Australian Refined Diagnosis Related Groups v6.0x (AR-DRG v6.0x)

The Ministry of Health has been grouping all events with an event end date on or after 1 July 2013 to AR-DRG v6.0x. AR-DRG v6.0x accepts ICD-10-AM/ACHI 6th Edition codes. ICD-10-AM/ACHI 8th Edition was implemented 1 July 2014. Events coded in 8th Edition will have their codes back-mapped to ICD-10-AM/ACHI 6th Edition, and from there will be grouped into AR-DRG v6.0x. The cost weights and WIESNZ methodology will then be applied.

DRG Grouper Type

DRG grouper type code DRG grouper type description MDC type
01 Medicare Version 4.0 Secondary Care  
02 ANDRG Version 3.1 A
03 AR-DRG Version 4.1 B
04 AR-DRG Version 4.2 C
05 AR-DRG Version 5.0 D
06 AR-DRG Version 6.0 E
07 AR-DRG Version 6.0x F

 Cost Weight Code

01 = WIES5a
02 = WIES5a
03 = WIES8a
04 = WIES8B
05 = WIES8c
06 = WIES11a
07 = WIES11b
08 = WIES11c
09 = WIESNZ08
10 = WIESNZ09
11 = WIESNZ10
12 = WIESNZ11
13 = WIESNZ12
14 = WIESNZ13
15 = WIESNZ14
16 = WIESNZ15

Variables used for grouping

Data items include:

  • Diagnosis
  • Procedures
  • Sex
  • Age
  • Event end type
  • Length of stay
  • Leave days
  • Admission weight
  • Mental health legal status
  • Same-day status.

The AR-DRG can take up to 30 diagnosis codes and 30 procedure codes per event.

The grouper performs the following tasks in the order given:

  • Demographic and clinical edits
  • MDC assignment
  • Pre-MDC processing
  • MDC processing
  • Adjacent DRG assignment
  • CCL and PCCL assignment
  • DRG assignment.

Differences between AR-DRGs v6.0 and AR-DRGs v6.0x

Version 6.0x incorporates ICD-10-AM 6th Edition within the basic structure of Version 6.0.

The Adjacent DRG (ADRG) numbering sequence is the same as Version 6.0.

Listed below are the differences between AR-DRG v6.0 and AR-DRG v6.0x.

AR-DRG v6.0x reinstated 10 DRGs from AR-DRG v5.0.  These additional 10 DRGs are from breast malignancies, maternity and mental health, see below.

MDC 09 Diseases and disorders of skin, subcutaneous tissue and breast

  • Splits for malignant versus non-malignant disease for J06 Major Procedures for Breast Conditions and J07 Minor Procedures for Breast Conditions

MDC 14 Pregnancy, childbirth and the puerperium

  • An additional patient clinical complexity level (PCCL) split for O01 Caesarean Delivery
  • PCCL and diagnosis splits for O60 Vaginal Delivery
  • Splits for gestation and PCCL for O64 False Labour
  • A same day split for O66 Antenatal and Other Obstetric Admission

MDC 19 Mental diseases and disorders

  • A split for mental health legal status for U61 Schizophrenia Disorders
  • A combination age and PCCL split for U63 Major Affective Disorders

MDC 20 Alcohol/drug use and alcohol/drug induced organic mental disorders

  • A PCCL split for V60 Alcohol Intoxication and Withdrawal

(Independent Hospital Pricing Authority: AR-DRG v6.0x Definitions Manual Addendum, page 6.)

The AR-DRG v6.0x Definitions Manual Addendum is available for download from the Independent Health and Aged Care Pricing Authority website.

AR-DRG numbering system

The format of each AR-DRG number consists of four alphanumeric characters organised in terms of ‘ADDS’, where:

A indicates the broad group to which the DRG belongs (MDC)

DD identifies the adjacent DRG (ADRG) within the MDC, and the partition to which the ADRG belongs. An ADRG consists of one or more DRGs generally defined by the same diagnosis or procedure code list but have differing levels of resource consumption and are partitioned on the basis of several factors, including diagnoses/procedures used as a severity split, sameday, and level of comorbid disease and/or clinical complication.

The second and third characters (DD) identify the ADRG grouping and partition to which the ADRG belongs. These ranges are:

  • 01 to 39 = surgical
  • 40 to 59 = other
  • 60 to 99 = medical.

For example:

  • P67D Neonate, AdmWt >2499 g W/O Significant OR Procedure W/O Problem belongs to a medical partition
  • I09B Spinal Fusion W/O Catastrophic CC belongs to a surgical partition
  • E41Z Respiratory System Diagnosis W Non-Invasive Ventilation belongs to the other partition.

S is a split indicator that ranks DRGs within ADRGs on the basis of their consumption of resources, for example:

A = highest consumption of resources
B = second highest consumption of resources
C = third highest consumption of resources
D = fourth highest consumption of resources
Z = no split for the adjacent DRG.

Unrelated OR DRGs

Patients whose OR procedures are unrelated to the patient’s principal diagnosis are assigned to one of the three unrelated OR DRGs.

801A OR Procedures Unrelated to Principal Diagnosis W Catastrophic CC
801B OR Procedures Unrelated to Principal Diagnosis W Severe or Moderate CC
801C OR Procedures Unrelated to Principal Diagnosis W/O CC

Typically, these are patients admitted for a medical condition who develop a complication unrelated to the principal diagnosis and later have an OR procedure performed for the complication or a condition associated with the complication.

Error DRGs

Events that contain clinically atypical or invalid information are assigned to one of three error DRGs in AR-DRG v6.0x:

960Z Ungroupable
961Z Unacceptable Principal Diagnosis
963Z Neonatal Diagnosis Not Consistent w Age/Weight.

These error DRGs fall into two groups.

Group 1: 961Z and 963Z are used when the principal diagnosis will not allow the episode to be assigned to a clinically coherent DRG. For example, an ICD-10-AM code may be given as a principal diagnosis, when Australian Coding Standards state that the code is unacceptable as a principal diagnosis.

Group 2: 960Z is used when the principal diagnosis is invalid, or when other essential information is missing or incorrect.

In general, Group 1 relates more to coding standards, while Group 2 relates to coding quality.

Complication and Comorbidity Levels (CCLs) and Patient Clinical Complexity Levels (PCCLs)

CCLs are severity weights given to diagnoses. They range in value from 0 to 4 for surgical and neonate episodes, and from 0 to 3 for medical episodes, and have been developed through a combination of medical judgement and statistical analysis.

PCCLs are a measure of the cumulative effect of a patient’s complications and comorbidities, and are calculated for each episode.

This information is only an introduction. Obviously, CCLs and PCCLs are very complex concepts. Please refer to the Appendix C of the AR-DRG v6.0 Definitions Manual Volume Three for more information.

AR-DRG v6.0 Definitions Manuals can be purchased from the Independent Health and Aged Care Pricing Authority.


Australian Refined Diagnosis Related Groups Version 6.0 Definitions Manual produced by the Australian Government Department of Health and Ageing

Australian Refined Diagnosis Related Groups Version 6.0x Addendum produced by the National Casemix and Classification Centre (NCCC), Australia Health Services Research Institute, Univeristy of Wollongong

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