3303.0 - Causes of Death, Australia, 2009 Quality Declaration
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 03/05/2011
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3 The registration of deaths is the responsibility of the eight individual state and territory Registrars of Births, Deaths and Marriages. As part of the registration process, information about the cause of death is supplied by the medical practitioner certifying the death or by a coroner. Other information about the deceased is supplied by a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred. The information is provided to the Australian Bureau of Statistics (ABS) by individual Registrars for coding and compilation into aggregate statistics. In addition, the ABS supplements this data with information from the National Coroners Information System (NCIS). The following diagram shows the process undertaken in producing cause of death statistics for Australia.
4 The data presented in this publication are also included in a series of data cubes that are available on the ABS website.
5 A Glossary is also provided which details definitions of terminology used.
6 These Explanatory Notes provide salient details relevant to the ABS Causes of Death collection.
2009 SCOPE AND COVERAGE
7 The statistics in chapters 1-7 relate to the number of deaths registered, not those which actually occurred, in the years shown. Number of deaths by year of occurrence are published in Chapter 8 and data cube 13.
Scope of causes of death statistics
8 The ABS Causes of Death collection includes all deaths that occurred and were registered in Australia, including deaths of persons whose usual residence is overseas. Deaths of Australian residents that occurred outside Australia may be registered by individual Registrars, but are not included in ABS deaths or causes of death statistics.
9 The current scope of the statistics includes:
10 The scope of the statistics excludes:
11 The scope for each reference year of the Death Registrations includes:
12 Death records received by ABS during the March quarter 2010 which were initially registered in 2009 (but for which registration was not fully completed until 2010) were assigned to the 2009 reference year. Any registrations relating to 2009 which were received by ABS from April 2010 were assigned to the 2010 reference year. Approximately 4% to 6% of deaths occurring in one year are not registered until the following year or later.
13 Prior to 2007, the scope for the reference year of the Death Registrations collection included:
Coverage of causes of death statistics
14 Ideally, for compiling annual time series, the number of events (deaths) should be recorded and reported as those occurring within a given reference period such as a calendar year. However, due to lags in registration of events, not all deaths are registered in the year that they occur. Therefore, the occurrence event is approximated by the ABS through the addition of the event on a state/territory register of deaths. Also, some additions to the register can be delayed in being received by the ABS from a Registrar (processing or data transfer lags).
In effect there are 3 dates attributable to each death registration:
15 A range of socio-demographic data are available from the ABS Causes of Death collection. Standard classifications used in the presentation of causes of death statistics include age, sex, birthplace, marital status, multiple birth and Indigenous status. Statistical standards for social and demographic variables have been developed by the ABS. Where these are not published in the Causes of Death publication or data cubes, they can be sourced on request from the ABS.
16 Within ABS causes of death statistics, marital status relates to registered marital status. Registered marital status refers to formally registered marriages or divorces for which the partners hold a certificate.
17 For further information about marital status refer to Family, Household and Income Unit Variables, 2005 (cat. no. 1286.0)
Australian Standard Geographical Classification (ASGC)
18 The ASGC is an hierarchical classification system consisting of six interrelated classification structures. The ASGC provides a common framework of statistical geography and thereby enables the production of statistics which are comparable and can be spatially integrated. ABS causes of death statistics are coded to Statistical Local Area (SLA) and can be produced for aggregates of these, for example, Statistical Division, Statistical Sub-Division and State. For further information about the ASGC refer to Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).
19 The ABS has developed a new standard classification for geography, the Australian Statistical Geography Standard (ASGS). The ASGS will be implemented for the 2011 Causes of Death reference period. For further information about the ASGS refer to Australian Statistical Geography Standard (ASGS) (cat. no. 1270.0.55.001).
Standard Australian Classification of Countries (SACC)
20 The SACC groups neighbouring countries into progressively broader geographic areas on the basis of their similarity in terms of social, cultural, economic and political characteristics. ABS causes of death statistics are coded using the SACC, as the collection includes overseas residents whose death occurred while they were in Australia.
21 Birthplaces within Australia are coded to the state/territory level where possible. The supplementary codes contain the relevant state and territory 4-digit codes.
22 For further information about the classification, refer to Standard Australian Classification of Countries (SACC), (Second Edition) (cat. no. 1269.0).
International Classification of Diseases (ICD)
23 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 has been revised periodically to incorporate changes in the medical field. Currently ICD 10th revision is used for Australian causes of death statistics.
