AR-DRG Version 8.0: Implementation of the Episode Clinical
Complexity Model
Carol Loggie
Introduction
Throughout the development of Version 8.0 the ACCD
worked in close consultation with the DRG Technical Group
The release of Australian Refined Diagnosis Related Groups
(DTG), the Classifications Clinical Advisory Group (CCAG)
(AR-DRG) Version 8.0 sees a major change in the methand the IHPA. Details regarding ACCD’s governance structure
odology used to measure case complexity. The new model
and consultation processes are available on the ACCD website
represents a significant shift away from the Patient Clinical
(https://www.accd.net.au/).
Complexity Level (PCCL) model using Complications and
Comorbidities (C&Cs), and allows for greater scope and
The development process
precision in splitting Adjacent DRGs (ADRGs) into DRGs.
The performance of the PCCL system was initially assessed
AR-DRG Version 8.0 will be used by the Independent
to determine the degree to which it needed to be modified,
Hospital Pricing Authority (IHPA) for the pricing of admitted
or possibly redeveloped. An evidence based review was
acute care from July 2016. Given the significant changes
completed which demonstrated that
from AR-DRG Version 7.0 with
The new model represents a significant the PCCL model performed poorly
the implementation of the Episode
in explaining episode cost variations
Clinical Complexity (ECC) Model it is
shift away from the Patient Clinical
within ADRGs. A literature review of
important that users of the AR-DRG
Complexity Level model ... and allows for international casemix classifications
Classification develop an underwas also undertaken which revealed
greater scope and precision
standing of the new model and the
a lack of consensus in the approach
implications of the changes.
to case complexity and also found
that there were no models in use internationally that could
Why review the case complexity model?
be adapted for use in Australia. Accordingly, the decision was
Case complexity, including the list of C&C diagnoses codes,
made to redevelop the case complexity model.
was implemented as part of the initial Australian casemix
It was planned that the development would consist of two
classification in the 1990s. The model was based on a DRG
phases, comprising the redevelopment of the model, followed
system from the United States, in which additional diagnoses
by the implementation of the new model into the AR-DRG
were considered to be ‘significant’ where they were associated
Classification with a review of ADRG splitting. Given the
with an increase in length of stay exceeding certain thresholds
scope of the project, a set of principles was established to
(Averill et al. 2003). There have been refinements made to the
guide the development work (detailed in the AR-DRG Version
C&C list and the case complexity algorithm over the years,
8.0 Definitions Manual).
however there has not been a review at a conceptual level
since implementation. A comprehensive assessment of the
The Episode Clinical Complexity Model
PCCL system was initiated due to:
The outcome of phase one was the ECC Model and as it
ƒƒ concerns about whether the model was still fit for
is markedly different from the approach taken in the PCCL
purpose due to a reliance on length of stay rather than
model, new terminology was developed in order to avoid
cost to determine case complexity
confusion. Table 1 provides a comparison of terminology used
ƒƒ the improvements in both the patient level data
between Version 7.0 and Version 8.0.
collections, including costing, and the computing capacity
for data analysis that had become available over the past
Diagnosis Complexity Level
two decades.
Of significance, the Complex Diagnoses (CDs) differ from
The review of the case complexity model was underC&Cs in that the majority of ICD-10-AM diagnoses codes
taken by the Australian Consortium for Classification
are in-scope to receive a nonzero case complexity weight, or
Development (ACCD) under the lead of the National Centre
Diagnosis Complexity Level (DCL). This has resulted in around
for Classification in Health (NCCH). This work was part of
12,500 ICD-10-AM codes that are now in-scope, in contrast
the ongoing development and maintenance of the AR-DRG
to the PCCL model where there was a defined list of codes
Classification System, which was contracted to the ACCD by
that could potentially be C&Cs. Codes for external cause,
the IHPA commencing in July 2013.
place of occurrence and activity are excluded from the DCLs.
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REPORT
Table 1: Case complexity terminology comparison between AR-DRG V7.0 and V8.0
AR-DRG V7.0
AR-DRG V8.0
Complication and/or Comorbidity
(CC) codes are the diagnoses that
may contribute to the calculation
of PCCL (i.e. affect the calculation
of episode level complexity).
Complex Diagnoses (CDs) in a
particular ADRG are the set (or
list) of diagnoses that may affect
the calculation of episode clinical
complexity in that ADRG. CDs
differ across ADRGs.
