MS-DRG 866: VIRAL ILLNESS WITHOUT MCC
MS-DRG 866 is viral illness without mcc, in MDC 18 (a medical DRG), at the without-CC/MCC level. Its FY2027 relative weight is 0.8692, so a case here pays less than the average Medicare inpatient stay (weight 1.0), with a geometric mean length of stay of 2.70 days. 141 ICD-10-CM principal diagnoses group into MS-DRGs 865–866 under the CMS definitions manual; the most-searched are listed below.
FY2027 payment factors
- Relative weight
- 0.8692
- Geometric mean LOS
- 2.70
- Arithmetic mean LOS
- 3.50
- Post-acute transfer
- No
Principal diagnoses that group to MS-DRGs 865–866
From the CMS MS-DRG definitions manual’s principal-diagnosis index: 141 ICD-10-CM codes route here, and the CC/MCC status of the secondary diagnoses decides which of 865–866 the case lands in. The 24 most-searched:
- Z21Asymptomatic human immunodeficiency virus [HIV] infection status
- B34.9Viral infection, unspecified
- B08.4Enteroviral vesicular stomatitis with exanthem
- B09Unspecified viral infection characterized by skin and mucous membrane lesions
- B33.8Other specified viral diseases
- B25.9Cytomegaloviral disease, unspecified
- B27.90Infectious mononucleosis, unspecified without complication
- B34.8Other viral infections of unspecified site
- B97.4Respiratory syncytial virus as the cause of diseases classified elsewhere
- B97.89Other viral agents as the cause of diseases classified elsewhere
- A74.9Chlamydial infection, unspecified
- B02.8Zoster with other complications
- B34.2Coronavirus infection, unspecified
- B97.7Papillomavirus as the cause of diseases classified elsewhere
- A90Dengue fever [classical dengue]
- A91Dengue hemorrhagic fever
- A92.30West Nile virus infection, unspecified
- A92.39West Nile virus infection with other complications
- A92.5Zika virus disease
- A99Unspecified viral hemorrhagic fever
- B00.89Other herpesviral infection
- B01.9Varicella without complication
- B04Monkeypox
- B05.9Measles without complication
117 more codes group here. Open any code above for its full hierarchy, or check a whole claim in the free DRG calculator.
The severity splits
Same base DRG, split by whether a secondary diagnosis is a CC or MCC. The last column is the weight change from MS-DRG 866.
| 865 | VIRAL ILLNESS WITH MCC | 1.3485 | +0.4793 |
| 866 | VIRAL ILLNESS WITHOUT MCC | 0.8692 |
All FY2027 MS-DRGs · MDC 18