24 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 is grouped according to:
25 For example, a systemic disease such as septicaemia 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.
26 For further information about the ICD refer to WHO International Classification of Diseases (ICD).
27 The ICD 10th Revision is also available online.
28 An ongoing issue for the ABS Causes of Death collection has been that the quality of the data can be affected by the length of time required for the coronial process to be finalised and the coroner case closed. For some time, these concerns have been raised by key users of causes of death data regarding the quality of external causes data (e.g. deaths due to intentional self-harm (Suicides), homicides, Sudden Infant Death Syndrome (SIDS) and motor vehicle accidents). The ABS have addressed these data quality concerns in two ways:
29 Up to and including deaths registered in 2006, ABS Causes of Death processing was finalised at a point in time. At this point, not all deaths registered in the reference year which were referred to the coroner, had been investigated, the case closed and relevant information loaded into the National Coroners Information System (NCIS). The coronial process can take several years if an inquest is being held or complex investigations are being undertaken. In these instances, the cases remain open on the NCIS. Coroners' cases that have not been closed can impact on data quality as less specific ICD codes often need to be applied in the absence of a coroners finding.
30 To improve the quality of ICD coding, all coroner certified deaths registered after 1 January 2007 are now subject to a revisions process. The revisions process enables the use of additional information relating to coroner certified deaths either 12 or 24 months after initial processing. This increases the specificity of the assigned ICD-10 codes over time. As 12 or 24 months of time has passed since initial processing, many coronial cases will be closed, with the coroner having determined the underlying cause of death and allowing the ABS to code a more specific cause of death. If the case remains open on the NCIS, ABS will investigate and use additional information from police reports, toxicology reports, autopsy reports and coroners' findings to assign a more specific cause of death to these open cases.
31 In this publication and associated data cubes, in addition to 2009 preliminary data, 2008 revised data and 2007 final data have also been published. See Technical Note: Causes of Death Revisions for further information on the impact of the revisions process.
32 As 2007 reference year data are the first series of data to be finalised through the revisions process, a review will be undertaken into the impact of the overall revisions process. The results of this review will be used to determine the most appropriate strategy for future revisions.
2009 MORTALITY CODING
33 The extensive nature of the ICD enables classification of causes of death at various levels of detail. For the purpose of this publication, data is presented according to the ICD at the chapter level, with further disaggregation for major causes of death.
34 To enable the reader to see the relationship between the various summary classifications used in this publication, all tables show in brackets the ICD codes which constitute the causes of death covered.
Updates to ICD-10
35 The Updating 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 addition and deletion of codes, changes to coding instructions and modification and clarification of terms.
36 The cumulative list of ICD-10 updates can be found online.
37 The ABS uses automated cause of death coding software (Medical Mortality Data System (MMDS)). The MMDS applies ICD rules to all death records, diseases and conditions listed on the death certificate. Approximately 70-80% of records can be coded using the MMDS without manual intervention.
External Causes of Death
38 Where an accidental or violent death occurs, the underlying cause is classified according to the circumstances of the fatal injury, rather than the nature of the injury, which is coded separately.
Leading Causes of Death
39 Ranking causes of death is a useful method of describing patterns of mortality in a population and allows comparison over time and between populations. However, different methods of grouping causes of death can result in a vastly different list of leading causes for any given population. A ranking of leading causes of death based on broad cause groupings such as 'cancers' or 'heart disease' does not identify the leading causes within these groups, which is needed to inform policy on interventions and health advocacy. Similarly, a ranking based on very narrow cause groupings or including diseases that have a low frequency, can be meaningless in informing policy.
40 Tabulations of leading causes presented in this publication are based on research presented in the Bulletin of the World Health Organisation, Volume 84, Number 4, April 2006, 297-304. The determination of groupings in this list is primarily driven by data from individual countries representing different regions of the world. Other groupings are based on prevention strategies, or to maintain homogeneity within the groups of cause categories.
41 A number of organisations publish lists of leading causes of death. However, the basis for determining the leading causes may vary. For example, many lists are based on Years of Potential Life Lost (YPLL) and are designed to present data based on the burden of mortality and disease to the community. The ABS listing of leading causes is based on the numbers of deaths and is designed to present information on incidence of mortality rather than burden of mortality.
Years of Potential Life Lost (YPLL)
42 Years of Potential Life Lost (YPLL) measures the extent of 'premature' mortality, which is assumed to be any death between the ages of 1-78 years inclusive, and aids in assessing the significance of specific diseases or trauma as a cause of premature death.
43 Estimates of YPLL are calculated for deaths of persons aged 1-78 years based on the assumption that deaths occurring at these ages are untimely. The inclusion of deaths under one year would bias the YPLL calculation because of the relatively high mortality rate for that age, and 79 years was the median age at death when this series of YPLL was calculated using 2001 as the standard year. As shown below, the calculation uses the current ABS standard population of all persons in the Australian population at 30 June 2001. This standard is revised every 10 years.
