864 MS-DRG: FEVER AND INFLAMMATORY CONDITIONS
MS-DRG 864 groups Medicare inpatient hospital stays for: FEVER AND INFLAMMATORY CONDITIONS. This is a medical MS-DRG. It falls under MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites).
Payment & Classification Data
Official CMS values from the FY2027 IPPS Final Rule Table 5.
| Major Diagnostic Category | MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites |
| DRG Type | Medical |
| Severity Level | N/A |
| Relative Weight | 0.8551 |
| Relative Weight (10% Cap Applied) | 0.8551 |
| Geometric Mean Length of Stay | 2.5 days |
| Arithmetic Mean Length of Stay | 3.2 days |
| Post-Acute Transfer DRG | No |
| Special Pay Transfer DRG | No |
Defining Codes (FY2027)
8 diagnosis codes can drive assignment here: R50.2, R50.81, R50.82, R50.83, R50.84, R50.9, R65.10, R65.11.
From the CMS MS-DRG Definitions Manual (Appendices B and E). Assignment also depends on severity, discharge status and the rest of the claim.
Contextual Map
Every relationship of 864 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.
Major Diagnostic Category
- MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC]— CMS MS-DRG Definitions Manual · FY2027
Defining diagnoses
- R50.2 — Drug induced fever[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R50.81 — Fever presenting with conditions classified elsewhere[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R50.82 — Postprocedural fever[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R50.83 — Postvaccination fever[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R50.84 — Febrile nonhemolytic transfusion reaction[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R50.9 — Fever, unspecified[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R65.10 — Systemic inflammatory response syndrome (SIRS) of non-infectious origin without acute organ dysfunction[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
- R65.11 — Systemic inflammatory response syndrome (SIRS) of non-infectious origin with acute organ dysfunction[Grouper diagnosis]— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
Read from: CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44. All data sources · How to read the labels · How MedCoder verifies its implementation
Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources