Key facts for DRG 179
- FY2027 relative weight
- 0.7340
- Higher than 7% of all MS-DRGs
- Change vs FY2026
- -2.8%
- FY2026 weight 0.7550
- Geometric mean LOS
- 2.4 days
- Arithmetic mean 3.0 days
- MDC
- 04
- Assignment of Diagnosis Codes
- Severity level
- without CC or MCC
- Transfer policy
- Post-acute transfer DRG
TL;DR
MS-DRG 179 is a medical group in MDC 04 (Assignment of Diagnosis Codes) at the base severity level of its family. CMS assigns it a FY2027 relative weight of 0.7340 with a geometric mean length of stay of 2.4 days and an arithmetic mean of 3.0. Its weight moved down 2.8% from FY2026 (0.7550). That weight is higher than 7% of all medical and surgical MS-DRGs. Its CC/MCC family (DRG 177, DRG 178) spans weights 0.7340 to 1.6090. The v44 Definitions Manual assigns it through 75 principal diagnosis codes.
What changed from FY2026 to FY2027
CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 179 the FY2027 relative weight is 0.7340 against 0.7550 in FY2026, a fall of 2.78%, which exceeds the 2% threshold worth re-checking in contract models.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 0.7550 | 0.7340 | -0.0210 |
| Geometric mean LOS (days) | 2.4 | 2.4 | +0.0 |
| Arithmetic mean LOS (days) | 3.0 | 3.0 | +0.0 |
CC and MCC family
DRG 179 shares its base definition with 2 other MS-DRGs split by severity. The family's weights span 0.7340 to 1.6090, a 2.19× spread, which is the payment effect of documenting qualifying complications and comorbidities.
Grouper logic (v44 Definitions Manual)
Principal Diagnosis: 75 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| J1000 | Influenza due to other identified influenza virus with unspecified type of pneumonia |
| J1001 | Influenza due to other identified influenza virus with the same other identified influenza virus pneumonia |
| J1008 | Influenza due to other identified influenza virus with other specified pneumonia |
| J1100 | Influenza due to unidentified influenza virus with unspecified type of pneumonia |
| J1108 | Influenza due to unidentified influenza virus with specified pneumonia |
| A481 | Legionnaires' disease |
| J150 | Pneumonia due to Klebsiella pneumoniae |
| J151 | Pneumonia due to Pseudomonas |
| J1520 | Pneumonia due to staphylococcus, unspecified |
| J15211 | Pneumonia due to Methicillin susceptible Staphylococcus aureus |
| J15212 | Pneumonia due to Methicillin resistant Staphylococcus aureus |
| J1529 | Pneumonia due to other staphylococcus |
Documentation and denial exposure
As a medical DRG, assignment depends on the principal diagnosis sequenced from the attending's documentation; a secondary condition sequenced first, or a symptom code in place of the confirmed diagnosis, changes the MDC or the DRG. 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 179 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 179
What is MS-DRG 179?
MS-DRG 179 is "Respiratory Infections and Inflammations without CC/MCC", a medical Medicare Severity Diagnosis-Related Group in MDC 04, Assignment of Diagnosis Codes. 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 179?
The FY2027 relative weight is 0.7340 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 0.7550, a change of -2.8%.
What is the average length of stay for DRG 179?
CMS reports a geometric mean length of stay of 2.4 days and an arithmetic mean of 3.0 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 179?
DRG 177 (Respiratory Infections and Inflammations with MCC, weight 1.6090); DRG 178 (Respiratory Infections and Inflammations with CC, weight 0.9740). The family's weights range from 0.7340 to 1.6090, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 179?
DRG 179 is the base-severity assignment: no secondary diagnosis on the CC or MCC lists was coded, or the only ones present are excluded for this principal diagnosis. Revenue-integrity review here looks for undercapture, meaning conditions treated during the stay (electrolyte disorders, specified anemia, acute blood loss, pressure injuries present on admission) that were never documented to the specificity the lists require. A compliant query to the attending, not a coder assumption, is the only way to move a stay to the CC or MCC sibling.
Which codes group to DRG 179?
The v44 Definitions Manual lists 75 principal diagnosis codes for this group. Examples from the principal diagnosis list: J1000 (Influenza due to other identified influenza virus with unspecified type of pneumonia); J1001 (Influenza due to other identified influenza virus with the same other identified influenza virus pneumonia); J1008 (Influenza due to other identified influenza virus with other specified pneumonia); J1100 (Influenza due to unidentified influenza virus with unspecified type of pneumonia).
Is DRG 179 a post-acute transfer DRG?
Yes. CMS flags DRG 179 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.
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.