Key facts for DRG 855
- FY2027 relative weight
- 1.4500
- Higher than 41% of all MS-DRGs
- Change vs FY2026
- -3.1%
- FY2026 weight 1.4970
- Geometric mean LOS
- 3.2 days
- Arithmetic mean 4.1 days
- MDC
- 18
- Infectious and Parasitic Diseases, Systemic or Unspecified Sites
- Severity level
- without CC or MCC
- Transfer policy
- Post-acute transfer DRG
TL;DR
MS-DRG 855 is a surgical group in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites) at the base severity level of its family. CMS assigns it a FY2027 relative weight of 1.4500 with a geometric mean length of stay of 3.2 days and an arithmetic mean of 4.1. Its weight moved down 3.1% from FY2026 (1.4970). That weight is higher than 41% of all surgical and medical MS-DRGs. Its CC/MCC family (DRG 853, DRG 854) spans weights 1.4500 to 4.9310.
What changed from FY2026 to FY2027
CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 855 the FY2027 relative weight is 1.4500 against 1.4970 in FY2026, a fall of 3.14%, which exceeds the 2% threshold worth re-checking in contract models.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 1.4970 | 1.4500 | -0.0470 |
| Geometric mean LOS (days) | 2.9 | 3.2 | +0.3 |
| Arithmetic mean LOS (days) | 3.7 | 4.1 | +0.4 |
CC and MCC family
DRG 855 shares its base definition with 2 other MS-DRGs split by severity. The family's weights span 1.4500 to 4.9310, a 3.40× spread, which is the payment effect of documenting qualifying complications and comorbidities.
Grouper logic (v44 Definitions Manual)
The Definitions Manual assigns DRG 855 through the MDC 18 principal-diagnosis table and the operating-room procedure hierarchy rather than a DRG-specific code list. See the manual chapter for MDC 18.
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 18 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 855 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 855
What is MS-DRG 855?
MS-DRG 855 is "Infectious and Parasitic Diseases with O.R. Procedures without CC/MCC", a surgical Medicare Severity Diagnosis-Related Group in MDC 18, Infectious and Parasitic Diseases, Systemic or Unspecified Sites. 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 855?
The FY2027 relative weight is 1.4500 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 1.4970, a change of -3.1%.
What is the average length of stay for DRG 855?
CMS reports a geometric mean length of stay of 3.2 days and an arithmetic mean of 4.1 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 855?
DRG 853 (Infectious and Parasitic Diseases with O.R. Procedures with MCC, weight 4.9310); DRG 854 (Infectious and Parasitic Diseases with O.R. Procedures with CC, weight 2.0090). The family's weights range from 1.4500 to 4.9310, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 855?
DRG 855 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.
Is DRG 855 a post-acute transfer DRG?
Yes. CMS flags DRG 855 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.