1. APR DRG Classification Data Elements
MDC (Major Diagnostic Category)
Base APR DRG
(316 base APR DRG categories)
Four Severity of Illness Subclasses*
Subclass Severity
1 Minor
2 Moderate
3 Major
4 Extreme
Four Risk of Mortality Subclasses
* Severity subclasses have APR DRG weights for each subclass.
APR DRGs are first classified into major diagnostic categories, followed by base APR DRGs
These are the components of APR DRG adjusted data for both Severity of Illness (how sick one is) and Risk of Mortality (how likely one is to die).
Major Diagnostic Category
APR DRG
SOI Subclass
ROM Subclass

2. Underlying Principle of 3M™ APR DRGs
Severity of illness (SOI) and risk of mortality (ROM) are dependent on the patient’s underlying problem.
High severity of illness and risk of mortality are characterized by multiple serious diseases and the interaction among those diseases.
A few slides to explain the very basics of All Patient Refined DRGs. First and foremost, the underlying principle of APR DRGs is that the severity of illness and risk of mortality of a patient are dependent on the underlying problems that the patient brings with them.
A high severity of illness and a high risk of mortality are characterized by multiple serious underlying diseases, and how those diseases interact with each other.
For example – Severity of Illness: A Knee replacement patient due to sports injuries with no chronic diseases versus a knee replacement patient over 65 with heart disease, hypertension, and diabetes.
For example – Risk of Mortality: An infection patient who is also immune-suppressed and due to other diseases is more severely ill, is at a much higher risk of dying than a patient admitted with an infection and a broken arm
Should these patients be compared to each other as equals when evaluating length of stay or mortality?

3. 3M™ APR DRG Assignment is Driven by:
Principal diagnosis
Procedures performed
All secondary diagnoses
Age
Gender

4. Example of Progression of Severity of Illness Subclass
Secondary Diagnosis of
Diabetes Mellitus 1
Minor
Uncomplicated Diabetes (250.0x) 2
Moderate
Diabetes with Renal Manifestation (250.4x) 3
Major
Diabetes with Ketoacidosis (250.1x) 4
Severe
Diabetes with Hyperosmolar Coma (250.2x)
The calculation of SOI and ROM involves 18 steps over 3 phases. The initial step is to assign the standard or default SOI level to each individual secondary diagnosis. The next 17 steps apply logic to calculate the overall patient SOI. For example, secondary diagnosis are compared to each other and the principal diagnosis for duplication. APR DRG assignment and the patient’s age are evaluated, and other other criteria are applied.
Here is an example of the standard or default SOI assignment for some diabetes codes.

5. Example of Progression of Risk of Mortality Subclass
Secondary Diagnosis of
Cardiac Arrhythmias 1
Minor
Premature beats (427.60) 2
Moderate
Sinoatrial Node Dysfunction (427.81) 3
Major
Paroxysmal Ventricular Tachycardia (427.1) 4
Severe
Ventricular Fibrillation (427.41)
And here is an example of the standard ROM level for cardiac codes.
For example, premature beats are not necessarily life threatening while ventricular fibrillation could certainly result in death.
ROM is calculated separately and distinctly from SOI codes.

6. SOI and ROM are Independent
The severity of illness and risk of mortality subclass are calculated separately and may be different from each other.
Severity of Illness is a weight base
ROM is based on many factors including age & gender
ROM = 1
Low risk of mortality
Major severity of illness
SOI = 3
Acute Cholecystitis
Example: Acute Cholecystitis (Gall bladder attack)
Patient is severely ill, organ is in extreme state of decomposition
However, we have a very effective intervention that does not pose a high risk of death to the patient.