CDIP APR-DRG System, Severity of Illness (SOI), and Risk of Mortality (ROM) — Questions and Answers
Question 1: In the APR-DRG grouping system, 'Severity of Illness' (SOI) is best defined as:
- The probability that a patient will die during the hospitalization
- The total number of secondary diagnoses present at discharge
- The extent of physiologic decompensation or organ system loss of function (Correct answer)
- The financial weight assigned to the base APR-DRG
Correct answer: The extent of physiologic decompensation or organ system loss of function
In the APR-DRG system (developed by 3M), Severity of Illness measures the degree of physiologic decompensation or loss of organ system function caused by the patient's illnesses. It is distinct from Risk of Mortality, which estimates the likelihood of in-hospital death.
Question 2: APR-DRG Severity of Illness and Risk of Mortality subclasses are each rated on which scale?
- 0 to 3 (0=none through 3=major)
- 1 to 4 (1=minor, 2=moderate, 3=major, 4=extreme) (Correct answer)
- 1 to 5 (1=minimal through 5=extreme)
- A to D (A=minor through D=extreme)
Correct answer: 1 to 4 (1=minor, 2=moderate, 3=major, 4=extreme)
Both SOI and ROM in the APR-DRG system are scored on a 1–4 scale: 1=Minor, 2=Moderate, 3=Major, 4=Extreme. These subclass designations affect reimbursement for APR-DRG payers and are used for quality outcomes reporting.
Question 3: Which payer type most commonly uses APR-DRGs as a basis for hospital inpatient reimbursement?
- Medicare fee-for-service (Traditional Medicare)
- TRICARE/military health plans
- Medicaid programs and many commercial managed care health plans (Correct answer)
- Indian Health Service (IHS) facilities
Correct answer: Medicaid programs and many commercial managed care health plans
APR-DRGs were developed by 3M Health Information Systems and are widely used by state Medicaid programs and commercial managed care payers for hospital inpatient reimbursement. Medicare fee-for-service uses the MS-DRG system, not APR-DRGs.
Question 4: A patient admitted with sepsis develops acute kidney injury during the stay, which the hospitalist documents but does not explicitly link to the sepsis. Clarifying this causal relationship through a physician query would most likely result in:
- No impact on APR-DRG assignment since sepsis already carries high severity
- A reduction in the SOI subclass by adding a competing diagnosis
- An impact only on outpatient reimbursement, not inpatient APR-DRG grouping
- An increase in both SOI and ROM subclasses, more accurately reflecting the patient's clinical complexity (Correct answer)
Correct answer: An increase in both SOI and ROM subclasses, more accurately reflecting the patient's clinical complexity
Documenting acute organ dysfunction (such as acute kidney injury) as a complication of sepsis elevates the clinical picture significantly. In APR-DRG logic, organ dysfunction attributable to the principal diagnosis raises both the SOI and ROM subclass assignments, more accurately capturing the patient's severity and improving quality reporting accuracy.
Question 5: A post-discharge query would affect a patient's APR-DRG SOI and ROM subclasses but would NOT change the MS-DRG assignment. This query is still clinically valuable primarily because:
- It can retroactively increase Medicare reimbursement after the claim is paid
- It improves accuracy of quality reporting, outcomes benchmarking, and Medicaid or commercial payer reimbursement (Correct answer)
- CMS regulations require all post-discharge queries within 60 days of discharge
- It eliminates the requirement for present-on-admission (POA) indicator review
Correct answer: It improves accuracy of quality reporting, outcomes benchmarking, and Medicaid or commercial payer reimbursement
Post-discharge queries that affect SOI and ROM are valuable even without MS-DRG impact because they improve the accuracy of hospital quality scorecards (e.g., observed-to-expected mortality ratios), APR-DRG-based Medicaid and commercial reimbursement, and public reporting data. Accuracy in these metrics has real operational and reputational consequences.
Question 6: In the APR-DRG system, 'Risk of Mortality' (ROM) data is most commonly applied for which purpose?
- Assigning MS-DRG relative weights for Medicare inpatient claims
- Determining CC/MCC status for secondary ICD-10-CM diagnosis codes
- Setting a patient's expected length of stay for utilization management decisions
- Comparing a hospital's observed-to-expected in-hospital mortality ratio for quality benchmarking (Correct answer)
Correct answer: Comparing a hospital's observed-to-expected in-hospital mortality ratio for quality benchmarking
ROM subclass data feeds into quality benchmarking tools that compare a hospital's actual (observed) in-hospital mortality against what would be expected given the severity of its patient population. This O/E ratio is used in public reporting, accreditation, and value-based purchasing programs. ROM does not affect MS-DRG or CC/MCC determination.
CDIP APR-DRG System, Severity of Illness (SOI), and Risk of Mortality (ROM)
In the APR-DRG grouping system, 'Severity of Illness' (SOI) is best defined as: