3303.0 - Causes of Death, Australia, 2018 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 25/09/2019   
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Updates to Iris coding software: Implementing WHO updates and improvements in coding processes

Since 2014 the national Causes of Death dataset has been coded using Iris, a software program which automates the assignment of codes from the International Classification of Diseases 10th Revision (ICD-10) to death records, and assists in the identification of an underlying cause of death. Iris is developed and maintained by the German Institute of Medical Documentation and Information (DIMDI), who produce regular software updates, as well as implement World Health Organization (WHO) updates to the ICD-10 that are embedded within the Iris system.

In order to recognise and statistically represent changing health trends and advances in medical science research, specialist committees within WHO meet annually to review and recommend updates to the ICD-10. Updates can be minor, consisting of spelling updates or small updates to medical terminology within existing codes, or they can be major, consisting of reclassification of medical conditions to different codes, updates to coding rules or the addition or deletion of codes. To maintain consistency in statistical outputs major changes are only implemented on 3 year cycles.

For the coding of 2018 cause of death data the ABS implemented a new version of Iris software (version 5.4.0) which incorporates a new underlying cause of death processing system called the Multicausal and Unicausal Selection Engine (MUSE). Like previous versions of Iris, MUSE assigns codes to medical terms on the Medical Certificate of Cause of Death (MCCD) and applies WHO coding rules to appropriately code and modify multiple causes of death and select an underlying cause of death. This version of Iris also incorporates the most recent major updates to the ICD-10 (2016 coding year updates). The implementation of MUSE, alongside the updates to the ICD-10, align the Australian mortality data up to date with international best practice. The ABS have also implemented extra validation processes with the implementation of MUSE to ensure maximum alignment with WHO guidelines and coding rules.

Key statistical measures need to be considered when interpreting time series data with administrative changes made to processing.
There are generally four ways in which output can change:
1. A true change in disease or external event.
2. Administrative changes such as changes to certification or events at point of registration.
3. Updates to the WHO ICD-10 classification, Volume 2 coding rules and application of decision tables.
4. Process changes, such as the implementation of new software or changes to local coding practice.
Understandably, the focus of health policy is on true changes in patterns of mortality. The ABS uses explanatory notes to highlight administrative and process changes to enable better interpretation of trends in data over time.

This technical note will provide an overview of software changes, WHO updates and local coding changes to assist users in interpretting changes in the 2018 dataset. The information focusses on factors influencing the selection of underlying causes of death, although the multiple cause dataset is also acknowledged as an integral tool in tracking changes over time.

Chapter I, Certain infectious and parasitic diseases (A00-B99)
Updates to WHO guidelines have resulted in changes to causes located in Chapter I, Certain infectious and parasitic diseases:
A40 Streptococcal sepsis - A41 Other sepsis: A common certification issue is the recording of an infection such as sepsis in Part 1 of a death certificate with no preceding cause, with chronic conditions listed on the same certificate in Part 2. Previously, when sepsis was certified in Part 1 of the MCCD and selected chronic conditions were reported in Part 2 of the MCCD, the selection rules did not provide a mechanism for the condition in Part 2 to be selected as the underlying cause. An update to selection rules now allows more chronic conditions, such as neoplasms coded to (C00-C80), in Part 2 to be selected as the underlying cause when sepsis appears in Part 1. In particular, this has resulted in an increase in deaths assigned to Chapter II Neoplasms and a subsequent decrease in the number of deaths assigned to A40-A41 as an underlying cause.
A90 Dengue fever [classical dengue] and A91 Dengue hemorrhagic fever: These codes are no longer valid for causes of death outputs. All deaths previously assigned to A90 or A91 will now be assigned to A97 Dengue
A97 Dengue: This is a new code and includes multiple fourth digit options for coding. A97 replaces deaths previously assigned to A90 and A91.
B94 Sequelae of other and unspecified infectious and parasitic disease: Previously, if an infectious disease was reported with a duration of greater than one year, the sequelae code was assigned (B94). The processing of time intervals as they relate to infectious diseases now means that B94 is only assigned when late or residual effects of the infection are reported. This has resulted in a decrease in deaths assigned to B94.

Chapter II, Neoplasms (C00-D48)
Updates to WHO guidelines and ABS coding practices have resulted in an increase in deaths assigned to Chapter II Neoplasms.
There are now more causal relationships between acute conditions, including Bacterial sepsis (A40-A41), and Malignant neoplasms (C00-C80). Previously, when sepsis was mentioned in Part 1 of the MCCD and a malignant neoplasm was mentioned in Part 2, the sepsis would commonly be assigned as the underlying cause of death. In accordance with updated decision tables, there are now additional relationships by which neoplasms falling within C00-C80 can be selected as the underlying cause of death when mentioned in Part 2. This has resulted in an increase in deaths assigned to Chapter II Neoplasms and a subsequent decrease in the number of deaths assigned to A40-A41 as an underlying cause.

Chapter V, Mental and behavioural disorders (F00-F99)
F05 Delirium, not induced by alcohol and other psychoactive substances: Improvements in coding practices have resulted in a decrease in deaths coded to F05. When F05 is mentioned on the MCCD the decision tables do not provide a mechanism by which the causal condition of the delirium can be chosen as the underlying cause of death. The ABS mortality team have implemented improved coding and validation processes to ensure the causal condition of the delirium is now selected as the underlying cause. There is a notable decrease in deaths coded to delirium as an underlying cause of death as a result of this change.

Chapter VI, Diseases of the nervous system (G00-G99)
G23 Other degenerative diseases of basal ganglia: A new fourth-digit code, G233 Multiple system atrophy, cerebellar type [MSA-C], has been added to this category which has resulted in an increase in deaths assigned to G23. Most deaths assigned to G233 were previously coded to G903 Multiple system degeneration.
G83 Other paralytic syndromes: A new fourth-digit code, G835 Locked-in syndrome, has been added to this category. There was 1 death assigned to G835 in 2018.
G90 Disorders of autonomic nervous system: The fourth-digit code, G903 Multiple system degeneration has been removed as a valid code for cause of death coding. This has resulted in a decrease in deaths coded to G90. Causes previously coded to G903 are now coded to G238 Other specified degenerative diseases of basal ganglia.

Chapter IX, Diseases of the circulatory system (I00-I99)
I67 Other cerebrovascular diseases: Changes in coding processes have been made in relation to I67. Previously, if Chronic cerebrovascular disease was reported with a duration of greater than one year, the sequelae code was assigned (I69). Further, a note under I69 dictates that Chronic cerebrovascular disease is to be coded to I60-I67. Changes have been implemented resulting in the sequelae codes only being used if late or residual effects of the disease are reported. This change has resulted in an increase in deaths assigned to I67 and a subsequent decrease in deaths assigned to I69.

I69 Sequelae of cerebrovascular disease: Changes in coding processes have been made in relation to I69. Previously, if Chronic cerebrovascular disease was reported with a duration of greater than one year, the sequelae code was assigned (I69). Further, a note under I69 dictates that Chronic cerebrovascular disease is to be coded to I60-I67. Changes have been implemented resulting in the sequelae codes only being used if late or residual effects of the disease are reported. This change has resulted in a decrease in deaths assigned to I69 and a subsequent increase in deaths assigned to I67.

Chapter XII, Diseases of the skin and subcutaneous tissue (L00-L99)
L98 Other disorders of skin and subcutaneous tissue, not elsewhere classified: A new fourth-digit code, L987 Excessive and redundant skin and subcutaneous tissue, has been added to this category. No conditions were assigned to this code in 2018.

Chapter XIII, Diseases of the musculoskeletal system and connective tissue (M00-M99)
M19 Other arthrosis: A relationship between J18 Pneumonia, organism unspecified and M19 Other arthrosis has been removed in 2018. When J18 was reported in Part 1 of the MCCD and M19 in Part 2, previous relationships allowed M19 to be chosen as the underlying cause of death. The removal of this relationship no longer assigns M19 as the underlying cause in these cases. This has resulted in a decrease in deaths assigned to M19.

Chapter XV, Pregnancy, childbirth and puerperium (O00-O99)
O94 Sequelae of complication of pregnancy, childbirth and the puerperium: This is a new code in 2016. O94 is used for morbidity coding only and therefore has not affected output in this publication.

Chapter XVI, Certain conditions originating in the perinatal period (P00-P99)
P91 Other disturbances of cerebral status of newborn: This category has a new fourth-digit code, P917 Acquired hydrocephalus of newborn. No conditions were assigned to this code in 2018.

Chapter XX, External causes of morbidity and mortality (V01-Y98)
W26 Contact with other sharp object(s): There are now multiple fourth-digit options for W26. Previously, when a death occurred as a result of W26, there was no option to further specify the type of sharp object involved. ABS mortality coders are now required to choose from multiple fourth-digit options to further specify the death:
      • W260 Contact with knife, sword or dagger
      • W268 Contact with other sharp object(s), not elsewhere classified
      • W269 Contact with unspecified sharp object(s)
As a result, deaths previously assigned to W26 will now be assigned a fourth-digit during coding. No conditions were assigned to W260-W269 in 2018.