Cause Of Death Coding

What changes are taking place in Irish mortality statistics?

Underlying Cause of Death will be classified according to International Classification of Diseases, Version 10 (ICD10) instead of to International Classification of Diseases, Version 9 (ICD9).
Simultaneously with the move from ICD9 to ICD10, we are changing from choosing Underlying Cause of Death manually in all cases to using the automated coding system developed by the U.S National Centre for Health Statistics (NCHS).

What is the timetable for these changes?

All deaths registered on or after 1st January 2007 are being coded to ICD10. The Vital Statistics publication for Quarter 1 2007 (to be published in September 2007) will be the first in which cause of death statistics are specified using ICD10 codes.

Why are these changes taking place?

Most European countries, and many countries worldwide, code deaths using ICD10. Changing to ICD10 will make our cause of death statistics more easily comparable with these countries. Similarly, using an automated coding system will make our statistics more comparable.

What effect will these changes have on Cause of Death statistics?

The number of deaths assigned to many Cause of Death categories should not be greatly altered by these changes. However, many countries have found that moving to ICD10 does affect certain specific categories. In particular, a significant drop in the number of deaths attributed to pneumonia and bronchopneumonia has been observed in some countries after moving to ICD10. These deaths were instead assigned to other conditions included on the death certificate.

What guidelines are being produced to help interpret these changes?

We are currently completing a Bridge Coding study based on deaths registered in 2005. In this study, deaths that were previously coded in ICD9 using manual coding are being recoded independently in ICD10 using the automated system. The resulting differences in the number of deaths assigned to specific causes using the respective methods will give us a good insight into the effect of these changes on future mortality statistics. We are aiming to publish the results of this study in August 2007.

How does ICD10 differ from ICD9?

ICD10 uses alphanumeric codes instead of the numeric codes used in ICD9. For example, ‘malignant neoplasm of stomach’ has changed from 151 in ICD9 to C16 in ICD10. As previously, a fourth digit may be used for sub-categories.
ICD10 has a total of approximately 8,000 unique codes, over 3,000 more than ICD9.
Some of the rules by which Underlying Cause of Death is chosen have been changed.

How can I find out more about these changes?

If you have any queries, or you want to find out more about these changes, contact the CSO at information@cso.ie