As of 1 July 2011 the Ministry of Health will be grouping all events to AR-DRG v6.0. AR-DRG v6.0 accepts ICD-10-AM 6th Edition codes so there is no mapping involved in the grouping process.
Variables used for grouping
Data items include:
- 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 v5.0 and AR-DRGs v6.0
Version 6.0 incorporates ICD-10-AM 6th Edition within the basic structure of Version 5.0.
The Adjacent DRG (ADRG) numbering sequence is the same as Version 5.0, which is no longer contiguous, and may not reflect the surgical and other hierarchies, in some Major Diagnostic Categories (MDC).
New features are summarised below.
- Neonates with a birth/admission weight between 100 to 399 grams will be grouped in Version 6.0 provided that they have been coded with any of the following diagnosis codes:
- P07.01 Extremely low birth weight 499g or less
- P07.21 Extreme immaturity, less than 24 completed weeks
- P07.22 Extreme immaturity, 24 or more completed weeks but less than 28.
- R45.81 Suicidal ideation moves from ADRG 961 Unacceptable Principal Diagnosis and groups to ADRG Z64 Other Factors Influencing Health Status.
- All cardiac valve procedures group together in ADRGs F03 Cardiac Valve Proc W CPB Pump W Invasive Cardiac Investigation and F04 Cardiac Valve Proc W CPB Pump W/O Invasive Cardiac Investigation.
- The pacemaker function has been revised and moves from DRG F17Z Cardiac Pacemaker Replacement to ADRG F12 Implantation or Replacement of Pacemaker, Total System.
- 39323-00  Other percutaneous neurotomy by radiofrequency and 39323-01  Other percutaneous neurotomy by cryoprobe have been removed from the classification. Cases regroup from ADRG I28 Other Connective Tissue Procedures to ADRG I68 Non-surgical Spinal Disorders.
- Fracture of clavicle (S42.0x; x=0-3, 9) moves from ADRG I75 Injury to Shoulder, Arm, Elbow, Knee, Leg or Ankle to ADRG I76 Other Musculoskeletal Disorders.
- ADRG J12 Lower Limb Procs W Ulcer/Cellulitis has been revised and cases regroup to ADRG J08 Other Skin Graft and/or Debridement Procedures.
- O70.2 Third degree perineal laceration during delivery loses its CC status.
- Z49.0 Preparatory care for dialysis moves from ADRG Z64 Other Factors Influencing Health Status to ADRG L67 Other Kidney and Urinary Tract Diagnoses. Surgical cases move from ADRG Z01 O.R. Procedures W Diagnoses of Other Contacts W Health Services to ADRG L09 Other Procedures for Kidney and Urinary Tract Disorders.
- A full review of ventilation throughout the classification results in deletion of A41 Intubation Age<16 and creation of B42 Nervous system Diagnosis W Ventilator Support, F43 Circulatory System Diagnosis W Non-Invasive Ventilation, T40 Infectious and Parasitic Disease W Ventilator Support and X40 Injuries, Poisoning and Toxic Effects of Drugs W Ventilator Support.
- New ADRGs: A10 Insertion of Ventricular Assist Devices, A11 Insertion of Implantable Spinal Infusion Device, A12 Insertion of Neurostimulator Device, E42 Bronchoscopy, E76 Respiratory Tuberculosis, J69 Skin Malignancy and L68 Peritoneal Dialysis.
- B40 Plasmapheresis W Neurological Disease has its definition changed to Plasmapheresis W Neurological Disease, Sameday.
- The definition of B60 Established Paraplegia/Quadriplegia W or W/O OR Procedures has been changed to Acute Paraplegia/Quadriplegia W or W/O OR Procedures and new B82 Chronic and Unspecified Paraplegia/Quadriplegia W or W/O OR Procedures has been created.
- The definition of D06 Sinus, Mastoid and Complex Middle Ear Procedures has been changed to Sinus and Complex Middle Ear Procedures and new D15 Mastoid Procedures has been created.
- D09 Miscellaneous Ear, Nose, Mouth and Throat Procedures has been deleted. Most D09 procedures moved to D12 Other Ear, Nose, Mouth and Throat Procedures.
- F70 Major Arrhythmia and Cardiac Arrest and F71 Non-Major Arrhythmia and Conduction Disorder have been combined to F76 Arrhythmia, Cardiac Arrest and Conduction Disorders.