44 YPLL is derived from:where: = adjusted age at death. As age at death is only available in completed years the midpoint of the reported age is chosen (e.g. age at death 34 years was adjusted to 34.5). = registered number of deaths at age due to a particular cause of death.
YPLL is directly standardised for age using the following formula: where the age correction factor is defined for age as: where: = estimated number of persons resident in Australia aged 1-78 years at 30 June 2009 = estimated number of persons resident in Australia aged years at 30 June 2009 = estimated number of persons resident in Australia aged years at 30 June 2001 (standard population)= estimated number of persons resident in Australia aged 1-78 years at 30 June 2001 (standard population)
45 The data cubes contain directly standardised death rates and YPLL for males, females and persons. In some cases the summation of the results for males and females will not equate to persons. The reasons for this is that different standardisation factors are applied separately for males, females and persons.
State and Territory Data
46 Causes of death statistics for states and territories in this publication have been compiled in respect of 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.
47 Statistics compiled on a state or territory of registration basis are available on request.
Coroner Certified Deaths
48 In compiling causes of death statistics, the ABS employs a variety of measures to improve quality, which include:
49 The quality of causes of death coding can be affected by changes in the way information is reported by certifiers, by lags in completion of coroner cases and the processing of the findings. While changes in reporting and lags in coronial processes can affect coding of all causes of death, those coded to Chapter XVIII: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified and Chapter XX: External causes of morbidity and mortality are more likely to be affected because the code assigned within the chapter may vary depending on the coroner's findings (in accordance with ICD-10 coding rules).
50 Over time, improvements have been made to the quality of the causes of death data published by the ABS. Two processing improvements were introduced to the ABS Causes of Death collection in 2008 (the context and details of these improvements are described below). These improvements relate to the way the ABS codes coroner certified deaths and have had the effect of significantly improving the quality of cause of death codes assigned to coroner certified cases.
51 In order to complete a death registration, the death must be certified by either a doctor using the Medical Certificate of Cause of Death, or by a coroner. It is the role of the coroner to investigate the circumstances surrounding all reportable deaths and to establish wherever possible the circumstances surrounding the death, and the cause(s) of death. Generally most deaths due to external causes will be referred to a coroner for investigation; this includes those deaths which are possible instances of Intentional self-harm (Suicide).
52 When coronial investigations are complete, causes of death information is passed to the Registrar of Births, Deaths and Marriages, as well as to the NCIS. The ABS uses the NCIS as the only source of data to code coroner certified deaths. Where a case remains open on the NCIS at the time the ABS ceases processing and insufficient information is available to code a cause of death (e.g. a coroner certified death was yet to be finalised by the coroner), less specific ICD codes are assigned as required by the ICD coding rules.
53 The specificity with which open cases are able to be allocated an ICD-10 code is directly related to the amount and type of information available on the NCIS. The amount of information available for open cases varies considerably from no information to detailed police, autopsy and toxicology reports. There may also be interim findings of 'intent'.
54 The manner or intent of an injury which leads to death, is determined by whether the injury was inflicted purposefully or not (in some cases, intent cannot be determined) and, when it is inflicted purposefully (intentional), whether the injury was self-inflicted (suicide) or inflicted upon another person (assault).
55 The first of the new processing improvements introduced from 2008 relates to the way that the ABS utilises information on the Medical Certificate of Cause of Death. For both open and closed coroners cases, more time is now taken to investigate part 2 of the certificate when a non-specific underlying cause was shown in part 1. Part 2 of the certificate details conditions that may have contributed to the death but were not part of the sequence of events that led to death.
56 The second new processing improvement relates to the use of additional information available on the NCIS. Increased resources and time were spent investigating coroners reports to identify specific causes of death. This involved making increased use of police reports, toxicology reports, autopsy reports and coroners findings for both open and closed cases to minimise the use of non-specific causes and intents.
57 The introduction of these processes has resulted in improved data quality in relation to assigning unspecified cause codes to coroner certified deaths. There has been a decrease of 555 (47.8%) in the number of coroner certified deaths attributed to Other ill-defined and unspecified causes of mortality (R99) from 1,160 in 2007 (preliminary) to 605 in 2009 (preliminary).
58 As less specific codes are generally associated with open rather than closed coroner certified cases, the new processes have had the effect of significantly improving the quality of cause of death codes assigned to open cases. Additionally, a large number of deaths investigated by coroners are due to external causes, therefore the new processes have also had the effect of improving these data.
