Provisional Mortality Statistics methodology

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Reference period
Jan-Nov 2020
Released
24/02/2021

Explanatory notes

Scope and coverage

Scope for all ABS mortality statistics

The scope of the statistics includes:

  • Deaths that occurred and were registered in Australia, including deaths of persons whose usual residence is overseas;
  • Deaths occurring within Australian Territorial waters;
  • Deaths occurring in Australian Antarctic Territories or other external territories (including Norfolk Island);
  • Deaths occurring in transit (i.e. on ships or planes) if registered in the State of 'next port of call'; and
  • Deaths of Australian Nationals overseas who were employed at Australian legations and consular offices (i.e. deaths of Australian diplomats while overseas) where able to be identified.
     

The scope of the statistics excludes:

  • Deaths of Australian residents that occurred outside Australia but have been registered by individual Registrars;
  • Repatriation of human remains where the death occurred overseas;
  • Deaths of foreign diplomatic staff in Australia (where these are able to be identified); and
  • Stillbirths (fetal deaths).
     

Differences in scope for this report compared with Deaths, Australia (cat. no. 3302.0) and Causes of Death, Australia (cat. no. 3303.0)

This report contains statistics compiled using different methods to those used when compiling annual data on deaths and causes of death. Key differences include:

  1. This report focusses only on doctor certified deaths. Annual reports cover all deaths including those that are doctor certified and those that were referred to a coroner.
  2. Data in this report are based on the date of occurrence of the death. Annual reports generally present data based on date of registration.
  3. Data in this report are based on the state or territory of registration. Data in annual reports are based on the state or territory of usual residence of the deceased.
  4. Data in this report are considered to be provisional. Data released in annual reports are considered to be final (with the exception of revisions for coroner referred deaths).
     

Data for the current reference period and data used to derive baseline counts (maximum, minimum and average) are based on these methods enabling strong comparison over time.

For more information regarding the scope of the annual Deaths, Australia and Causes of Death, Australia publications see Explanatory notes on the Methodology page in catalogue numbers 3302.0 and 3303.0 on the ABS website.

Doctor certified deaths and coroner certified deaths

When a death occurs, the cause of that death is either certified by a doctor using a Medical Certificate of Cause of Death (MCCD), or the death is referred to a coroner for further investigation. Data in this report cover only those deaths that are certified by a doctor. In Australia approximately 86-89% of deaths are certified by a doctor.

Almost all external causes of death (e,g. suicides, accidents and assaults) are referred to a coroner and are therefore not covered in this report.

Although there is variation across jurisdictions in what constitutes a death that is reportable to a coroner, they are generally reported in circumstances such as:

  • where the person died unexpectedly and the cause of death is unknown
  • where the person died in a violent or unnatural manner
  • where the person died during, or as a result of an anaesthetic
  • where the person was 'held in care' or in custody immediately before they died
  • where the identity of the person who has died is unknown.
     

Counts of deaths in this report will not be comparable with those reported in the annual Deaths, Australia or Causes of Death, Australia publications which include both doctor and coroner certified deaths.

Date of death versus date of registration

There are two dates that are recorded on a death registration for all deaths that occur in Australia - the date on which the death occurred and the date on which the death was registered. Data in this report are compiled on date of occurrence.

Date of occurrence and date of registration will differ for all deaths, and the length of time by which they differ can vary considerably. Deaths are not reported to the ABS until they are registered, so the length of time between death and registration affects:

  • The timeliness of information reported; and
  • The ability to measure true change in mortality over time.
     

The average time lag between death and registration can vary, although in general deaths certified by a doctor are registered sooner. Coroner certified deaths undergo extensive investigative processes which can delay registration times.

As lag times between death and registration are longer for coroner referred deaths, these are excluded from these reports.

State or territory of registration versus usual residence

Data in this release are compiled by state or territory in which the death was registered. In the majority of cases, the death is registered in the state in which it occurred. Data in the annual Deaths, Australia and Causes of Death, Australia reports are compiled by the state or territory of usual residence of the deceased, regardless of where in Australia the death occurred and was registered.

Deaths of persons usually resident overseas which occur in Australia are included in the state/territory in which their death was registered. They are also included in counts of deaths based on usual residence of the deceased.

Provisional data versus final data

Statistics in this release are provisional and will be subject to additional processes prior to being released as part of the annual Deaths and Causes of Death datasets. Changes that may occur are:

  • The number of deaths may change.
  • Demographic variables may change.
  • The causes of death may change.
     