Complication and Comorbidity
Levels (CCLs) are values assigned
to diagnosis codes as complexity
weights, specific to the ADRG
of the episode. Only CC codes
receive nonzero CCLs.
Diagnosis Complexity Levels
(DCLs) are values assigned to
diagnosis codes as complexity
weights, specific to the ADRG of
the episode. The CDs of an ADRG
are those diagnoses assigned a
nonzero DCL.
Patient Clinical Complexity Level
(PCCL) is a value assigned to
episodes as the measure of the
cumulative effect of a patient’s
CCs.
Episode Clinical Complexity Score
(ECCS) is the measure of the
cumulative effect of DCLs for a
specific episode.
Mild, Moderate, Severe and
Catastrophic CCs are descriptive
terms used in the naming of DRGs
where PCCL has been used as a
splitting variable.
Minor, Intermediate, Major
and Extreme Complexity are
descriptive terms used in the
naming of DRGs where ECCS has
been used as a splitting variable.
Source: Adapted from the AR-DRG Version 8.0 Definitions Manual.
In addition there are:
ƒƒ Unconditional exclusions: codes that were considered to
be unsuitable for inclusion in the ECC Model, including
the majority of codes from Chapter 18 Symptoms, signs
and abnormal clinical and laboratory findings, not elsewhere
classified (R00-R99) and Chapter 21 Factors influencing
health status and contact with health services (Z00-Z99); the
unacceptable principal diagnosis (PDx) codes; other special
case exclusion codes; sequelae codes; and full-time dagger
codes.
ƒƒ Conditional exclusions: those codes in specific dagger and
asterisk pairs of DCL in-scope codes, where the dagger
code is a ‘part-time’ dagger. In these cases the asterisk
code prevents the dagger code from receiving a DCL.
Unconditional and conditional exclusions are always
assigned a DCL of zero. Full details of the excluded codes
can be found in the AR-DRG Version 8.0 Definitions Manual,
Appendix C.
DCLs are integer values that range from 0 to 5, a change
from CCLs that range from 0 to 4 for surgical and neonatal
episodes, and 0 to 3 for medical episodes.
Aggregation of codes for DCL
There is a process of aggregation when calculating the DCL
for each code to ensure the required sample size threshold
is obtained, with a total of seven hierarchical aggregation
levels. The finest level of precision for the diagnoses codes is
generally to the three character level, that is, codes with four
and five characters are aggregated to the three character level.
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There is one exception to this default, which is the N18.range of codes for chronic kidney disease, which are enhanced
to the fourth character level in order to capture the variation
in complexity within this code range. Other aggregation levels
include block level and chapter level.
Episode Clinical Complexity Score
The Episode Clinical Complexity Score (ECCS) uses
the DCLs in an episode to estimate the overall cost of the
episode. The ECCS is calculated by ranking an episode’s DCLs
in descending order and then applying a decay component
(0.84) to successive diagnoses so that multiple DCLs make
diminishing contributions to the ECCS in order to account for
the ‘overlapping’ of costs. This means for example, that where
an episode has two diagnoses each with a DCL of 1, the
combined value will be less than 2.
An important change to be noted in the ECC Model is
that the principal diagnosis (PDx) code is also considered in
the case complexity for each episode, meaning that it is now
also in-scope to receive a nonzero DCL. This change was
as a result of investigative work that demonstrated that all
diagnoses, including the PDx, are important in the calculation
of complexity. The inclusion of the PDx ensures that all the
clinical concepts in an episode are recognised.
ECCS values range between 0 and 32, in comparison with
the PCCLs which range from 0 to 4. However, during the
development the large majority of episodes were demonstrated to have an ECCS of 5 or less, with only 0.5% having an
ECCS above 10.
DCL/ECCS calculator
Given the large number of in-scope codes in the ECC Model,
it was not practicable to provide a table of the codes in the
AR-DRG Definitions Manual as was previously done for the
C&C codes. Therefore, a DCL/ECCS Calculator has been
provided on the ACCD website as a web application. The
calculator can be used to assist in finding DCLs and computing
the ECCS for an individual episode within a particular ADRG.
However, it is important to note that the calculator is not
a grouper, and so the process of assigning an episode to an
ADRG or indicating the episode’s DRG is not part of its
functionality.
