Key facts for DRG 478
- FY2027 relative weight
- 2.4340
- Higher than 72% of all MS-DRGs
- Change vs FY2026
- -1.0%
- FY2026 weight 2.4590
- Geometric mean LOS
- 5.3 days
- Arithmetic mean 6.5 days
- MDC
- 08
- Diseases and Disorders of the Musculoskeletal System and Connective Tissue
- Severity level
- with CC (complication or comorbidity)
- Transfer policy
- Post-acute transfer DRG
- Special-pay DRG
TL;DR
MS-DRG 478 is a surgical group in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue) at the middle severity level of its family. CMS assigns it a FY2027 relative weight of 2.4340 with a geometric mean length of stay of 5.3 days and an arithmetic mean of 6.5. Its weight moved down 1.0% from FY2026 (2.4590). That weight is higher than 72% of all surgical and medical MS-DRGs. Its CC/MCC family (DRG 477, DRG 479) spans weights 1.8530 to 3.4030. The v44 Definitions Manual assigns it through 431 operating room procedures codes.
What changed from FY2026 to FY2027
CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 478 the FY2027 relative weight is 2.4340 against 2.4590 in FY2026, a fall of 1.02%.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 2.4590 | 2.4340 | -0.0250 |
| Geometric mean LOS (days) | 5.4 | 5.3 | -0.1 |
| Arithmetic mean LOS (days) | 6.7 | 6.5 | -0.2 |
CC and MCC family
DRG 478 shares its base definition with 2 other MS-DRGs split by severity. The family's weights span 1.8530 to 3.4030, a 1.84× spread, which is the payment effect of documenting qualifying complications and comorbidities.
| DRG | Title | FY2027 weight | GMLOS |
|---|---|---|---|
| 477 | Biopsies of Musculoskeletal System and Connective Tissue with MCC or Insertion of Antibiotic-eluting Bone Void Filler | 3.4030 | 8.1 |
| 478 | Biopsies of Musculoskeletal System and Connective Tissue with CC | 2.4340 | 5.3 |
| 479 | Biopsies of Musculoskeletal System and Connective Tissue without CC/MCC | 1.8530 | 3.3 |
Grouper logic (v44 Definitions Manual)
Operating Room Procedures: 431 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| 0MJX0ZZ | Inspection of Upper Bursa and Ligament, Open Approach |
| 0MJX4ZZ | Inspection of Upper Bursa and Ligament, Percutaneous Endoscopic Approach |
| 0MJY0ZZ | Inspection of Lower Bursa and Ligament, Open Approach |
| 0MJY4ZZ | Inspection of Lower Bursa and Ligament, Percutaneous Endoscopic Approach |
| 0N900ZX | Drainage of Skull, Open Approach, Diagnostic |
| 0N903ZX | Drainage of Skull, Percutaneous Approach, Diagnostic |
| 0N904ZX | Drainage of Skull, Percutaneous Endoscopic Approach, Diagnostic |
| 0N910ZX | Drainage of Frontal Bone, Open Approach, Diagnostic |
| 0N913ZX | Drainage of Frontal Bone, Percutaneous Approach, Diagnostic |
| 0N914ZX | Drainage of Frontal Bone, Percutaneous Endoscopic Approach, Diagnostic |
| 0N930ZX | Drainage of Right Parietal Bone, Open Approach, Diagnostic |
| 0N933ZX | Drainage of Right Parietal Bone, Percutaneous Approach, Diagnostic |
Documentation and denial exposure
As a surgical DRG, assignment depends on a qualifying operating-room procedure being coded from the operative report; a missing or non-OR procedure code drops the stay into a medical DRG in MDC 08 with a lower weight. Because this family splits by severity, auditors target CC and MCC capture: each secondary diagnosis must be documented as present, monitored, evaluated or treated during the stay to survive a DRG-validation review. Typical inpatient denial codes for this group: CARC 16 (claim lacks information needed to group the stay), CARC 50 (the admission or procedure is judged not medically necessary), CARC 97 (a service is bundled into the DRG payment).
