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3304.0 - Perinatal Deaths, Australia, 2007 Quality Declaration 
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 12/11/2009   
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EXPLANATORY NOTES


INTRODUCTION

1 This publication contains statistics on perinatal deaths for Australia, 1999 to 2007.

2 In order to complete a perinatal death registration, the death must be certified by either a doctor or by a coroner. In the case of perinatal deaths, the information supplied to the ABS is that contained within the Medical Certificate of Cause of Perinatal Death, which is prepared by the certifying medical practitioner or coroner.

3 Over 95% of perinatal deaths in 2007 were certified by a doctor. The remainder were typically reported to a coroner. Although there is variation in what constitutes a death that is reportable to a coroner across jurisdictions, 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; and
  • where the identity of the person who has died is unknown.

4 All coroner certified deaths registered after 1 January 2007 are subject to a revision process. This is a change from previous years where all ABS processing of perinatal deaths data for a particular reference period was finalised approximately 13 months after the end of the reference period. Where insufficient information was available to code a cause of death (e.g. a coroner certified death was yet to be finalised by the Coroner), less specific cause of death codes were assigned as required by the International Classification of Diseases (ICD) coding rules. The revision process will enable the use of additional information relating to coroner certified deaths as it becomes available over time resulting in increased specificity of the assigned codes. The ABS assigns cause of death codes to records using version 10 of the ICD (ICD-10).

5 Revised data for 2007 will be published on a year of registration basis in the 2008 Perinatal deaths publication, due to be released in March 2010, and again in the publication relating to the 2009 collection due for release in 2011. Revisions will only impact on coroner certified deaths, as further information becomes available to the ABS about the causes of these deaths.

6 In prior years, statistics on perinatal deaths have been included in the Causes of Death, Australia publication (cat. no. 3303.0). From the 2007 reference year onward, this data will be published as a separate publication, Perinatal Deaths, Australia (cat.no. 3304.0).

7 The data presented in this publication are also included in a series of spreadsheets that are available on the ABS website. Any references to tables in the Explanatory Notes also refer to these spreadsheets.

8 A Glossary is also provided detailing definitions of terminology used.


SCOPE AND COVERAGE

9 The statistics in this publication relate to the number of perinatal deaths registered, not those which actually occurred, in the years shown.


Scope of perinatal deaths statistics

10 The ABS perinatal deaths collection includes all perinatal 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 perinatal deaths statistics.

11 The scope of the perinatal death statistics includes all fetal deaths (at least 20 weeks gestation or at least 400 grams birth weight) and neonatal deaths (all live born babies who die within 28 days of birth, regardless of gestation or weight) which are:
  • deaths being registered for the first time;
  • deaths in Australia of temporary visitors to Australia;
  • deaths occurring within Australian Territorial waters;
  • deaths occurring in Australian Antarctic Territories or other external territories (excluding Norfolk Island);
  • deaths occurring in transit (i.e. on ships or planes) if registered in the State of "next port of call";
  • deaths that occurred in earlier reference periods that have not been previously registered (late registrations).

12 The scope of the perinatal deaths collection excludes:
  • repatriation of human remains where the death occurred overseas;
  • deaths occurring on Norfolk Island.

13 Fetal deaths are registered only as a death. Neonatal deaths are registered first as a birth and then a death.

14 Perinatal deaths data from 1999 - 2005 were processed in such a way that it was possible for registrations not to be recorded at all within the total historical record of all deaths which have occurred. The scope for registered perinatal deaths during these years was:
  • All perinatal deaths registered in Australia for the reference year, two years prior to the current year and the first quarter of the subsequent year

15 Under this rule, it was possible for a perinatal death registration to not be recorded in the collection if it had been registered more than two years before the record was received by the ABS. The scope was changed from the 2006 reference year to ensure all registrations are included in ABS collections. The new perinatal death scope rules are:
  • all perinatal deaths registered in Australia for the reference year and are received by the ABS by the end of the March quarter of the subsequent year; and
  • perinatal deaths registered prior to the reference year but not previously received from the Registrar nor included in any statistics reported for an earlier period.

16 As an example, records received by the ABS during the March quarter of 2008 which were initially registered in 2007 or prior (but not forwarded to the ABS until 2008) are assigned to the 2007 reference year. Any registrations relating to 2007 which are received by the ABS after the end of the March quarter are assigned to the 2008 reference year.

17 For 1996 and previous editions of this publication, data relating to perinatal deaths were based upon the World Health Organization (WHO) recommended definition for compiling national perinatal statistics. The WHO definition of perinatal deaths included infants and fetuses weighing at least 500 grams or having a gestational age of 22 weeks or body length of 25 centimetres crown-heel. A summary table based on the WHO definition of perinatal deaths (infants and fetuses weighing at least 500 grams or having a gestational age of 22 weeks) is included in this issue (see Datacube Table 4.1 Fetal, Neonatal, and Perinatal Deaths by International Standards, 22 weeks or 500 grams, 1999-2007).


Review of scope of perinatal deaths statistics

18 In 2008, the ABS completed a review which compared the various definitions and calculation methods adopted by a range of ABS collections and key non-ABS statistical collections, as they relate to perinatal, neonatal, fetal and infant deaths. It was intended that the review identify any inconsistencies between perinatal statistical definitions and interpretation used by ABS collections and those used by key non-ABS collections. ABS concepts and definitions were compared with those applied by the United Nations (UN), the World Health Organisation (WHO), the Australian Institute of Health and Welfare (AIHW), including the National Perinatal Statistics Unit (NPSU) and between ABS collections.

19 As a result of the ABS review a number of issues were identified with some of the concepts and definitions between ABS and key non-ABS statistical collections including:
  • Whilst the ABS had defined fetal deaths as 'a death of 20 or more completed weeks of gestation or of 400 grams or more birth weight', in practise, fetal death counts had been determined by identifying deaths ‘of 20 or more completed weeks of gestation and of 400 grams or more birth weight’. Adopting this practice had restricted the identification of some fetal deaths.
  • A gestation/birth weight criteria was being used for the determination of an in-scope live birth (gestational period (20wks) and birth weight (400gms)). The UN/WHO and AIHW/NPSU definitions do not apply any gestation/birth weight criteria to the determination of live births. This inclusion had an impact on all "denominators" used in the calculation of perinatal statistics mortality rates i.e. the denominator would exclude some records. Whilst in practice there may be little change in the resulting data from a change in definition (i.e. the likelihood of any baby being live born earlier than 20 weeks gestation or 400 grams birth weight is highly unlikely) a new definition removing the gestation/birth weight criteria has been introduced. This is now congruent with the UN/WHO and AIHW/NPSU definitions and will allow future advances in medical science regarding survivability of pre-term babies.
  • A gestation/birth weight criteria was being applied for the determination of an in-scope neonatal death. This definition excluded some neonatal deaths through the application of the 20 weeks/400 grams criteria and was in conflict with the definition for neonatal deaths.

20 As a result of the findings above, new wording and expanded definitions have been applied to the perinatals collection to achieve consistency between ABS collections and other non ABS collections. It is due to the revision of scope definitions for perinatal death counts and calculation of rates that data from 1999 to 2006 has been re-published in this edition of this publication. The new scope definitions will be applied to all perinatal data in the future. The table below shows the impact of the revised scope on the data.

Table 1.1. Comparison , New ABS Scope Perinatals and Old ABS Scope Perinatals (published) - Australia - 1999-2007(a)

New Scope(b)
Old Scope(c)
Difference
Fetal death
Neonatal death
Fetal death
Neonatal death
Fetal death
Neonatal death

1999
1 647
953
1 284
849
363
104
2000
1 668
866
1 303
773
365
93
2001
1 655
916
1 290
802
365
114
2002
1 618
857
1 240
779
378
78
2003
1 638
842
1 288
732
350
110
2004
1 725
816
1 347
701
378
115
2005
1 837
932
1 411
802
426
130
2006
1 595
864
1 394
864
201
-
2007
1 676
856
. .
. .
. .
. .

. . not applicable
- nil or rounded to zero (including null cells)
(a) 2007 data is preliminary and will be subject to a revision process. See Explanatory Notes 4-5 for further information.
(b) New scope includes all perinatal deaths where gestation is at least 20 weeks or birth weight is at least 400g . See Glossary for further information.
(c) Old scope includes all perinatal deaths where birth weight is at least 400g and gestation is at least 20 weeks.
Note: 'not stated' , 'not applicable' or 'unknown' are included in scope.



Coverage of Perinatal Statistics

21 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 and the subsequent delays in the provision of that information to the ABS, not all deaths are registered in the year that they occur. This ideal is unlikely to be met under the current legislation and registration business processes. Therefore, the occurrence event is approximated by 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 the Registrar (processing or data transfer lags). In effect there are 3 dates attributable to each death registration:
  • the date of occurrence (of the death),
  • the date of registration or inclusion on the State/Territory register, and
  • the month in which the registered event is lodged with the ABS.

22 Approximately 10-13% of perinatal deaths occurring in one year are not registered until the following year or later. For example, 13% of perinatal deaths occurring in 2006 were registered in 2007. These are included with the count of registered perinatal deaths published for that year (2007).

