What Is DRG (Diagnosis-Related Group)?
A DRG is the inpatient hospital classification system that groups admissions with similar clinical characteristics and resource use into a single payment category; CMS uses MS-DRGs to pay hospitals under the IPPS for Medicare inpatient stays.
- Inpatient hospital coding accuracy directly drives DRG assignment and IPPS payment.
- CDI (Clinical Documentation Improvement) programs target documenting and capturing all MCCs/CCs to ensure DRG assignment reflects true case severity, which impacts both payment and quality reporting.
DRG (Diagnosis-Related Group)
Also known as: MS-DRG; Medicare Severity Diagnosis-Related Group; Diagnosis Related Group
A DRG is the inpatient hospital classification system that groups admissions with similar clinical characteristics and resource use into a single payment category; CMS uses MS-DRGs to pay hospitals under the IPPS for Medicare inpatient stays.
Definition
Originally developed at Yale in the 1970s, the DRG system groups inpatient hospital cases by principal diagnosis, secondary diagnoses, procedures performed (ICD-10-PCS), age, sex, and discharge status. CMS introduced the MS-DRG (Medicare Severity DRG) version in 2007 to better reflect severity by splitting many DRGs into three tiers based on Major Complications/Comorbidities (MCC), Complications/Comorbidities (CC), or neither. There are roughly 760 MS-DRGs as of FY 2024. Each DRG has a relative weight; the hospital's IPPS payment is the DRG weight times the hospital's base rate, with adjustments for wage index, IME, DSH, and outliers. MS-DRGs are updated annually in the IPPS Final Rule.
Example
MS-DRG 469 (Major joint replacement or reattachment of lower extremity with MCC) carries a higher relative weight than MS-DRG 470 (without MCC). Documenting an MCC such as acute renal failure (N17.9) or sepsis (A41.9) shifts a total knee replacement case from MS-DRG 470 to 469, materially affecting the hospital's payment.
Common Misconceptions
DRGs are not used for outpatient services or physician fees — those use APCs (hospital outpatient) and CPT/RVUs (physician). DRGs do not reflect the actual cost of an admission; they are a fixed prospective payment that creates incentive to manage length of stay and resource use.
Practical Application
Inpatient hospital coding accuracy directly drives DRG assignment and IPPS payment. CDI (Clinical Documentation Improvement) programs target documenting and capturing all MCCs/CCs to ensure DRG assignment reflects true case severity, which impacts both payment and quality reporting.
Related Terms
ICD-10-CM
ICD-10-CM is the U.S. clinical modification of the WHO's ICD-10 diagnosis code set, maintained by the CDC's National Center for Health Statistics, used to report diagnoses on all HIPAA-covered claims.
Read definition arrow_forwardICD-10-PCS
ICD-10-PCS is the U.S. inpatient hospital procedural code set maintained by CMS, with seven-character alphanumeric codes used exclusively to report procedures performed during inpatient hospital admissions for billing under MS-DRGs.
Read definition arrow_forwardUB-04 form
The UB-04 (also known as CMS-1450) is the standard paper claim form used by institutional providers (hospitals, SNFs, home health, hospice) to bill Medicare and other payers; its electronic equivalent is the 837I (Institutional) HIPAA EDI transaction.
Read definition arrow_forwardAPC (Ambulatory Payment Classification)
An APC is the hospital outpatient classification system used by CMS under the Outpatient Prospective Payment System (OPPS) to group similar outpatient services for prospective payment to hospitals.
Read definition arrow_forwardWhere This Applies on MedPrecision
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