• failure to fulfil key role obligations at school, work or at home
• recurrent alcohol use in situations which are physically hazardous
• recurrent alcohol-related legal problems
• continued alcohol use despite social and interpersonal problems caused or exacerbated by the effects of alcohol.

Hierarchy rules have been applied to Alcohol Abuse. To meet criteria for the 'with hierarchy' version, a person cannot have met criteria for Alcohol Dependence.

### Alcohol Dependence

A maladaptive pattern of behaviour in which the use of alcohol takes on a much higher priority for the person that other behaviours that once had greater value. The central characteristic is the strong, sometimes overpowering, desire to consume alcohol despite significant alcohol-related problems. A diagnosis was achieved if three or more of the following problems occurred in the same 12-month period:

• tolerance, e.g., a need for markedly increased amounts of alcohol to achieve intoxication or desired effect
• withdrawal, e.g., characteristic withdrawal syndrome is manifested for alcohol
• using more alcohol or for longer periods than intended
• desire or unsuccessful efforts to cut down or control alcohol use
• a great deal of time obtaining, using, or recovering from the effects of alcohol
• reduction in important activities because of alcohol use
• continued use despite knowing it is causing significant physical or psychological problems that were likely caused or exacerbated by alcohol.
##### 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.

### Substance Abuse

The survey collected information on:

• Abuse-opioids
• Abuse-cannabinoids
• Abuse-sedatives
• Abuse-stimulants.

Substance Abuse is a maladaptive pattern of drug use leading to clinically significant impairment or distress. It is evident that the use of opioids/cannabinoids/sedatives/stimulants were responsible for or substantially contributed to physical or psychological harm, or dysfunctional behaviour. A diagnosis was achieved if one or more of the following problems occurred in the same 12-month period:

• failure to fulfil key role obligations at school, work or at home
• recurrent drug use in situations which are physically hazardous
• recurrent drug-related legal problems
• continued drug use despite social and interpersonal problems caused or exacerbated by the effects of the drug.

Hierarchy rules have been applied to Substance Abuse. To meet criteria for the 'with hierarchy' version, a person cannot have met a diagnosis of Dependence on the same type of substance during the same time period.

### Substance Dependence

The study collected information on:

• Dependence - opioids
• Dependence - cannabinoids
• Dependence - sedatives
• Dependence - stimulants.

Substance Dependence is a maladaptive pattern of drug use in which the use of drugs takes on a much higher priority for the person than other behaviours that once had greater value. The central characteristic is the strong, sometimes overpowering, desire to take the substance despite significant substance-related problems. A diagnosis was achieved if three or more of the following occurred for the same substance in the same 12-month period:

• tolerance, e.g., a need for markedly increased amounts of the drug to achieve intoxication or desired effect
• withdrawal, e.g., characteristic withdrawal syndrome is manifested for the drug
• using more of the drug or for longer periods than intended
• desire or unsuccessful efforts to cut down or control drug use
• a great deal of time obtaining, using, or recovering from the effects of the drug
• reduction in important activities because of drug use
• continued use despite knowing it is causing significant physical or psychological problems that were likely caused or exacerbated by the drug.

## Severity Measure

### Level of severity

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.

### Severe

A person was considered to have a severe level of impairment if any one of the following occurred in the 12 months prior to interview:

• a diagnosis of Bipolar I Disorder
• Substance Dependence with serious role impairment (two effects experienced 'a lot')
• a suicide attempt and any mental disorder
• at least two areas of severe role impairment in the Sheehan Disability Scale domains because of a mental disorder
• overall functional impairment at a level found in the National Comorbidity Survey Replication (NCS-R) to be consistent with a Global Assessment of Functioning (GAF) Score of 50 or less, in conjunction with a mental disorder.

More information on the calculation of functional impairment and the Global Assessment of Functioning (GAF) Score is provided below.

The following criteria were also considered:

• WMH-CIDI 3.0 version - a person must have also experienced substance dependence with physiological dependence
• New Zealand version - a person must have also experienced substance dependence with serious role impairment (two effects experienced 'a lot')
• Australian version - a person did not require a separate specification of impairment due to substance use. Additionally, their scores on the Sheehan Disability Scale for Substance Use disorders were added to the scores from other modules.

### Moderate

A person was considered to have a moderate level of impairment if they had a 12-month mental disorder and they were not classified as severe, reported at least moderate interference in any Sheehan Disability Scale domains, or had Substance Dependence without substantial impairment.

The following criteria were also considered:

• WMH-CIDI 3.0 version - a person must have also experienced substance dependence without physiological dependence
• New Zealand version - a person must have also experienced substance dependence without serious role impairment.

