About classification

The classification systems used in New Zealand hospitals are the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM), the Australian Classification of Health Interventions (ACHI), Australian Coding Standards (ACS), collectively the classification is referred to as ICD-10-AM/ACHI/ACS and the Australian Refined Diagnosis Related Groups (AR-DRG).

ICD-10-AM is based upon the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) which is developed by the World Health Organization and modified by permission for Australian Government purposes (ICD-10-AM).

The following products are used in New Zealand to clinically code all inpatient and same day patients discharged from New Zealand public hospitals:

• ICD-10-AM – Alphabetic Index and Tabular List of Diseases and Health Related Problems
• ACHI – Alphabetic Index and Tabular List of Interventions Australian Coding Standards
• ACS – Australian Coding Standards
• Additional clinical coding advice and guidelines
• National reporting requirements and clinical coding conventions.

ICD-10-AM and ACHI Alphabetic Indices and Tabular Lists contain classification conventions and instructions.

The ACS are the national standards for coding of clinical data using ICD-10-AM and ACHI. The ACS provides classification guidelines that complement ICD-10-AM and ACHI.  The use of  ICD-10-AM and ACHI Alphabetic Indices and Tabular Lists, and ACS promotes consistency in the clinical coding of admitted episodes of care.

Additional clinical coding advice and guidelines are provided to facilitate consistent assignment and reporting of ICD-10-AM and ACHI codes where there are areas of ambiguity in the classification edition currently in use. National reporting requirements and clinical coding conventions are specific New Zealand rules and conventions for clinical coding practice and underpin consistency and accuracy of clinical coded information submitted to the national collection National Minimum Dataset (NMDS).

Each classification edition can contain significant changes to ICD-10-AM/ACHI codes and conventions, and coding standards. Therefore, it is important for data users when comparing trends over time and interpreting statistics to be aware that assumptions, code assignments and guidelines may change from one edition to another.

National Collections also manages the implementation of new ICD-10-AM/ACHI/ACS Editions and AR-DRG versions within New Zealand under the National Collections Annual maintenance Project (NCAMP).

If you require further information about the use and implementation of ICD-10-AM/ACHI/ACS in New Zealand contact us on coding_helpdesk@tewhatuora.govt.nz 

Classification development has been managed by several organisations since the first published ICD-10-AM/ACHI/ACS edition and AR-DRG version. 

The National Centre for Classification in Health (NCCH), University of Sydney, Australia was responsible for the development of the classification systems ICD-10-AM/MBS-E*/ACHI/ACS First Edition through to Seventh Edition and AN-DRG/AR-DRG v3.0 to v6.0x under contract to the Australian Department of Health and Ageing (DoHA).

*MBS-Extended was the name of the first Australian interventions classification until it was renamed to the Australian Classification of Health Interventions (ACHI) in Third Edition. 

The National Casemix and Classification Centre (NCCC), University of Wollongong, Australia was responsible for the development of the classification systems ICD-10-AM/ACHI/ACS Eighth Edition and AR-DRG v7.0 under the contract of the Independent Hospital and Pricing Authority (IHPA).

The Australian Consortium for Classification Development (ACCD) was responsible for the development of the classification systems ICD-10-AM/ACHI/ACS Ninth Edition through to Eleventh Edition and AR-DRG v8.0 to v10.0 under the contract of the Independent Hospital and Pricing Authority (IHPA).

The Independent Health and Aged Care Pricing Authority (IHACPA) formally known as Independent Hospital Pricing Authority (IHPA) was responsible for development of the classification systems ICD-10-AM/ACHI/ACS Twelfth Edition and AR-DRG v11.0. 

The development cycle of the classification systems ICD-10-AM/ACHI/ACS and AR-DRG occurred every two years. However, following a classification system review in 2020 Australia moved to a three year development cycle, which began with 10-AM/ACHI/ACS Twelfth Edition and AR-DRG v11.0. As part of the classification development New Zealand is invited to participate by nominating representatives from the National Collections team for two groups. These groups are:

1. The International Classification of Diseases (ICD) Technical Group (ITG) is an advisory group that provides expert classification advice and technical input on ICD-10-AM/ACHI/ACS development.
2. The Diagnosis Related Groups (DRG) Technical Group (DTG) is an advisory group that provides expert grouping advice and technical input on AR-DRG development.

If you require further information about ICD-10-AM/ACHI/ACS or AR-DRG development contact us on coding_helpdesk@tewhatuora.govt.nz