Implementation of the Model and review
of the ADRG splits
Following the completion of the ECC Model, phase two of
the Version 8.0 development was the review of all ADRG
splits using the new model.Various splitting options were
considered for each ADRG, with a preference for ADRG
splits to be based only on the ECCS in order to minimise the
use of non-complexity splitting variables. In consultation with
the DTG and CCAG, use of ECCS only was selected as the
optimal splitting variable in 315 ADRGs, with a reduction to
six ADRGs using other splitting variables, as seen in Table 2.
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The ECC Model was demonstrated to provide a
major improvement in the measurement of case
complexity ... and will facilitate more streamlined
updating over time
Table 2: ADRG splitting comparison between AR-DRG V7.0 and V8.0
Number (%) of ADRGs
ADRG splitting
V7.0
V8.0
Nil – no split
127 (32%)
82 (20%)
ADRG split by
PCCL/ECCS only
168 (42%)
315 (78%)
ADRG split by PCCL/ECCS with
other(s)
74 (18%)
5 (1%)
ADRG split by Other(s) only
34 (8%)
1 (0%)
403
403
Total
Note:
3 error ADRGs not included.
As a result of the splitting review, the total number of
DRGs has increased from 771 in Version 7.0 to 807 in Version
8.0, primarily due to the creation of a split based on ECCS
where there was no split previously. Also, the types of noncomplexity variables used have decreased from seven variables
in Version 7.0 to two variables in Version 8.0, as below in
Table 3.
Table 3: Non-complexity ADRG splitting criteria used in V8.0
Splitting variable(s)
ADRG
Age (and ECCS)
A07 Allogeneic Bone Marrow Transplant
A09 Kidney Transplant
Transfer (and ECCS)
B70 Stroke and Other Cerebrovascular
Disorders
B78 Intracranial Injuries
F62 Heart Failure and Shock
Transfer (only)
F60 Circulatory Disorders, Admitted for AMI
W/O Invasive Cardiac Investigative Procs
Another change of note is that the ECC Model has
replaced the major problem, other problem and complicating
procedure lists in MDC 15 Newborns and other Neonates.
Classification structure
While there is an increase in the total number of DRGs
following the implementation of the ECC Model, the structure
of the AR-DRG classification is largely the same as in Version
7.0, retaining 406 ADRGs comprising 403 non-error ADRGs
and three error ADRGs. The logic used in the classification has
been simplified, with less reliance on non-complexity variables
such as length of stay, to assign episodes into DRGs.
The ECC Model was demonstrated to provide a major
improvement in the measurement of case complexity in
comparison to the PCCL system, and will facilitate more
streamlined updating of the classification over time to utilise
ongoing improvements in the available data and incorporate
changes in clinical practice.
Educational resources
An educational tutorial on AR-DRG Version 8.0 has been
provided on the ACCD website, along with a short quiz as
an additional tool to help reinforce the understanding of the
ECC Model and the changes in the new version. The education
package is intended for users with a basic understanding of
the AR-DRG Classification. Additional resources can be found
on both the ACCD and IHPA websites, including detailed
reports by ACCD on the two major phases of the Version 8.0
development.
The AR-DRG Version 8.0 Definitions Manual is available
for purchase through IHPA and incorporates detailed information on the changes to the classification.
Reference
Averill, R.F., Goldfield, N., Hughes, J.S., Bonazelli, J., McCullough, E.C.,
Steinbeck, B.A., Mullin, R., Tang, A.M., Muldoon, J., Turner, L. and Gay,
M.D. (2003). 3M All Patient Refined Diagnosis Related Groups (APR-DRGs)
Version 20.0 methodology overview. Available at https://www.hcup-us.
ahrq.gov/db/nation/nis/APR-DRGsV20MethodologyOverviewandBibli
ography.pdf (accessed 4 Nov 2015).
Other changes in AR-DRG Version 8.0
Some modifications were made to the classification as a result
of public submissions, which are detailed in the AR-DRG
Version 8.0 Definitions Manual. In addition, a review of the
ADRG hierarchical order within the ‘surgical’ and ‘other’ partitions resulted in one change in MDC 08 Diseases and Disorders
of the Musculoskeletal System and Connective Tissue, moving
I27 Soft Tissue Procedures ahead of I30 Hand Procedures in the
surgical hierarchy.
Carol Loggie, AssocDip(MRA), GCertHlthServ(R&D)
Coordinator, AR-DRG Development
Australian Consortium for Classification Development
National Centre for Classification in Health
Faculty of Health Sciences, University of Sydney
75 East Street, Lidcombe NSW 2141
email: [email protected]
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