### Mild

A person was considered to have a mild level of impairment if they had a 12-month mental disorder, and they were not classified as severe or moderate.

### Global Assessment of Functioning (GAF) Score

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.

### Days out of role

The maximum number of days out of role was derived from responses to various questions within the diagnostic modules (e.g., Depressive Episode, Agoraphobia, Mania, etc). The calculation did not include any days out of role for Substance Use disorders, except for the Australian version.

The maximum number of days out of role was then categorised as follows:

• 1-6 days
• 7-50 days
• 51-365 days

People who had 'no interference' on the Sheehan Disability Scale were assigned '0' days. Where there was a 'not known' or 'not stated' value for the days out of role, a median number of days out of role was assigned.

### Sheehan Disability Scale

The Sheehan Disability Scale was used to assess the level of interference in four life domains during the worst period of symptoms in the 12 months prior to interview. The four domains are:

• home management (e.g., cleaning, shopping, care of the house, etc.)
• ability to work
• ability to form and maintain close relationships with other people
• social life.

The Sheehan Disability Scale ranges from '0 to 10', with each number being attributed a notional level of interference:

Sheehan Disability Scale, by level of interference
ScoreCategory
0None
1-3Mild
4-6Moderate
7-9Severe
10Very severe

People were asked to select the number that best described the level of interference their symptoms had on each of the domains. From responses in each of the diagnostic modules, a score was calculated for each domain, representing mild, moderate, or severe interference. The calculation did not include any days out of role for Substance Use disorders, except for the Australian version. The scores were as follows:

Sheehan disability scale, by life domains
MildModerateSevere
Home0-78-910
Work0-67-89-10
Close relationships0-789-10
Social life0-67-89-10

An overall level of impairment (mild, moderate, or severe) was derived using each of the domain scores. Where a person had 3 or 4 domains rated as severe, they received an overall assessment of 'severe'; where they had 2 to 4 domains rated as mild, they received an overall assessment of 'mild', otherwise they received an overall assessment of 'moderate'.

### Predicted GAF Score

The predicted Global Assessment of Functioning (GAF) Score is based on the following:

##### GAF Score of 50 or less

Maximum number of days out of role = 7-50 days or 51-365 days; and

Sheehan Disability Scale domain score = severe

##### GAF Score of 51 or more

Maximum number of days out of role = 1-6 days; and

Sheehan Disability Scale domain score = mild.

## Other mental health topics

### Lived experience of suicide

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.

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.

#### Suicidal thoughts and behaviours related to Depression

• 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 2020-21 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 2020-21.

### Self-harm

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 2020-21.

### Disordered Eating

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 2020-21.

## Health Service Utilisation

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.

### Consultations

Within the service utilisation module people were asked about consultations with health professionals including:

• general practitioners (GP)
• psychiatrists
• psychologists
• mental health nurses
• other mental health professionals (including social workers, counsellors, or occupational therapists)
• specialist doctors or surgeons (including cardiologists, gynaecologists, or urologists)
• other health professionals (including dieticians, physiotherapists, or pharmacists).

For each type of health professional endorsed they were asked further questions about consultations for their mental health including the number of consultations, how long consultations lasted, how they were paid for, out of pocket expenses, mode of consultation, and whether they were still seeing the health professional for mental health problems.

For the 12 months prior to interview, people were asked about hospital admissions relating to their mental health problems. Mental health problems included, but were not restricted to, things such as stress, anxiety, depression, or dependence on alcohol or drugs. They were asked to provide the number of overnight admissions, the total number of nights admitted, and whether they were a public or private patient.

### Perceived need for help

People who used services for mental health problems (i.e., consulted a health professional or were admitted to hospital overnight) in the 12 months prior to interview were asked to identify the help they received from a list of five types of assistance:

• information (about mental illness, its treatment, and available services)
• medication
• counselling (psychotherapy, cognitive behaviour therapy or counselling)
• social intervention (help to sort out housing or money problems or to meet people for support or company)
• skills training (help to improve their ability to work, to use their time, to look after themselves or their home).

For each type of assistance, they were asked if they received as much help as they needed and if not, the main reason this was not received.

People who did not use services for mental health problems, but who had symptoms that indicated a potential mental disorder (e.g., feeling sad or uninterested, excitable or irritable, worried or anxious, problems with alcohol use or drugs, etc) were asked whether they felt they needed any help from the list of five types of assistance. For each type of assistance identified, people were asked to select the main reason they did not seek help from a list of categories.