Counts of deaths in the annual Deaths, Australia (cat. no. 3302.0) and Causes of Death, Australia (cat. no. 3303.0) are considered final. Causes of death for coroner referred deaths are subject to a revisions process. Further information on this revisions process can be found in the Explanatory notes in the Methodology for Causes of Death, Australia (cat. no. 3303.0).

As registrations for deaths that occurred in previous reference periods are sent to the ABS, these will be counted in their date of occurrence and therefore each release will represent a more complete count of the number of deaths that occurred in that reference period.

Data can be impacted by changes in practices within one or more of the Registries of Births, Deaths and Marriages and therefore caution should be exercised when assessing week to week movements.

Statistical output

Baseline numbers and average collection times

Mortality data for 2020 are compared to an average baseline. The baseline is an arithmetic average of the previous 5 years of deaths from 2015 to 2019 based on year and week of occurrence. Minimum and maximum counts from 2015-19 are also included to provide an indication of the range of previous counts.

Baselines are compiled based on weekly counts of deaths from all causes and for specified causes of death. Weekly baseline information strengthens comparability by accounting for seasonal patterns of mortality. While baselines provide a point for comparison they do not provide an indication of the statistical significance of any deviation from that baseline.

International Classification of Diseases (ICD)

The International Classification of Diseases (ICD) is the international standard classification for epidemiological purposes and is designed to promote international comparability in the collection, processing, classification, and presentation of causes of death statistics. The classification is used to classify diseases and causes of disease or injury as recorded on many types of medical records as well as death records.

The ICD is revised periodically to incorporate changes in the medical field. Currently the ICD 10th revision is used for Australian causes of death statistics.

The ICD-10 is a variable-axis classification meaning that the classification does not group diseases only based on anatomical sites, but also on the type of disease. Epidemiological data and statistical data are grouped according to:

  • epidemic diseases;
  • constitutional or general diseases;
  • local diseases arranged by site;
  • developmental diseases; and
  • injuries.
     

For example, a systemic disease such as sepsis is grouped with infectious diseases; a disease primarily affecting one body system, such as a myocardial infarction, is grouped with circulatory diseases; and a congenital condition, such as spina bifida, is grouped with congenital conditions.

For further information about the ICD refer to WHO International Classification of Diseases (ICD).

The versions of the ICD 10th Revision are available online.

Updates to ICD-10

The Update and Revision Committee (URC), a WHO advisory group on updates to ICD-10, maintains the cumulative and annual lists of approved updates to the ICD-10 classification. The updates to ICD-10 are of numerous types including the addition and deletion of codes, changes to coding instructions and modification and clarification of terms.

From the 2013 reference year, the ABS implemented a new automated coding system called Iris. The 2013-2017 data coded in the Iris system applied an updated version of the ICD-10 (2013 version for 2013 data, and 2015 version for 2014-2017 data) when coding multiple causes of death, and when selecting the underlying cause of death. For details of further impacts of this change from 2013 data onwards, please see the ABS Implementation of the Iris Software: Understanding Coding and Process Improvements Technical Note in the Causes of Death, Australia, 2013 (cat. no. 3303.0) publication.

The 2018 reference year cause of death data presented in this publication were coded using version 5.4.0 of Iris software. This system replaced Iris version 4.4.1 which was used to code the 2013-2017 cause of death data. Version 5.4.0 of the Iris software applied the WHO ICD updates (2016 version) which have resulted in changes to output. For more information on this and the Iris product see Technical Note Updates to Iris coding software: Implementing WHO updates and improvements in coding processes in the Causes of Death, Australia, 2018 (cat. no. 3303.0) publication.

The 2019 data presented in this publication were coded using version 5.6.0 of Iris software, which used the 2019 version of the WHO ICD updates.

The cumulative list of ICD-10 updates can be found online.

Coding of COVID-19

In response to the COVID-19 pandemic, the WHO issued the ICD emergency codes U07.1 COVID-19, virus identified and U07.2 COVID-19 virus not identified. These codes are used when assigning causes to confirmed or suspected COVID-19 deaths.

Due to the public health importance of COVID-19, the WHO directed that the new coronavirus strain be recorded as the underlying cause of death, i.e. the disease or condition that initiated the train of morbid events, when it is recorded as having caused death.

All deaths due to COVID-19 analysed in the appended article in the Jan-Mar Provisional Mortality Statistics release have an underlying cause of death code of U07.1 COVID-19, virus identified.

Deaths due to COVID-19 are included in the total for all deaths certified by a doctor. They are not included in deaths due to respiratory diseases or any of the other specified causes included in this report.

COVID-19 infections

The number of weekly COVID-19 infections (not deaths) shown in Graph 1 of this report reflects the number of newly confirmed COVID-19 cases reported and updated daily by the Australian Department of Health. Information on newly identified COVID-19 infections is sourced from State and Territory Departments of Health and collated into a national figure by the Department of Health. Data was extracted by the ABS on 07 January 2020.

Confidentialisation

The ABS observes strict confidentiality protocols as required by the Census and Statistics Act (1905). This may restrict access to data at a very detailed level.

Data cells with small values have been randomly assigned to protect confidentiality. As a result some totals will not equal the sum of their components. Cells with 0 values have not been affected by confidentialisation.

Age-standardised death rates (SDRs) and population data

Age-standardised death rates enable the comparison of death rates over time and between populations of different age-structures. The ABS uses the direct method of age-standardisation as it allows for valid comparisons of mortality rates between different study populations and across time. This method was agreed to by the ABS, Australian Institute of Health and Welfare (AIHW) and other stakeholders. For further information see: AIHW (2011) Principles on the use of direct age-standardisation in administrative data collections: for measuring the gap between Indigenous and non-Indigenous Australians. Cat. no. CSI 12. Canberra: AIHW.

The direct method has been used throughout the publication and data cubes for age-standardised death rates. Age-standardised death rates for specific causes of death with fewer than a total of 20 deaths have not been published due to issues of robustness. For further information, see Appendix: Principles on the use of direct age-standardisation, from Deaths, Australia, 2010.

Age-standardised death rates (SDRs) in this publication have been calculated using quarterly population estimates and short-term population projections. SDRs for baseline years (2015-2019) have been calculated using quarterly estimated resident population (ERP) published in 'National, state and territory population, March 2020' released on 24 September, 2020. See 'Revision status' in the Methodology section of that release for details of the status of quarterly population data used for calculating baseline rates. The quarterly estimates used for calculating weekly rates for the relevant year are as follows: weeks 1-13  (March Qtr ERP); weeks 14-26 (June Qtr ERP); weeks 27-39 (Sept. Qtr ERP) and; weeks 40-53 (Dec. Qtr ERP).

Age-standardised death rates for 2020 are based on population estimates (published in 'National, state and territory population') or short-term population projections. Since the most recently released population estimates lag the provisional mortality data by several months, short-term population projections have been used for calculating rates for some weeks. The population projections are based on the most recently available population estimate plus projected components of population growth. Projected births, deaths and interstate migration are based on previously observed data published in 'National, state and territory population'. Projected overseas migration is based on the latest overseas arrivals and departures data, as well as previously observed overseas migration published in 'National, state and territory population'. See the relevant footnotes in the data cubes of this publication for specific details of the ERP/projections used for the calculation of SDRs for weeks in 2020.

Confidence intervals

Mortality rates derived from administrative data counts may be subject to natural random variation, especially for small counts. Confidence intervals (CIs) for an SDR can help quantify this variability. CIs included in this publication indicate a 95% probability that the 'true' SDR is contained within the lower and upper limits of the CI. CIs have been calculated using the standard method and formulae can be sourced from Breslow and Day (1987) in the 'Statistical methods in cancer research' publication. Further information on the calculation of CIs can also be found on the METeOR website (see National Indigenous Reform Agreement: PI 08 - Tobacco smoking during pregnancy, 2016).

Registration process

The registration of deaths is the responsibility of the eight individual state and territory Registrars of Births, Deaths and Marriages.

In order to complete a death registration, the death must be certified by either a doctor using the Medical Certificate of Cause of Death (MCCD) or by a coroner. This release includes deaths that have been certified by a doctor only.

For doctor certified deaths, information about the cause of death is supplied by the medical practitioner certifying the death via the MCCD (or MCCPD for perinatal deaths). Other information about the deceased is supplied via the Death Registration Form, which is informed by a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred. Registrars require information from both sources to complete a death registration. It should be noted that legislative requirements for registering a death differ across jurisdictions and this can impact on the timeliness of registration and reporting.

The information is provided to the Australian Bureau of Statistics by individual Registrars for processing, coding and compilation into aggregate statistics. Registrars report all deaths that were registered in a given month to the ABS at the start of the following month.

The following diagram shows the process undertaken in producing cause of death statistics for doctor certified deaths in Australia.
 

Image: flowchart showing doctor certified death registration process in Australia
The flow chart begins with a death event. There are two arrows under a death event. When a death occurs a funeral director assists the family in filling out a death registration statement and this is lodged with the Registry of Births, Deaths and Marriages. This pathway is outlined under the first arrow in the diagram under death event. All deaths must be certified with a cause of death. The second pathway under death event reflects this process. A decision must be made as to whether the death is reportable or not. If no, a death that is not reportable will be certified by a doctor then registered with the Registrar of Births, Deaths and Marriages. If yes, a death that is reportable is referred to a coroner for investigation. These deaths are out of scope of this report. The flowchart then progresses to show how the ABS receives and works with mortality information. The ABS receives monthly files from the Registrars containing information about the deaths that were registered each month. The ABS then amalgamates and checks the records, assigns cause of death codes to each record, validates the dataset and produces statistical output.

Glossary

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Age standardised death rates (SDRs)

Age-standardised death rates enable the comparison of death rates over time and between populations of different age-structures. The ABS uses the direct method of age-standardisation as it allows for valid comparisons of mortality rates between different study populations and across time.

Associated causes of death

All causes listed on a death certificate other than the underlying cause.

Average

Arithmetic mean, calculated by the sum of the numbers divided by how many numbers are being averaged. This publication presents average data for the period 2015-2019 to compare to 2020 data. The average is also referred to as the baseline.

Baseline

A baseline is a fixed point of reference that can be used for comparison purposes. In this publication it is the arithmetic average of the previous 5 years of deaths from 2015-2019 based on year and week of occurrence. Baselines are compiled based on weekly counts of deaths from all causes and for specified causes of death. While baselines provide a point for comparison they do not provide an indication of the statistical significance of any deviation from that baseline.

Case fatality rate

The proportion of people who die from a disease amongst the number of people diagnosed with that disease. 

Cause of death

The causes of death entered on the Medical Certificate of Cause of Death are all those diseases, morbid conditions or injuries that either resulted in or contributed to death and the circumstances of the accident or violence that produced any such injuries.

Certifier type

Deaths may be certified by either a medical practitioner, using the Medical Certificate of Cause of Death, or a coroner. Natural causes are predominantly certified by doctors, whereas external and unknown causes are usually certified by a coroner. However, some deaths for natural causes are referred to coroners for investigation, for example, unaccompanied deaths.

Confidence intervals

Confidence intervals included in this publication indicate a 95% probability that the 'true' age standardised death rate is contained within the lower and upper limits of the confidence interval.

Confidentialised

From 2006, data cells with small values have been randomly assigned to protect confidentiality. As a result some totals will not equal the sum of their components. It is important to note that cells with 0 values have not been affected by confidentialisation. Data presented at the Australia level (with exception to youth suicide tables) is not confidentialised - the death counts presented are exact counts.

Coroner certified deaths

Deaths that were certified by a coroner as opposed to a doctor.

Counts of death

A form of multiple cause of death analysis that is a calculation of the number of people who have died with a particular disease/s or disorder/s.

COVID-19 death

A death that has been certified by a doctor as having been caused by the new Coronavirus strain.

Data cubes

Data cubes are a series of spreadsheets which present Causes of Death data. Causes of Death data cubes can be found on the web page in the Data downloads section.

Date of occurrence

Data presented on a date of occurrence basis relate to the date the death occurred rather than when it was registered with the relevant state or territory Registrar of Births, Deaths and Marriages.

Death

Death is the permanent disappearance of all evidence of life after birth has taken place. The definition excludes all deaths prior to live birth. For the purposes of the Deaths and Causes of Death collections of the Australian Bureau of Statistics, a death refers to any death that occurs in, or en route to, Australia and is registered with a state or territory Registry of Births, Deaths and Marriages.

Doctor certified deaths

Deaths that were certified by a doctor or medical practitioner, which were not required to be referred on to a coroner. Deaths certified by a doctor represent around 86%-89% of all deaths each year. Doctor certified deaths are not subject to the revisions process.

Excess mortality

An epidemiological concept typically defined as the difference between the observed number of deaths in a specified time period and the expected numbers of deaths in that same time period. In this publication, the average, minimum and maximum deaths for 2015-19 are provided to give an indication of the expected number of deaths. Estimates of excess deaths can provide information about the burden of mortality potentially related to an event such as the COVID-19 pandemic, either directly or indirectly attributable to that event.