How QuickIntell uses DRG 478 data
QuickCode groups inpatient encounters against the current v44 logic, flags CC and MCC candidates that lack supporting documentation, and shows the weight difference across the family before the claim drops. QuickScribe captures the attending's language that supports severity, and QuickRCM works DRG-validation denials with the grouper evidence attached.
Frequently asked questions — DRG 478
What is MS-DRG 478?
MS-DRG 478 is "Biopsies of Musculoskeletal System and Connective Tissue with CC", a surgical Medicare Severity Diagnosis-Related Group in MDC 08, Diseases and Disorders of the Musculoskeletal System and Connective Tissue. Medicare pays inpatient stays grouped here at the hospital's base rate multiplied by the DRG relative weight.
What is the FY2027 relative weight for DRG 478?
The FY2027 relative weight is 2.4340 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 2.4590, a change of -1.0%.
What is the average length of stay for DRG 478?
CMS reports a geometric mean length of stay of 5.3 days and an arithmetic mean of 6.5 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 478?
DRG 477 (Biopsies of Musculoskeletal System and Connective Tissue with MCC or Insertion of Antibiotic-eluting Bone Void Filler, weight 3.4030); DRG 479 (Biopsies of Musculoskeletal System and Connective Tissue without CC/MCC, weight 1.8530). The family's weights range from 1.8530 to 3.4030, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 478?
DRG 478 is reached when the stay carries a secondary diagnosis from the CMS Complication or Comorbidity list but none from the MCC list. Common CC captures include chronic kidney disease stage 3 and above, uncontrolled diabetes with manifestations, malnutrition of specified severity and heart failure of a stated type. Each must be documented by the treating clinician and show clinical relevance in the record; a condition listed only in the problem list without assessment is the most frequent reason a CC is removed on audit and the stay drops to the base DRG.
Which codes group to DRG 478?
The v44 Definitions Manual lists 431 operating room procedures codes for this group. Examples from the operating room procedures list: 0MJX0ZZ (Inspection of Upper Bursa and Ligament, Open Approach); 0MJX4ZZ (Inspection of Upper Bursa and Ligament, Percutaneous Endoscopic Approach); 0MJY0ZZ (Inspection of Lower Bursa and Ligament, Open Approach); 0MJY4ZZ (Inspection of Lower Bursa and Ligament, Percutaneous Endoscopic Approach).
Is DRG 478 a post-acute transfer DRG?
Yes. CMS flags DRG 478 under the post-acute care transfer policy, so a discharge to a qualifying post-acute setting before the geometric mean length of stay is paid a per-diem amount rather than the full DRG payment. It is also a special-pay DRG.
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-01. Verify against the primary file before billing or contracting decisions.
- IPPS FY2027 Final Rule Table 5 (CMS-1849-F)Version v44 FY2027 · effective 2026-10-01 · file CMS-1849-F Table 5.txtSHA-256 01003dd571c1e2f5…
- IPPS FY2026 Final Rule Table 5 (CMS-1833-F)Version v43 FY2026 · effective 2025-10-01 · file CMS-1833-F Table 5.txtSHA-256 bf8c390d14b3cd3e…
- ICD-10 MS-DRG Definitions Manual v44 (text)Version v44 · effective 2026-10-01 · file fy2027-fr-icd10-ms-drg-definitions-manual-files-v44.zipSHA-256 ae4f6c11727fe91f…
Disclaimer
This page is an operational reference compiled from the CMS IPPS FY2027 final rule (Table 5) and the v44 ICD-10 MS-DRG Definitions Manual. Relative weights are national factors; actual payment depends on each hospital's wage-adjusted base rate, add-ons, outliers and transfer adjustments. Nothing here is legal, clinical or billing advice; verify grouping against your encoder and the published CMS files.