23 Despite the legislated requirements, deaths can be registered some time after the date of occurrence. This can be due to delays with the applicant, which are largely beyond the control of ABS and the Registry, or due to registry processing irregularities and backlogs.


CLASSIFICATIONS

Socio-Demographic Classifications

24 A range of socio-demographic data is available from the perinatal deaths collection. Standard classifications used in the presentation of perinatal deaths statistics include sex and Indigenous status. Statistical standards for social and demographic variables have been developed by the ABS.


Indigenous Status

25 The term Indigenous is used to refer to Aboriginal and Torres Strait Islander Australians. Those who are identified as being of Aboriginal and/or Torres Strait Islander origin through the death registration process are classified as Indigenous persons.

26 For further information about Indigenous Status refer to Standards for Statistics on Cultural and Language Diversity, 1999 (cat. no. 1289.0)


Geographic Classifications

Australian Standard Geographical Classification (ASGC)

27 The ASGC is a 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. Perinatal deaths statistics are coded to SLA and can be produced for aggregates of these, for example, Statistical Division, Statistical Sub-Division and State.

28 For further information about the ASGC refer to Australian Standard Geographical Classification (ASGC), Jul 2006 (cat. no. 1216.0)


Health Classifications

International Classification of Diseases (ICD)

29 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 perinatal death statistics

30 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:
  • epidemic diseases;
  • constitutional or general diseases;
  • local diseases arranged by site;
  • developmental diseases; and
  • injuries.

31 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 or a congenital condition such as spina bifida is grouped with congenital conditions.

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

33 The ICD 10th Revision is also available online.


DATA SOURCES

34 The registration of perinatal deaths is the responsibility of the individual state and territory Registrars of Births, Deaths and Marriages. There exists a national legislative requirement that all deaths be registered. The legislation varies from state to state and the time period allowed to submit an application to register a death also varies and may depend on the relationship of the applicant to the deceased.

35 As part of the registration process, information about the causes 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. This information is provided to the Australian Bureau of Statistics (ABS) by individual Registrars for coding and compilation into aggregate statistics shown in this publication. In addition, the ABS supplements this data with information from the National Coroners Information Service (NCIS). Further information regarding causes of death data sources can be obtained from:

MORTALITY CODING

36 The tenth revision of the International Classification of Diseases (ICD-10) was adopted for Australian use for perinatal deaths registered from 1 January 1999.

37 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.

38 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.

39 For perinatal deaths, both the main condition in the fetus/infant, and the main condition in the mother are coded to the full four-digit level of the tenth revision of ICD. Causes selected for publication in this issue are those categories which were responsible for a significant proportion of perinatal deaths.

40 There is some variability over time across a range of the perinatal death categories and where the numbers are small, caution should be applied in drawing inferences about change over time.


Updates to ICD-10

41 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.

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


Automated coding

43 The ABS implemented a new version of the automated cause of death coding software (Medical Mortality Data System(MMDS)) for 2006 data. This version has also been used for coding of 2007 data. The MMDS coding software incorporates coding algorithms to ensure that updates to ICD-10 are implemented in the production of the statistics


COMPARABILITY OF STATISTICS OVER TIME

44 All data presented in this publication have had new scope rules applied for perinatal deaths and are therefore consistent and comparable across the years 1999 to 2007. (See Explanatory Notes 18-20). Comparability of perinatal statistics over time is affected by a number of factors. These include issues relating to the collection, classification and processing of the data. In the late 1990s, there were two major changes within Australia, namely, the introduction of ICD-10 for classifying deaths registered from 1 January 1999; and the introduction of the Automated Coding System (ACS) for processing deaths registered from 1 January 1997. See Appendix 1: Comparability of Statistics over Time in Causes of Death, Australia, 2007 cat. no. 3303.0 for further information.


STATE AND TERRITORY DATA

45 Perinatal deaths 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 are included in the state/territory in which their death was registered.

46 Statistics compiled on a state or territory of registration basis are available on request.


DATA QUALITY

47 In compiling perinatal deaths statistics, the ABS employs a variety of measures to improve quality, which include:
  • providing certifiers with certification booklets for guidance in reporting causes of death on medical certificates. See Information Paper: Certification of Death (cat. no. 1205.0.55.001);
  • seeking detailed information from the National Coroners Information Service (NCIS); and
  • editing checks at the individual record and aggregate levels.

48 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.

49 Further detail on issues regarding deaths certified by a Coroner can be found in Technical Note: Coroner Certified Deaths.


Indigenous deaths

50 While it is considered likely that most perinatal deaths of Indigenous Australians are registered, a proportion of these deaths are not identified as Indigenous by the family, health worker or funeral director during the death registration process. That is, whilst data is provided to the ABS for the Indigenous status question for 99% of all deaths, there are concerns regarding the accuracy of the data. The Indigenous status question is not always being directly asked of relatives and friends of the deceased by the funeral director.

51 This publication includes the number of registered Indigenous perinatal deaths for Australia. However, because of the data quality issues outlined below, more detailed breakdowns of Indigenous deaths are provided only for New South Wales, Queensland, South Australia, Western Australia and the Northern Territory. Victoria, Tasmania, and the Australian Capital Territory are included in the Australia total.

52 The likelihood that a person will identify, or be identified, as Indigenous on a specific form is known as their propensity to identify as Indigenous. Propensity to identify as Indigenous can be thought of as the proportion of the total, unknown, number of Indigenous people who identify as such on a specific form.

53 Propensity to identify as Indigenous is determined by a range of factors, including how the information is collected; who completes the form; the perception of how the information will be used; education programs about identifying as Indigenous; and cultural issues associated with identifying as Indigenous.

54 A number of deaths occur each year where Indigenous status is not stated on the death registration form. Despite the relatively low number of deaths with unidentified Indigenous status, it is likely that some of these are Indigenous deaths, contributing to the overall under coverage of Indigenous deaths.

55 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.

56 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.


SPECIFIC ISSUES FOR 2007 DATA

57 A number of issues should be taken into account by users when analysing the 2006 and 2007 perinatal deaths data.

58 Across the states and territories the degree to which different data items are available for 2006 and 2007 varied from full provision of all data items, to full provision of some of the data items, to no provision of the key data items (i.e., birth weight and/or gestation period). As a result of these limitations on the data, the publication and data cubes in this issue contain less disaggregated data than was released prior to 2006.

59 2007 perinatal deaths data is subject to revision. Revised data for 2007 will be published on a year of registration basis in the 2008 Perinatal deaths publication, due to be released in March 2010, and again in the publication relating to the 2009 collection due for release in 2011. See Explanatory Notes 4 and 5 above for further information.


Unspecified Causes of Mortality

60 The introduction of a new version of the MMDS software in 2006 has corrected a previous coding error. Prior to 2006, deaths due to natural causes with no further information were coded to Unattended Death (R98). From 2006, these records are now coded to Other ill-defined and unspecified causes of mortality (R99).

61 Information regarding coroner certified deaths prior to 2006 was obtained by ABS staff visiting coronial offices and investigating case files in order to determine causes of death. In 2003, in order to make most effective and efficient use of ABS resources, the National Coronial Information System (NCIS) was progressively introduced as the main source of information on coroner certified deaths, however visits by ABS staff continued to be made in a number of jurisdictions. From 2006, the NCIS has been the only source of data used by the ABS for coroner certified deaths. This has resulted in an increase in the number of deaths assigned to Other ill-defined and unspecified causes of mortality (R99) due to the unavailability of information on the NCIS, particularly for New South Wales and Queensland. For further information see Coroner Certified Deaths: Technical Note. It is important to note that the number of deaths attributed to Other ill-defined and unspecified causes of mortality for 2007 is expected to decrease as data is revised. See Explanatory Notes 4 and 5.


BIRTHS DATA

62 Appendix 1 provides details of the number of live births registered which have been used to calculate the fetal, neonatal and perinatal death rates shown in this publication. Appendix 1 also provides data on fetal deaths used in the calculation of fetal and perinatal death rates. These also enable further rates to be calculated.


CONFIDENTIALISATION OF DATA

63 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 effected by confidentialisation.


EFFECTS OF ROUNDING

64 Where figures have been rounded, discrepancies may occur between totals and sums of the component items.


ACKNOWLEDGEMENT

65 This publication draws extensively on information provided freely by the state and territory Registrars of Births, Deaths and Marriages, and the Victorian Institute of Forensic Medicine who manage the National Coroners Information System (NCIS). Their continued cooperation is very much appreciated: without it, the wide range of vitals statistics published by the ABS would not be available.


RELATED PRODUCTS

66 Other ABS publications which may be of interest are outlined below. Please note, older publications may no longer be available through ABS bookshops but are available through ABS libraries. All publications released from 1998 onwards are available on the ABS website <http://www.abs.gov.au>
67 ABS products and publications are available free of charge from the ABS website <http://www.abs.gov.au>. 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.


ADDITIONAL STATISTICS AVAILABLE

68 As well as the statistics included in this and related products, additional information is available from the ABS web site at <http://www.abs.gov.au> by accessing the topics listed at Themes>People. The ABS may also have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070 or by sending an email to client.services@abs.gov.au.


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