Classifications

Summary of AR-DRG v4.1 to v4.2 changes

Links to files covering changes between ICD-10-AM first and second editions. These are: differences between logical and historical maps for ICD-10-AM 1st and 2nd editions; changes to DRG 961Z unacceptable principal diagnosis implemented in AR-DRG v4.2; diagnosis changes implemented in AR-DRG v4.2; procedure changes implemented in AR-DRG v4.2.

Incorporating changes between ICD-10-AM first and second editions

The National Centre for Classification in Health (NCCH) has released the ICD-10-AM second edition codes effective from 1 July 2000. Incorporating the changes to ICD-10-AM is the main purpose for the release of AR-DRG v4.2 in December 2000. The NCCH provided the Commonwealth with details of second edition codes, including maps of inserted and deleted codes. For full mapping tables see the National Centre for Classification in Health Web Site. Comments here will be restricted to the diagnosis and procedure codes, which are significant to the DRG classification.

Diagnoses

A total of 191 valid first edition disease codes were deleted for ICD-10-AM second edition and from the DRG classification through forward maps to valid second edition codes. There are 254 new valid ICD-10-AM second edition disease codes that have been inserted into AR-DRG v4.2 through their backward maps to valid first edition codes. In all 89 valid first edition disease codes are being reused as they were deleted and then inserted into ICD-10-AM second edition with changed meanings. These reused codes are in the Diabetes mellitus (E10-E14) grouping and the Paraplegia and tetraplegia (G82) three-character category.

Procedures

A total of 139 valid first edition procedure codes were deleted for ICD-10-AM second edition and from the DRG classification through forward maps to valid second edition codes. They consisted of 77 Operating Room procedures and 62 Non Operating Room procedures. There were nine DRG significant procedures included in these deletions which forward map to non-significant procedures. In addition there were 10 non-significant procedures deleted for ICD-10-AM second edition which forward map to DRG significant procedures.

There are 147 new valid ICD-10-AM second edition procedure codes that have been inserted into AR-DRG v4.2 through their backward maps to valid first edition codes. They consist of 110 Operating Room procedures and 37 Non Operating Room procedures.

Maps between ICD-10-AM first and second editions

The NCCH logical maps were used in converting AR-DRG v4.1 from ICD-10-AM first edition codes to ICD-10-AM second edition codes. These logical maps can be found here. The logical map is generally the same as the primary historical map except for a few cases where the historical map did not result in appropriate DRG placement. These cases are detailed at Attachment 1 at the end of this page.

Resolution of AR-DRG v4.1 issues

Since the release of AR-DRG v4.1 a number of difficulties with the classification have been brought to the notice of the Commonwealth. Some of these problems became obvious when State and Territories reviewed the maps between ICD-9-CM and ICD-10-AM. Hospitals notified the Commonwealth of other issues when individual patient records failed to group to the expected DRGs.

In order to rectify some of the more straightforward issues, the AR-DRG v4.1 classification was first forward mapped from ICD-10-AM first edition codes to second edition codes. Changes were then implemented in the mapped classification.

Diagnoses

The greatest number of disease code changes occur to DRG 961Z Unacceptable principal diagnosis. Following recommendations from the NCCH, 78 codes have been moved to this DRG and 47 have been moved out of DRG 961Z to other DRGs. See Attachment 2 at the end of this page for details of changes to DRG 961Z.

In addition to the DRG 961Z Unacceptable principal diagnosis changes, a total of 27 groups of disease code changes were made to the classification after the AR-DRG v4.1, with each change involving at least one code. For details of these changes refer to Attachment 3 at the end of this page where new second edition codes are italicised.

Procedures

There are 70 per cent more DRG significant ICD-10-AM procedures than there were in the ICD-9-CM procedure classification. Included in these extra ICD-10-AM codes are single procedure codes where two or more ICD-9-CM codes were needed and some changes were needed to improve the placement of these codes in DRGs. The maps for the deleted and inserted procedures highlighted some inconsistencies in the significance or otherwise of some procedures in the DRG classification. As a result some procedures are no longer significant in AR-DRG v4.2 and others have become significant. A total of 33 groups of procedure code changes made for AR-DRG v4.2. These changes are detailed at Attachment 4 at the end of this page where new second edition codes are italicised. 

Other changes

Changes to logic have been made for the following adjacent DRGs:

F07 Other Cardiothoracic/Vascular Procedures W Pump;
F15 Percutaneous Coronary Angioplasty W/O AMI W Stent Implantation;
F16 Percutaneous Coronary Angioplasty W/O AMI W/O Stent Implantation;
H03 Cholecystectomy W Closed CDE;
I01 Bilateral or Multiple Major Joint Procedures of Lower Extremity;
K01 Diabetic Foot;
Y01 Severe Full Thickness Burns; and
Y61 Severe Burns.

Three adjacent DRGs have had their descriptions changed to the following:

I60 Femoral Shaft Fractures;
I66 Inflammatory Musculoskeletal Disorders; and
I76 Other Musculoskeletal Disorders;

The descriptions of the DRGs within these adjacent DRGs have also been changed.

In addition to changes made to DRGs, the complication and comorbidity lists have been updated to reflect code and clinical changes. The clinical edits have also been updated to reflect ICD-10-AM second edition changes, and corrections were also made to the lists as advised by the NCCH.

Attachment 1. Differences between logical and historical maps for ICD-10-AM 1st and 2nd editions (PDF 8KB)

Attachment 2. Changes to DRG 961Z Unacceptable Principal Diagnosis implemented in AR-DRG v4.2 (PDF 13KB)

Attachment 3. Diagnosis changes implemented in AR-DRG v4.2 (PDF 11KB)

Attachment 4. Procedure changes implemented in AR-DRG v4.2 (PDF 16KB)

Note: If you are unable to view PDF files, printed copies of the above Attachments can be requested from the Department by email: casemix-hfs@health.gov.au