TECHNICAL NOTE 2 CHANGES TO PERINATAL DEATH CODING
1 The Australian Bureau of Statistics introduced a program of improvements to its causes of death collection in 2014. This includes the introduction of a new software system for coding causes of death, implementation of updates to the International Classification of Diseases 10th Revision (ICD-10) and a review of coding practices. As part of this review changes have been made to the coding and tabulation of perinatal deaths.
2 In Australia, neonatal deaths (deaths that occur within 28 completed days of birth) are reported on the Medical Certificate of Cause of Perinatal Death (MCCPD). The review highlighted that there is no internationally supported rule base in the ICD-10 for assigning an underlying cause to deaths reported on the MCCPD. As a result, underlying cause has not be assigned to 2013 neonatal deaths.
3 The ABS understands the importance of fit for purpose information on causes of neonatal deaths and that this change may have implications for some data users. The ABS is actively working with the international community to seek a supported mechanism for deriving an underlying cause. In the interim, additional tables for 'main condition in infant' and 'main condition in mother' have been produced as part of this release.
CHANGES TO THE CODING PROCESS
4 When a stillbirth or neonatal death occurs in Australia, state and territory legislation ensures that a doctor or coroner completes a MCCPD. The MCCPD only allows certifiers to report a 'main condition in infant', 'main condition in mother' and other conditions. The MCCPD does not allow a certifier to provide a sequence which is required to identify an underlying cause of death. Deaths which occur 28 days of more after birth are reported on the Medical Certificate of Cause of Death (MCCD) which is specifically designed around providing a sequence for deriving an underlying cause.
5 Volume 2 of the ICD-10 provides guidelines for the production and tabulation of mortality data. Instructions in Volume 2 of the ICD-10 relating to use of the MCCPD note that where a single cause of death is required to be reported in tabulated outputs, the 'main condition in infant' should be used.
6 The ABS has previously derived and reported an underlying cause for neonatal deaths. The derivation of this underlying cause was based on rules developed by the ABS which assumed causal links between different conditions reported on the perinatal certificate. As this set of rules was not based on the ICD guidelines the decision was taken to cease this process while further investigations are conducted.
7 The coding rules used to determine the 'main condition in infant' and 'main condition in mother' for neonatal deaths and stillbirths have also been reviewed. Some adjustments have been made based upon the need to realign with international coding practices and overcome problems where certificates have been incorrectly completed. See pages 115-122 of the ICD-10 Instruction Manual for the international rules on certification and coding of perinatal deaths.
8 The ABS will work with key national stakeholders to understand specific reporting requirements for perinatal deaths. The ABS is also actively working with the World Health Organization Mortality Reference Group to determine a new supported process for assigning an underlying cause for deaths certified on the MCCPD.
CHANGES TO TIME SERIES DATA WITHIN UNDERLYING CAUSE OF DEATH TABLES
9 Information on neonatal deaths presented in tabulations up to 2012 are based upon the derived version of an underlying cause of death. Tabulations for the 2013 reference period still include neonatal deaths, but they are tabulated by 'main condition in infant' instead of a derived underlying cause.
10 As statistics relating to neonatal deaths in 2013 are presented on a different basis to those of earlier years, time series comparisons using the underlying cause tables are not possible.
11 Neonatal death are predominantly reported in Chapter 16 Certain conditions arising in the perinatal period. The changes in method of tabulation have led to a decrease in the number of deaths assigned codes in P00-P04: Fetus and newborn affected by maternal factors and by complications of pregnancy, labour and delivery and an increase in deaths assigned to the code P07: Disorders related to short gestation and low birth weight, not elsewhere classified.
12 To assist users with the transition from reporting an underlying cause to reporting 'main condition in infant' for neonatal deaths, an expanded range of data is provided in the datacube Perinatal deaths (Australia). This includes cross-tabulations between the fields 'main condition in infant' and 'main condition in mother'.
CHANGES TO TIME SERIES DATA FOR PERINATAL TABLES
13 Coding practices for perinatal deaths have been updated to align with international coding guidelines. These updates have a minor impact on the 'main condition in infant/fetus' and 'main condition in mother' fields within perinatal deaths datacube. The changes have no discernible impact on the time series data for neonatal deaths. However, for stillbirths the changes have resulted in a small increase in the number of records with a 'main condition in fetus' of P95: Fetal death of unspecified cause (952 in 2012 and 1,043 in 2013) and a decrease in records coded to P07: Disorders related to short gestation and low birth weight, not elsewhere classified (306 in 2012 and 138 in 2013).
14 There are some jurisdictions for which the ABS receives no causes of death information for stillbirths. For these jurisdictions, P95 is the only code able to be assigned for any stillbirth record.
15 Main condition in mother is not reported on all perinatal certificates. In previous years a main condition in mother was imputed when not reported in some cases. This practice has been ceased for the 2013 reference period leading to a reduction in the number of records assigned a code in the block P00-P04: Fetus and newborn affected by maternal factors and by complications of pregnancy, labour and delivery.
For further information on the 2014 review of the ABS causes of death collection and effects on the broader dataset, see: Technical Note 1, ABS Implementation of the Iris Software: Understanding Coding and Process Improvements.