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TECHNICAL NOTE 1 ABS IMPLEMENTATION OF IRIS SOFTWARE: UNDERSTANDING CODING AND PROCESS IMPROVEMENTS


In 2014 the Australian Bureau of Statistics (ABS) implemented Iris, a software program which automatically assigns codes from the International Classification of Diseases 10^th Revision (ICD-10) to death records, and assists in the identification of an underlying cause of death. Iris has replaced the Mortality Medical Data System (MMDS). Iris has been used in the processing of the full 2013 causes of death dataset.

The implementation of Iris has enabled the ABS to apply a series of ICD-10 updates, bringing the coding of Australian mortality data up to date with international best practice. A review of coding practices has also been undertaken, focussing on maximising compliance with coding rules detailed in Volume 2 of ICD-10.

The move to Iris, the application of ICD-10 updates and the review of coding practices all have the potential to impact statistical outputs. It should be noted that updates applied to the ICD-10 are regulated by the World Health Organisation (WHO) and are adopted only where they enhance accuracy or reflect improved medical understanding. To that end the changes in this issue will improve the quality of the Australian mortality dataset.

The purpose of this Technical Note is to provide a chapter by chapter summary of changes that have occurred as a result of software and coding updates. This technical note provides a resource for data users to understand where changes have occurred within the dataset and the impact of those changes moving forward.


CONTENTS

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, coding rules and application.
4. Process changes, such as the implementation of Iris or changes to local coding practice.

· A04 Other bacterial intestinal infection: An increased number of causal relationships now exist with A04 Other bacterial intestinal infection. This change has led to a decrease in deaths assigned to A04 as an underlying cause.

· A09 Other gastroenteritis and colitis of infectious and unspecified origin. Previously coding notes stated that in countries such as Australia, unspecified gastroenteritis and colitis should be assumed to be noninfectious. This note has been deleted, and as such the assumption is now that the disease is infectious where not otherwise stated. The result is an increase in deaths assigned the code A09 as an underlying cause and a corresponding decrease in deaths assigned to K52 Other noninfective gastroenteritis and colitis.

· A16 Respiratory tuberculosis, not confirmed bacteriologically or histologically; B18 Chronic Viral Hepatitis; B90 Sequelae of tuberculosis; B94 Sequelae of other and unspecified infectious and parasitic diseases: A change in coding practice has been made in relation to tuberculosis and hepatitis deaths. Previously, if tuberculosis or hepatitis was reported with a duration of greater than one year, the sequelae code was assigned. Changes have been implemented resulting in the sequelae codes only being used if late or residual effects of the disease are reported. The result is an increase in deaths assigned an underlying cause of A16 and B18 and a decrease in deaths assigned to B90 and B94.

· B98, Other specified infectious agents as the cause of diseases classified to other chapters: This is a new code for output. It is included in the block B95-B98 Bacterial, viral and other infectious agents. It is currently not to be used for primary coding and therefore, no deaths are assigned an underlying cause of B98.

· C80 Malignant neoplasm, without specification of site: A coding change has been applied in relation to metastatic cancer to ensure that a primary cancer code of unspecified site (C809) is automatically assigned as the underlying cause of death. This change applies to the sites listed in Table 3 Common sites of metastases in Volume 2 of the ICD-10. For example, metastatic brain cancer would be coded as C793, C809. Previously if a cancer on the secondary list was certified as metastatic, but was the only cancer listed on the certificate, the primary cancer code associated with the specified site was assigned. This change will result in an increase in deaths assigned to C80 as an underlying cause and increases across secondary cancers of specified sites as associated causes of death.

· C81-C96 Malignant neoplasms, stated or presumed to be primary, of lymphoid, haematopoietic and related tissue:
o C81-C85: There have been changes to code titles within this block to reflect appearance, genetic features and chemistry. Code title previously only reflected the appearance of the cancer.
o C83 Non-follicular lymphoma; C85 Other and unspecified types of non-Hodgkin lymphoma: Previously the term "diffuse large B cell lymphoma" was coded to C85. This coding practice was reassessed with the introduction of the new code titles for the block C81-C96, and the term is now coded to C83. This will result in an increase in deaths assigned an underlying cause of C83 and a decrease in deaths assigned to C85.
o C86 Other specified types of T/NK-cell lymphoma: This is a new code within the code block C81-C96 that has been introduced to capture an expanded group of T/NK lymphomas not classified in C84 Mature T/NK-cell lymphomas.
o C93 Monocytic leukaemia: The term Monocytic leukaemia was previously coded to C92 Myeloid leukaemia (using MMDS software). Iris more correctly assigns the code C93 Monocytic leukaemia. The result is a decrease in deaths assigned an underlying cause of C92 and a corresponding increase in deaths assigned an underlying cause of C93.


· C97 Malignant neoplasms of independent (primary) multiple sites: This code is now invalid as an underlying cause of death. Deaths previously assigned the code C97 have been reassigned to other malignant cancer codes (C00-C96, D45) in accordance with updated decision tables.

· D45 Polycythaemia vera: Polycythaemia vera has been reclassified as a malignant neoplasm in the International Classification of Diseases for Oncology (ICD-O-3). Previously this condition was considered a neoplasm of uncertain or unknown behaviour. This change has now been applied in the ICD-10. Polycythaemia vera remains in the block D37-D48 Neoplasms of uncertain or unknown behaviour despite being recognised as a malignant neoplasm. As such, for analytical purposes malignant neoplasms would be best represented as C00-C97, D45.

· D64 Other anaemias: A causal link between D64 Other anaemias and I50 Heart failure has been established. As such, D64 can now be assigned as the underlying cause of death when sequenced with I50 on a death certificate. This has resulted in an increase in deaths assigned an underlying cause of D64.

· E11 Non-insulin-dependent diabetes mellitus (Type 2 Diabetes): There are now a greater number of conditions that link to Type 2 Diabetes to form a combination code for underlying cause of death output. Combination codes occur when two or more conditions on the death certificate link and combine to form one code. A key example for Type 2 Diabetes is that an increased number of kidney disease codes (e.g. I12 Hypertensive renal disease, N00-N29 Renal disorders) are linking with E11, to output as E11.2 Non-insulin-dependent diabetes mellitus with renal complications. These new linkages have resulted in an increased number of deaths assigned an underlying cause of E11.2.

· E86 Volume depletion: A coding change was implemented regarding the reporting of refusal of food or fluid in natural deaths of elderly persons. Previously when this term appeared on a death certificate it was coded to E86 Volume depletion. It is now coded to R63 Symptoms and signs concerning food and fluid intake. This change has resulted in a decrease in deaths assigned an underlying cause of E86. As R63 is considered an ill-defined condition it is therefore less likely to be assigned as an underlying cause of death.

· F01 Vascular dementia: A coding change has been made regarding the causal relationship between dementia and cerebrovascular diseases. When F03 Unspecified dementia appears as "due to" I60-I69 Cerebrovascular diseases, coding rules combine the two codes into one. For example F03 Unspecified Dementia due to I64 Stroke, not specified as haemorrhage or infarction will combine to become F01 Vascular dementia. This coding change necessitates a causal relationship to be established for the two codes to be combined, whereas previously this causal relationship was not required. This change will result in a decrease in deaths assigned an underlying cause of F01 and a corresponding increase deaths assigned to F03.

· F03 Unspecified dementia: J690 Pneumonitis due to food and vomit now has a causal relationship with an extended number of conditions including F03 Unspecified dementia. This has resulted in an increase in deaths assigned to F03 Unspecified dementia as an underlying cause and a corresponding decrease to J690 Pneumonitis due to food and vomit. In conjunction with this there has been a change to the coding of the term "chest infection" (see Chapter 10 for further detail), that has resulted in an increase to deaths assigned to F03 Unspecified dementia as an underlying cause.

· F07 Personality and behavioural disorders due to brain disease, damage and dysfunction: Coding practice was updated to assign the code G31 Other degenerative diseases of nervous system, not elsewhere classified to the term “frontotemporal dementia”. Previously this term was coded to F07. The result is a decrease in deaths assigned an underlying cause of F07 and an increase in deaths assigned a codes of G31.

· F10-F19 Mental and behavioural disorders due to psychoactive substance use:
o F10.2, F11.2….F19.2 Mental and behavioural disorders due to psychoactive substance use, dependence syndrome: A coding update has been implemented regarding dependence syndromes as an underlying cause of death. Previously, if a death was due to an accidental drug overdose and the deceased suffered a current addiction to that drug, the addiction was reported as the underlying cause of death (e.g. F112 Mental and behavioural disorders due to use of opioids, dependence syndrome). Under new rules, the drug overdose is captured as the underlying cause of death and the addiction is retained as an associated cause of death. The result is an increase to the code block X40-X49 Accidental poisoning by and exposure to noxious substances and decreases to the number of deaths assigned to the code block F10-F19. The code assigned to the addiction will be retained as an associated cause of death and can be accessed in the multiple cause of death datacube.
o F17 Mental and behavioural disorders due to use of tobacco: A coding update was made whereby F17 is not assigned as the underlying cause of death if the resultant physical condition is known. The result is a reduction in F17 as an underlying cause of death. F17 will still be retained as an associated cause of death and can be accessed in the multiple cause datacube.

· G14 Postpolio syndrome: This is a new code. It is included in the block G10-G14 Systemic atrophies primarily affecting the central nervous system.

· G20 Parkinson disease: J690 Pneumonitis due to food and vomit now has a causal relationship with an extended number of conditions including G20 Parkinson disease. This has resulted in an increase in the number of deaths assigned an underlying cause of G20 and a corresponding decrease in deaths assigned to J690. In conjunction with this there has been a change to the coding of the term “chest infection” (see Chapter 10 for further detail), that has resulted in an increase to deaths assigned to G20 as an underlying cause.

· G30 Alzheimer disease: J690 Pneumonitis due to food and vomit now has a causal relationship with an extended number of conditions including G30 Alzheimer disease. This has resulted in an increase in the number of deaths assigned an underlying cause of G30 and a corresponding decrease in deaths coded to J690. In conjunction with this there has been a change to the coding of the term “chest infection” (see Chapter 10 for further detail), that has resulted in an increase to deaths assigned to G30 as an underlying cause.

· G40 Epilepsy: Coding practices have been updated regarding the selection of G40 Epilepsy as the underlying cause of death when it is reported with an external cause. Previously, if G40 Epilepsy was reported in Part 2 of the death certificate and an external cause of death listed in Part 1, G40 was assigned as the underlying cause of death. G40 Epilepsy must now be in a "due to" position on the death certificate or stated by the coroner to have caused the external event for it to be assigned as the underlying cause of death. The result is a decrease in the number of deaths assigned an underlying cause of G40. G40 Epilepsy will be retained as an associated cause of death and can be seen in the multiple cause dataset.

· G82 Paraplegia and tetraplegia: J690 Pneumonitis due to food and vomit now has a causal relationship with an extended number of conditions including G82 Paraplegia and tetraplegia. This has resulted in an increase in the number of deaths assigned an underlying cause of G82 and a corresponding decrease to deaths assigned to J690.

· I10-I15 Hypertensive diseases:
o I11 Hypertensive heart diseases: Combination code rules have been updated regarding the assigning of the underlying cause for deaths where both I50 Heart failure and I10 Essential (primary) hypertension appear on a death certificate together. Previously, hypertension and heart failure would only combine to form I11 Hypertensive heart disease if hypertension was certified as "due to" heart failure. The causal relationship has been updated, resulting in the two conditions combining to form I11 regardless of sequential placement on the death certificate. Deaths assigned an underlying cause of I11 have increased as a result of this update.
o I12 Hypertensive renal disease; I13 Hypertensive heart and renal disease: Due to the changes noted above for I11 Hypertensive heart disease, there is a flow on effect to deaths involving heart failure, hypertension and renal failure. Deaths which involve hypertension, heart failure and renal failure now combine to result in the code I13. Previously, unless certified in an appropriate sequence these deaths were certified to I12. The result is an increase in deaths assigned an underlying cause of I13 and a corresponding decrease in deaths assigned to I12. In conjunction with this update, I12 Hypertensive renal disease now has a causal relationship with E11 Non-insulin- dependent diabetes mellitus. The result of this is that I12 and E11 now combine to output as E11.2 Non-insulin-dependent diabetes mellitus with renal complications. This has resulted in a decrease in I12 as an underlying cause of death and a corresponding increase in E11.


· I63 Cerebral infarction: Previously the term "ischaemic stroke" was coded to I64 Stroke, not specified as haemorrhage or infarction. Coding improvements now see this term coded to I63 Cerebral infarction, resulting in an increase in deaths assigned to I63 as an underlying cause.

· I84 Haemorrhoids: This is now an invalid code. Haemorrhoids are now coded to K64 Haemorrhoids and perianal venal thrombosis.

· J44 Other chronic obstructive pulmonary disease (COPD): Updates to causal relationships were made regarding the selection of J44 as an underlying cause of death. J44 COPD is now considered to cause an extended range of Pneumonias. In conjunction with this, a coding change to "chest infections" has resulted in a higher number of records coded to J44 as an underlying cause of death.

· J69 Pneumonitis due to solids and liquids: Conditions that have causal relationships with J69 have been expanded resulting in a decrease in deaths assigned to J69 as an underlying cause of death.

· J98 Other respiratory disorders: The term "chest infection" was previously coded to J98 Other respiratory disorders. This term is now coded to J22 Unspecified acute lower respiratory infection. As a result the number of deaths assigned to an underlying cause of J98 has decreased. The range of conditions which have causal relationships with J22 is greater than those associated with J98. Therefore J22 may be more commonly coded as an associated cause, but other conditions are likely to be coded as the underlying cause of death.

· K52 Other noninfective gastroenteritis and colitis: An inclusion note change for A09 Other gastroenteritis and colitis of infectious and unspecified origin now means that gastroenteritis and colitis must be specified as noninfective to be coded to K52. The result is a decrease in K52 as an underlying cause of death and a corresponding increase in A09.

· K64 Haemorrhoids and perianal venous thrombosis: This is a new code for output. It has been added to the code block K55-K64 Other diseases of intestines. It replaces the code I84 Haemorrhoids, which was located in Chapter 9, Diseases of the circulatory system.

· K70-K77 Diseases of liver: I61 Intracerebral infarction can now be "due to" any liver disease resulting in an increase to deaths assigned to the code block K70-K77 as an underlying cause. In conjunction with this, K70-K77 Diseases of liver now have a causal relationship with codes from the block A00-A09 Intestinal infectious diseases, resulting in an increased number of deaths assigned to K70-K77 as an underlying cause.

· M19 Other arthrosis: A causal link between M19 Other arthrosis and J18 Pneumonia, organism unspecified has been established. As such, M19 can now be assigned as the underlying cause of death when sequenced with J18 on a death certificate. This has resulted in an increase in deaths assigned an underlying cause of M19 Other arthrosis.

· N17-N19 Renal failure: There has been an increase in the number of conditions that have a causal relationship with renal failure. As a result, fewer deaths have been assigned to the code block N17-N19 as an underlying cause of death. Of note, E11 Non-insulin-dependent diabetes mellitus now combines with renal failure to form the code E11.2 Non-insulin- dependent diabetes mellitus with renal complications.
o N18 Chronic kidney disease: The title of code N18 has changed from Chronic renal failure to Chronic kidney disease. With the title update a coding change has occurred. Previously the term “Chronic kidney disease” was coded to N03 Chronic nephritic syndrome. It is now coded to N18 Chronic kidney disease. Consequently, deaths assigned to N03 as an underlying cause have decreased.