59 Prior to 2008, these two processes were not routinely followed in relation to coroner certified cases. However, they have been applied to the revised 2007 data and the preliminary and revised 2008 data.
60 The 2009 data provided in this publication has not yet been subjected to the revisions process, which will further improve the quality of the data. Therefore, the data on 2009 causes of death is considered preliminary and refers to the point in time when initial 2009 processing was finalised. The 2009 data will go through the revisions process twice, and will be released in the ABS Causes of Death publications in 2012 (2009 revised) and 2013 (2009 final).
61 The ABS Death Registrations collection identifies a death as being Indigenous where the deceased is identified as being of Aboriginal and/or Torres Strait Islander origin through the death registration process.
62 Identification of the deaths of Indigenous Australians can occur on Death Registration Forms and Medical Certificates of Causes of Death. However it is recognised that not all Indigenous deaths are captured through these processes, leading to under-identification. While data are provided to the ABS for the Indigenous status question for 98.9% of all deaths, there are concerns regarding the accuracy of the data.
63 There are several data collection forms on which people are asked to state whether they are of Aboriginal and/or Torres Strait Islander origin. Due to a number of factors, the results are not always consistent. The likelihood that a person will identify, or be identified, as an Aboriginal and/or Torres Strait Islander on a specific form is known as their propensity to identify.
64 Propensity to identify as an Aboriginal and/or Torres Strait Islander is determined by a range of factors, including:
65 In addition to those deaths where the deceased is identified as an Aboriginal and/or Torres Strait Islander, a number of deaths occur each year where Indigenous status is not stated on the death registration form. In 2009, there were 1,528 deaths registered in Australia for whom Indigenous status was not stated, representing 1.1% of all deaths registered.
66 Data presented in this publication may therefore underestimate the level of Aboriginal and/or Torres Strait Islander deaths and mortality in Australia. Caution should be exercised when interpreting data for Aboriginal and/or Torres Strait Islander Australians presented in this publication, especially with regard to year-to-year changes.
67 Chapter 7 of this publication and data cube 12 provide information on causes of death for Aboriginal and/or Torres Strait Islander Australians. Due to the data quality issues outlined below, detailed disaggregations of deaths of Aboriginal and/or Torres Strait Islander Australians are provided only for New South Wales, Queensland, Western Australia and the Northern Territory.
68 Due to the increased focus on the mortality rates of Aboriginal and/or Torres Strait Islander Australians, a number of projects have been undertaken to investigate the quality of these data. These include:
69 The ABS undertakes significant work aimed at improving Indigenous identification. Quality studies conducted as part of the Census Data Enhancement project have investigated the levels and consistency of Indigenous identification between the 2006 Census and death registrations. See Information Paper: Census Data Enhancement - Indigenous Mortality Quality Study, 2006-07 (cat. no. 4723.0), released on 17 November 2008.
70 An assessment of various methods for adjusting incomplete Indigenous death registration data for use in compiling Indigenous life tables and life expectancy estimates is presented in Discussion Paper: Assessment of Methods for Developing Life Tables for Aboriginal and Torres Strait Islander Australians, 2006 (cat. no. 3302.0.55.002), released on 17 November 2008.
DEATHS BY TYPE OF CERTIFIER
71 For deaths registered in 2009, 13.3% were certified by a coroner. There are variations between jurisdictions in relation to deaths certified by a coroner, ranging from 11.3% deaths certified by a coroner in Queensland to 32.6% of deaths certified by a coroner in the Northern Territory. The proportion of deaths certified by a coroner in 2009 is comparable to previous years.
72 All causes of death can be grouped to describe the type of death whether it be from a disease or condition, or from an injury or whether the cause is unknown. These are generally described as:
SPECIFIC ISSUES FOR 2009 DATA
73 As outlined below a number of issues should be taken into account by users when analysing the 2009 Causes of Death data.
74 Since 2006, there has been a significant increase in the number of deaths coded to Dementia (F01,F03). Updates to the coding instructions in ICD-10 has resulted in the assignment of some deaths shifting from Cerebrovascular diseases (I60-I69) to Vascular dementia (F01). In addition, changes to the Veterans’ Entitlements Act 1986 and Military Rehabilitation and Compensation Act 2004, and a subsequent promotional campaign targeted at health professionals, now allow for death from vascular dementia of veterans or members of the defence forces to be related to relevant service. This is believed to have had an effect on the number of deaths attributed to dementia.
