CCS DRG Assignment & Case Mix

Question 1

What does 'case mix index' (CMI) measure in a hospital?

Accepted Answer

The average DRG relative weight for all inpatient discharges, reflecting patient complexity

Answer

The case mix index (CMI) is calculated by averaging the MS-DRG relative weights of all discharges in a period. A higher CMI indicates a more complex patient population and generates higher reimbursement.

Question 2

Which of the following secondary diagnoses would NOT qualify as a CC or MCC for MS-DRG assignment?

Accepted Answer

Essential hypertension (I10)

Answer

Essential hypertension (I10) is listed on the CC Exclusion List for many principal diagnoses and is generally not a CC or MCC - it is considered a common chronic condition without increased resource use impact.

Question 3

What is a 'present on admission' (POA) indicator, and why is it required on inpatient Medicare claims?

Accepted Answer

It identifies whether each diagnosis was present when the patient was admitted, distinguishing hospital-acquired conditions from pre-existing ones

Answer

POA indicators are required on Medicare inpatient claims to distinguish diagnoses present when the patient was admitted from hospital-acquired conditions (HACs), which may reduce reimbursement.

Question 4

A patient is admitted with pneumonia (MS-DRG 193, without CC/MCC) and is also found to have acute kidney injury. If the acute kidney injury qualifies as an MCC, the claim will be grouped to:

Accepted Answer

MS-DRG 191 - Pneumonia with MCC, higher relative weight

Answer

Acute kidney injury is an MCC. With an MCC present, simple pneumonia groups to MS-DRG 191 (Respiratory Infections and Inflammations with MCC), which has a higher relative weight than the without CC/MCC variant.

Question 5

What is the purpose of the Medicare Code Editor (MCE) in the DRG grouping process?

Accepted Answer

To identify invalid codes, age conflicts, sex conflicts, and manifestation code errors before DRG assignment

Answer

The Medicare Code Editor (MCE) is a software module that checks ICD-10-CM/PCS codes for validity and logical errors (age, sex conflicts, unacceptable principal diagnoses) before DRGs are assigned.

(CCS) Certified Coding Specialist Practice Test

(CCS) Certified Coding Specialist Practice Test

CCS DRG Assignment & Case Mix