External causes of death

Deaths due to causes external to the body (for example suicide, transport accidents, falls, poisoning etc.). These relate to ICD-10 codes V01-Y98.

Final data

Data that has no further changes that will be applied to the number, demographic components or causes of death.

ICD

International Statistical Classification of Diseases and Related Health Problems. The purpose of the ICD is to permit the systematic recording, analysis, interpretation and comparison of mortality and morbidity data collected in different countries or areas and at different times. The ICD, which is endorsed by the World Health Organization (WHO), is primarily designed for the classification of diseases and injuries with a formal diagnosis. The ICD-10 is the current classification system, which is structured using an alphanumeric coding scheme. Each disease or health problem listed on the death certificate is assigned a 3-character identification code. Cause of death statistics can be produced for aggregates of these, for example, chapter level (letter), 2-character code (first two characters of the assigned code), and 3-character code (first three characters of the assigned code). See the Explanatory Notes for more information on ICD. Further information also is available from the WHO website.

Maximum

The highest value in a series of numbers. In this publication, the maximum of the values for 2015-2019 is provided along with the minimum and average to use as a baseline to compare to 2020 data.

Minimum

The lowest value in a series of numbers. In this publication, the minimum of the values for 2015-2019 is provided along with the maximum and average to use as a baseline to compare to 2020 data.

Morbid train of events

The events and diseases that lead to death.

Mortality

See Death.

Multiple causes of death

All morbid conditions, diseases and injuries entered on the death certificate. These include those involved in the morbid train of events leading to death which were classified as either the underlying cause, the immediate cause, or any intervening causes, and those conditions that contributed to death but were not related to the disease or condition causing death. For deaths where the underlying cause was identified as an external cause (for example, injury or poisoning, etc.) multiple causes include circumstances of injury and the nature of injury as well as any other conditions reported on the death certificate.

Natural cause of death

Deaths due to diseases (for example diabetes, cancer, heart disease etc.) that are not external or unknown.

Provisional

Subject to change. The 2020 data in this publication are subject to additional processes prior to being released as part of the annual Deaths and Causes of Death datasets at which stage they will be considered Final. Changes may occur to the number of deaths, demographic and causes of death information. As registrations for deaths that occurred in previous reference periods are sent to the ABS, these will be counted in their date of occurrence and therefore each release will represent a more complete count of the number of deaths that occurred in that reference period.

Reference year

Data in the Deaths and Causes of Death publications are presented by reference year. The scope of a reference year includes deaths registered in the reference year and received by the ABS in the reference year or in the first quarter of the subsequent year. It also includes any deaths registered in the years prior to the reference year but not received by the ABS until the reference year or the first quarter of the subsequent year, provided those records have not been included in any statistics from earlier periods.

Registration year

Data presented on a year of registration basis relate to the date the death was registered with the relevant state or territory Registrar of Births, Deaths and Marriages. In most cases the year of registration and year of occurrence for a particular death will be the same, but in some cases there may be a delay between occurrence and registration of death.

Registry of Births, Deaths and Marriages

Each state and territory has a Registry of Births, Deaths and Marriages. It is a legal requirement that all deaths are recorded by the relevant Registry for the state or territory in which the death occurred.

Reportable deaths

Deaths which are reported to a coroner. See the 'Doctor certified deaths and coroner certified deaths' section of the Explanatory Notes for further information on what constitutes a reportable death.

State or territory of registration

State or territory of registration refers to the state or territory in which the death was registered. It is the state or territory in which the death occurred, but is not necessarily the deceased's state or territory of usual residence.

State or territory of usual residence

State or territory of usual residence refers to the state or territory in which the person has lived or intended to live for a total of six months or more in a given reference year.

Underlying cause of death

The disease or injury that initiated the train of morbid events leading directly to death. Accidental and violent deaths are classified according to the external cause, that is, to the circumstances of the accident or violence which produced the fatal injury rather than to the nature of the injury.

Unknown cause of death

Deaths for which it is not possible to determine between a natural and an external cause.

Usual residence

Usual residence within Australia refers to that address at which the person has lived or intended to live for a total of six months or more in a given reference year.

Year of occurrence

Data presented on a year of occurrence basis relate to the date the death occurred rather than when it was registered with the relevant state or territory Registrar of Births, Deaths and Marriages.

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