Exposure to uncontrolled fire, not in building or structure (X01)
75 The number of deaths attributable to Exposure to uncontrolled fire, not in building or structure (X01), increased from 7 in 2008 to 165 in 2009. This increase is primarily due to deaths resulting from the Victorian bushfires. The 2009 Victorian Bushfires Royal Commission stated that there were 173 deaths resulting from the bushfires. Additional quality checks were conducted on cases relating to the Victorian bushfires and records were coded as per standard ICD rules.
76 The H1N1 influenza strain (commonly known as swine flu) was determined to be the underlying cause of 77 deaths in 2009. As a new strain of influenza, swine flu was not originally included in the ICD-10 classification. A decision was made by the WHO to include deaths associated with swine flu in Influenza due to certain identified influenza virus (J09).
Transport Accidents (V01-V79, Y32)
77 There were 1,290 deaths attributed to Road traffic accidents (V01-V79) in 2009, and a further 81 deaths coded as Crashing of a motor vehicle, undetermined intent (Y32). When making comparisons between road deaths from the ABS Causes of Death collection and road deaths from other sources, the scope and coverage rules applying to each collection should be considered. It should be noted that the number of road traffic related deaths attributed to transport accidents for 2009 is expected to change (and most likely increase) as data is subject to the revisions process, see Explanatory Notes 28-32.
Assault (X85-Y09, Y87.1)
78 The number of deaths recorded as Assault (X85-Y09, Y87.1) i.e. murder, manslaughter and their sequelae, published in the ABS Causes of Death publication, differ from those published by the ABS in Recorded Crime - Victims, Australia, 2009 (cat. no. 4510.0). Reasons for the different counts include differences in scope and coverage of the two collections, as well as legal proceedings that are pending finalisation. It is important to note that the number of deaths attributed to assault for 2009 is expected to change (and most likely increase) as Causes of Death data is subject to the revisions process, see Explanatory Notes 28-32.
79 The following codes may include cases which could potentially have been assaults but for which the intent was determined to be other than Assault (X85-Y09, Y87.1). Such cases cannot be separately identified in the final ABS Causes of Death statistics:
Intentional Self-Harm [Suicide] (X60-X84, Y87.0)
80 The number of deaths recorded as Intentional self-harm (Suicide)(X60-X84, Y87.0) has decreased over the last 10 years, from 2,367 in 2000 to 2,132 in 2009. This decrease can be partly attributed to the variances in the way the ABS has coded coroner certified deaths over time. See Explanatory Notes 48-60, for further information. This will have an influence on the number of deaths due to suicide, as the majority of open coroner cases are deaths due to external causes.
81 In addition, the number of deaths attributed to suicide for 2009 is expected to increase as data is subject to the revisions process, see Explanatory Notes 28-32 for further information on the causes of death revisions process.
82 Suicide deaths in children are an extremely sensitive issue for families and coroners. The number of child suicides registered each year is low in relative terms and is likely to be underestimated. For that reason this publication does not include detailed information about suicides for children aged under 15 years in the commentary or data cubes.
83 For processing of deaths registered from 1 January 2007, revised instructions for ABS coders were developed in order to ensure consistency in the coding of suicide deaths and compliance with the revised notes for coding to the undetermined intent categories. At the time that the ABS ceases processing, each coroners record on the NCIS will have a status of 'open' or 'closed'. The NCIS case status impacts on how deaths are coded with regard to suicides. With the introduction of the revisions process for all deaths registered from 1 January 2007, additional information received by the ABS may lead to a more specific cause of death code being assigned. Below is a summary of the suicide coding process used by the ABS.
Undetermined intent (Y10-Y34, Y87.2)
84 Due to changes in coding rules for ICD-10 in 2007, processing of data up to and including the 2006 reference year assigned a finding of 'Undetermined intent' only where this was the official coronial finding. Other deaths where either intent was 'not known' or 'blank' on the NCIS record, were coded with an intent of 'accidental'. From 2007, a death is coded to an 'Undetermined intent' code where the NCIS intent field is: 'could not be determined'; 'unlikely to be known'; or 'blank'. This change in coding practice has resulted in a significant increase in deaths allocated to these codes from 2007 onwards. However, it is important to note that it is expected that the number of deaths attributed to 'Undetermined intent' codes will decrease as revisions of preliminary data are undertaken, see Explanatory Notes 28-32.
CONFIDENTIALISATION OF DATA
85 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.
EFFECTS OF ROUNDING
86 Where figures have been rounded, discrepancies may occur between totals and sums of the component items.
87 ABS products and publications are available free of charge from the ABS website. Click on Statistics to gain access to the full range of ABS statistical and reference information. For details on products scheduled for release in the coming week, click on the Future Releases link on the ABS homepage.
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