MS-DRG · FY 2026 v43.0

MS-DRG 864 – Fever and Inflammatory Conditions

A Medical DRG in MDC 18 (Infectious & Parasitic Diseases, Systemic or Unspecified Sites). Inpatient cases group to DRG 864 when the ICD-10-CM principal diagnosis is one of the 8 codes listed below. Its FY 2026 relative weight is 0.8877 with a geometric mean length of stay of 2.6 days.

Medical DRG – assigned by principal diagnosis✓ Official CMS v43.0 dataset
0.8877
Relative Weight
2.6
Geometric Mean LOS (days)
3.2
Arithmetic Mean LOS (days)
8
Principal Diagnosis Codes
How a case is assigned to DRG 864

The grouper first assigns the case to MDC 18 from the principal diagnosis and finds no qualifying operating-room procedure (this is a Medical DRG; ICD-10-PCS codes do not drive assignment here).

ICD-10-CM

Principal Diagnosis Codes 8 codes · 2 categories

R50 Fever of other and unknown origin6 codes
  • R50.2 Drug induced fever
  • R50.81 Fever presenting with conditions classified elsewhere
  • R50.82 Postprocedural fever
  • R50.83 Postvaccination fever
  • R50.84 Febrile nonhemolytic transfusion reaction
  • R50.9 Fever, unspecified
R65 Symptoms and signs specifically associated with systemic inflammation and infection2 codes
  • R65.10 Systemic inflammatory response syndrome (SIRS) of non-infectious origin without acute organ dysfunction
  • R65.11 Systemic inflammatory response syndrome (SIRS) of non-infectious origin with acute organ dysfunction
ICD-10-PCS

Procedure Codes

Procedure codes do not drive assignment for this DRG. DRG 864 is a Medical DRG, assigned from the principal diagnosis above.

Frequently Asked Questions

What is MS-DRG 864?

MS-DRG 864 (Fever and Inflammatory Conditions) is a medical DRG in MDC 18 (Infectious & Parasitic Diseases, Systemic or Unspecified Sites). Its FY 2026 relative weight is 0.8877 with a geometric mean length of stay of 2.6 days.

How many diagnosis codes group to DRG 864?

8 ICD-10-CM principal diagnosis codes group to this DRG, spanning 2 three-character categories.

What is the relative weight of DRG 864?

The FY 2026 relative weight of this DRG is 0.8877, meaning reimbursement of roughly 0.89 times the average Medicare inpatient case. Multiply by a hospital's blended base rate for the approximate payment.

← PreviousDRG 863 – Postoperative and Post-Traumatic Infections without MCC
Source: CMS ICD-10 MS-DRG v43.0 Definitions Manual and the FY 2026 IPPS Final Rule (Table 5), effective October 1, 2025 through September 30, 2026. We publish the DRG assignments as CMS defines them and add the navigation, search, and code links.