Key facts for DRG 843
- FY2027 relative weight
- 1.9450
- Higher than 61% of all MS-DRGs
- Change vs FY2026
- -2.5%
- FY2026 weight 1.9950
- Geometric mean LOS
- 5.3 days
- Arithmetic mean 7.3 days
- MDC
- 17
- Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms
- Severity level
- with MCC (major complication or comorbidity)
- Transfer policy
- Not a transfer DRG
TL;DR
MS-DRG 843 is a medical group in MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms) at the highest-severity level of its family. CMS assigns it a FY2027 relative weight of 1.9450 with a geometric mean length of stay of 5.3 days and an arithmetic mean of 7.3. Its weight moved down 2.5% from FY2026 (1.9950). That weight is higher than 61% of all medical and surgical MS-DRGs. Its CC/MCC family (DRG 844, DRG 845) spans weights 0.8440 to 1.9450. The v44 Definitions Manual assigns it through 110 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 843 the FY2027 relative weight is 1.9450 against 1.9950 in FY2026, a fall of 2.51%, which exceeds the 2% threshold worth re-checking in contract models.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 1.9950 | 1.9450 | -0.0500 |
| Geometric mean LOS (days) | 5.4 | 5.3 | -0.1 |
| Arithmetic mean LOS (days) | 7.5 | 7.3 | -0.2 |
CC and MCC family
DRG 843 shares its base definition with 2 other MS-DRGs split by severity. The family's weights span 0.8440 to 1.9450, a 2.30× spread, which is the payment effect of documenting qualifying complications and comorbidities.
| DRG | Title | FY2027 weight | GMLOS |
|---|---|---|---|
| 843 | Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC | 1.9450 | 5.3 |
| 844 | Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with CC | 1.2560 | 3.7 |
| 845 | Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses without CC/MCC | 0.8440 | 2.3 |
Grouper logic (v44 Definitions Manual)
Principal Diagnosis: 110 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| C37 | Malignant neoplasm of thymus |
| C457 | Mesothelioma of other sites |
| C459 | Mesothelioma, unspecified |
| C480 | Malignant neoplasm of retroperitoneum |
| C7640 | Malignant neoplasm of unspecified upper limb |
| C7641 | Malignant neoplasm of right upper limb |
| C7642 | Malignant neoplasm of left upper limb |
| C7650 | Malignant neoplasm of unspecified lower limb |
| C7651 | Malignant neoplasm of right lower limb |
| C7652 | Malignant neoplasm of left lower limb |
| C768 | Malignant neoplasm of other specified ill-defined sites |
| C7983 | Secondary malignant neoplasm of oral cavity |
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 843 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 843
What is MS-DRG 843?
MS-DRG 843 is "Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC", a medical Medicare Severity Diagnosis-Related Group in MDC 17, Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms. 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 843?
The FY2027 relative weight is 1.9450 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 1.9950, a change of -2.5%.
What is the average length of stay for DRG 843?
CMS reports a geometric mean length of stay of 5.3 days and an arithmetic mean of 7.3 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 843?
DRG 844 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with CC, weight 1.2560); DRG 845 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses without CC/MCC, weight 0.8440). The family's weights range from 0.8440 to 1.9450, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 843?
DRG 843 requires at least one secondary diagnosis on the CMS Major Complication or Comorbidity list, documented as present and clinically addressed during the stay (monitored, evaluated, treated or extending the stay). Conditions such as acute respiratory failure, severe sepsis or acute kidney injury with specified cause qualify only when the attending's note states the diagnosis itself, not just the lab values. Recovery auditors downgrade this group to the CC or base level when the MCC rests on an unconfirmed query or a resolved historical condition, so the query response and the discharge summary must agree.
Which codes group to DRG 843?
The v44 Definitions Manual lists 110 principal diagnosis codes for this group. Examples from the principal diagnosis list: C37 (Malignant neoplasm of thymus); C457 (Mesothelioma of other sites); C459 (Mesothelioma, unspecified); C480 (Malignant neoplasm of retroperitoneum).
Is DRG 843 a post-acute transfer DRG?
No. DRG 843 is not on the FY2027 post-acute care transfer list, so the transfer per-diem policy does not apply to it.
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.