- G10 Hernia Procedures Age<1 has its definition changed to Hernia Procedures and replaces G08 Abdominal and Other Hernia Procedures Age>0 and G09 Inguinal and Femoral Hernia Procedures Age>0.
- G42 Other Gastroscopy for Major Digestive Disease and G45 Other Gastroscopy for Non-Major Digestive Disease have been combined to G47 Other Gastroscopy.
- G43 Complex Colonoscopy and G44 Other Colonoscopy have been combined to G48 Colonoscopy.
- G67 Oesophagitis, Gastroenteritis and Misc Digestive System Disorders Age>9 has its definition changed to Oesophagitis and Gastroenteritis and replaces G68 Gastroenteritis Age<10 and G69 Oesophagitis and Misc Digestive System Disorders Age<10. The miscellaneous digestive system disorders moved to G70 Other Digestive System Diagnoses.
- H41 ERCP Complex Therapeutic Procedure and H42 ERCP Other Therapeutic Procedure have been combined to H43 ERCP Procedures.
- The definition of I03 Hip Revision or Replacement has been changed to Hip Replacement and new I31 Hip Revision has been created.
- The definition of I04 Knee Replacement and Reattachment has been changed to Knee Replacement and new I32 Knee Revision has been created.
- I14 Stump Revision has been deleted and the two procedures moved to I28 Other Musculoskeletal Procedures and I30 Hand Procedures.
- The definition of I65 Connective Tissue Malignancy, Including Pathological Fracture has been changed to Musculoskeletal Malignant Neoplasms and new I79 Pathological Fracture has been created.
- I69 Bone Diseases and Specific Arthropathies has its definition changed to Bone Diseases and Arthropathies and replaces I70 Non-specific Arthropathies.
- K40 Endoscopic or Investigative Procedure for Metabolic Disorders W/O CC has its definition changed to Endoscopic or Investigative Procedure for Metabolic Disorders.
- M40 Cystourethrosocpy W/O CC has its definition changed to Cystourethroscopy, Sameday.
- N02 Uterine, Adnexa Procedure for Ovarian or Adnexal Malignancy and N03 Uterine, Adnexa Procedure for Non-Ovarian or Adnexal Malignancy have been combined to N12 Uterine and Adnexa Procedures for Malignancy.
- Z40 Follow Up W Endoscopy has its definition changed Endoscopy W Diagnoses of Other Contacts W Health Services, Sameday.
- Z62 Follow Up W/O Endoscopy has been deleted. All Z62 diagnoses moved to Z64 Other Factors Influencing Health Status.
- Z63 Other Aftercare has its definition changed to Other Surgical Follow Up and Medical Care.
- Z65 Multiple, Other and Unspecified Congenital Anomalies has its definition changed to Congenital Anomalies and Problems Arising from Neonatal Period.
- 901 Extensive OR Procedure Unrelated to Principal Diagnosis, 902 Non-Extensive OR Procedure Unrelated to Principal Diagnosis and 903 Prostatic OR Procedure Unrelated to Principal Diagnosis have been combined to 801 OR Procedures Unrelated to Principal Diagnosis which is classified as unrelated OR ADRG, instead of error ADRG.
- A06 Tracheostomy and/or Ventilation >95 hours includes principal diagnosis for severity of illness calculation.
- A sex value of 3 Intersex or indeterminate bypasses the sex edit in MDCs 12 (male reproductive system), 13 (female reproductive system) and 14 (pregnancy, childbirth and puerperium) and will not cause episodes to group to 960 Ungroupable.
- Patients less than one year old and coded with diagnosis in code range P07.01 to P07.32 (low birth weight and immaturity) group to MDC 15 Newborns and other neonates.
- The hierarchy order of MDC assignments in Pre MDC, and ADRGs in surgical partitions and other partitions has been revised.
- All DRG splits have been revised. Age is not used for partitioning ADRGs, so no DRG has age as part of DRG definition.
(Department of Health and Ageing: AR-DRG v6.0 Definitions Manual, page 4.)
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.
- 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.
Events that contain clinically atypical or invalid information are assigned to one of three error DRGs in AR-DRG v6.0:
- 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 Definitions Manual Volume Three for more information.
Australian Refined Diagnosis Related Groups Version 6.0 Definitions Manual produced by the Australian Government Department of Health and Ageing.
The AR-DRG Definitions Manuals can be purchased from the National Casemix and Classification Centre (e-mail: firstname.lastname@example.org).