Responses to the perceived need for help questions were classified as:

• no need - people who were not receiving help and felt that they had no need for it
• need fully met - people who were receiving help and felt that it was adequate
• need partially met - people who were receiving help, but not as much as they felt they needed
• need not met - people who were not receiving help but felt that they needed it.

### Digital service use

Apart from the consultations with health professionals outlined previously, people were asked about other types of services that they used for their mental health problems in the 12 months prior to the survey interview over the phone or the internet or using other digital technology. Information was collected about the use of:

• Crisis support or counselling services (e.g., Lifeline)
• Treatment programs, training, assessments, or other tools to improve mental health (e.g., MindSpot, MoodGym, MyCompass)
• Mental health support groups, forums, or chat rooms (e.g., SANE, Beyond Blue, or CanTeen forums)
• Information about mental illness, treatment options or services

For each type of help used (excluding information about mental illness, treatment options or services), people were asked how many times they used it, whether a health professional was involved, and the mode of access.

### Comparability with 2007

In 2007, people were also asked to indicate whether they consulted a ‘Complementary/ alternative therapist such as a herbalist or naturopath’. In 2020-21 this category was not collected separately, however people may have included these in the ‘Other mental health professional’ or ‘Other health professional’ categories.

The category ‘Other mental health professional’ was labelled ‘Other professional providing specialist mental health services’ in 2007. The category ‘Other health professional’ was labelled ‘Other professional providing general services’. In 2007 both categories used the same examples of health professionals, i.e., ‘social worker, counsellor, occupational therapist’. In 2021, the examples provided for ‘Other health professional’ were ‘dietician, physiotherapist, pharmacist (advice only).

## Other scales and measures

### Kessler Psychological Distress Scale Plus (K10+)

The Kessler Psychological Distress Scale (K10) is a widely used indicator, which gives a simple measure of psychological distress. It is not a diagnostic tool but is an indicator of psychological distress.

The K10 is based on a person's emotional state during the 4 weeks prior to the survey interview. People were asked a series of 10 questions, about how often they felt:

1. tired for no good reason
2. nervous
3. so nervous nothing could calm them down
4. hopeless
5. restless or fidgety
6. so restless that they could not sit still
7. depressed
8. that everything was an effort
9. so sad that nothing could cheer them up; and
10. worthless.

For each question, an answer was provided using a five-level response scale, based on the amount of time a person reported experiencing the problem. The response scale corresponded to the following:

• none of the time
• a little of the time
• some of the time
• most of the time
• all of the time.

If a person selected 'none of the time' for questions 2 or 5 they were not asked the follow-on questions at 3 or 6 but were skipped to subsequent questions at 4 or 7 respectively.

Scores for the 10 questions were put together, with a minimum possible score of 10 and a maximum possible score of 50. Low scores indicate low levels of psychological distress, and high scores indicate high levels of psychological distress. The scores output were:

Level of psychological distress
CategoryScore
Low10-15
Moderate16-21
High22-29
Very High30-50

Four ‘plus’ questions are used to assess functioning and how often the feelings were caused by physical health problems.

#### Comparability with 2007

There were slight changes to the question wording, with the 2020-21 study referring to the 4 weeks prior to interview, compared to the 30 days prior to interview in 2007.

In 2007, questions 8 and 9 of the K10 were asked in the reverse order and the endorsement of 'none of the time' for question 7 resulted in a person being skipped to question 9. Additionally, the 2007 questions asked how often the person felt so ‘depressed’ rather than so ‘sad’ that nothing could cheer them up.

### Living in the Community Questionnaire - Summary (LCQ-S)

A selected group of questions from the Living in the Community Questionnaire - Summary (LCQ-S) were included in the study for the first time in 2020-21. The LCQ-S was developed by the Australian Mental Health Outcomes and Classification Network (AMHOCN) to assess social support and societal participation of Australians.

### World Health Organisation Disability Assessment Schedule 2.0 (WHODAS 2.0)

The WHO Disability Assessment Schedule (WHODAS) 2.0 is a simple tool used to assess health and disability. It directly relates to the concepts in the International Classification of Functioning, Disability and Health (ICF). It covers six domains of functioning including:

• Cognition – understanding and communicating
• Mobility– moving and getting around
• Self-care– hygiene, dressing, eating & staying alone
• Getting along– interacting with other people
• Life activities– domestic responsibilities, leisure, work, and school
• Participation– joining in community activities.

For each question, an answer was provided using a five-level response scale, based on the amount of difficulty a person experienced in undertaking the activity, on average, over the last 30 days due to their health conditions. The response scale corresponded to the following:

• None
• Mild
• Moderate
• Severe
• Extreme/Cannot do

The 12-item version of the questionnaire was used for the 2020-21 study.