MS-DRG
An MS-DRG (Medicare Severity-Diagnosis Related Group) classifies an inpatient hospital stay into a payment group based on diagnoses and procedures, driving a single bundled payment.
Updated
An MS-DRG — Medicare Severity-Diagnosis Related Group — is a classification system that groups inpatient hospital cases into payment categories based on the principal diagnosis, complicating conditions, and procedures performed. Each MS-DRG carries a relative weight that, combined with the hospital's rate, produces a single bundled payment for the stay rather than a line-item payment per service.
MS-DRGs are used by Medicare's Inpatient Prospective Payment System and adopted by other payers in varying forms. The assignment reflects severity — cases with complicating conditions generally map to higher-weighted MS-DRGs — so accurate documentation and coding directly affect which group, and therefore which payment, the stay receives.
In practice
Because the MS-DRG is derived from coded diagnoses and procedures, a coding change or a missed complication can shift the case to a different group and a different payment. Hospitals monitor case-mix index (the average MS-DRG weight) as a measure of documented severity, and audits commonly test whether the documentation supports the MS-DRG assigned.
Commonly confused with
- Ambulatory Payment Classification: An APC groups outpatient hospital services into payment categories; an MS-DRG groups inpatient hospital stays. Both are prospective payment groupers but apply to different settings.