· N28 Other disorders of kidney and ureter classified elsewhere: The number of conditions reporting a causal relationship with N28 Other disorders of kidney and ureter classified elsewhere have been extended, resulting in a decrease to the number of deaths assigned to N28 as an underlying cause.

· Q90 Down syndrome: A causal relationship now exists between F03 Unspecified dementia and Q90 Down syndrome when the two conditions appear sequentially on a death certificate. The result is an increase in deaths assigned to Q90 as an underlying cause.

· Perinatal deaths: Many perinatal deaths are assigned codes from Chapter 17. See Changes to Perinatal Death Coding when interpreting output for perinatal deaths.

· R65 Systemic Inflammatory Response Syndrome (SIRS): This is a new code. It is located in the block R50-R69 General symptoms and signs.

· R99 Other ill-defined and unspecified causes of mortality: Coding changes have been made to deaths of unspecified or unknown natural causes. In some cases, where a Coroner made a finding of “due to unknown natural causes” but listed existing natural disorder/s in the Autopsy or Summary of findings, these existing natural disorder/s were assigned as the underlying cause of death. The underlying cause of death is now assigned to R99 unless the Coroner’s report is explicit that the natural conditions were detrimentally involved in the train of morbid events leading to death. The result is an increase in deaths assigned to R99 as an underlying cause.

· V01-V09 Pedestrian injured in transport accident: Updates regarding the definitional scope for pedestrian deaths have been applied. Previously deaths involving vehicle maintenance and specified industrial accidents were coded to the block V01-V09 Pedestrian injured in transport accident. These deaths are now assigned to the block W20-W49 Exposure to inanimate mechanical forces. Deaths assigned to V01-V09 as an underlying cause have decreased with a corresponding increase to deaths assigned to W20-W49.

· V50-V59 Occupant of pick-up truck or van injured in transport accident: A coding improvement has been applied regarding definitional scope for the block V50-V59. Previously vehicle accidents involving utility vehicles were coded to this block. Vehicle accidents involving utility vehicles are now assigned to the block V40-V49 Car occupant injured in transport accident. The result is a decrease in deaths assigned to the block V50-V59.

· W01 Fall on same level from slipping, tripping and stumbling; W19 Unspecified fall: Improvements have been applied to the coding of falls. Formerly, the term “mechanical fall” was coded to W01 Fall on same level from slipping, tripping and stumbling. This has been reviewed and mechanical falls are now coded to W01 only if the fall is specified as occurring on the same level. The result is a decrease in falls assigned an underlying cause of W01 and a corresponding increase in deaths assigned to W19.

· W78 Inhalation of gastric contents; W80 Inhalation and ingestion of other objects causing obstruction of respiratory tract: The set of conditions reporting a causal relationship with W78 and W80 has expanded, meaning that the number of deaths assigned to W78 and W80 have decreased as an underlying cause.

· X40-X49 Accidental poisoning by and exposure to noxious substances; X60-X69 Intentional self-harm by self-inflicted poisoning; Y10-Y19 Poisoning by and exposure to noxious substances, undetermined intent: Updates have been applied to the underlying cause of death for drug related deaths of all intents. Previously, when a death involved multiple substances, it was coded to a multiple drug overdose (X44, X64 or Y14 respectively depending on the intent of the death). Updates now direct a multiple drug overdose code to be assigned only if the death is explicitly stated by the certifier as being the result of multiple drugs. The underlying cause is now assigned to the main contributing or most dangerous drug. The remaining drugs involved in the death are recorded as poisoning codes and can be accessed in the multiple cause dataset. For example, if a person accidentally overdoses on heroin but also had cannabis and paracetamol in their system, the underlying cause of death would be coded to X42 Accidental poisoning by and exposure to narcotics and psychodysleptics, not elsewhere classified. Heroin, cannabis and paracetamol would be recorded as T401, T407 and T390 respectively. Under the former rules, the poisoning codes would remain the same, but the underlying cause of death would have been recorded as X44 Accidental poisoning by and exposure to other and unspecified drugs, medicaments and biological substances. The result of this coding change will be an increase in specified drug codes as underlying causes of death, across all intents.