Relative factors by segment
Each segment is a separate regression; the factor is added to the beneficiary's demographic factors and other categories, then normalized and reduced by the coding intensity adjustment before it meets the plan's base rate. A factor of 1.000 equals the expected cost of an average beneficiary.
| Segment | Model code | Relative factor |
|---|---|---|
| Community, non-dual, aged | CNA_HCC454 | 1.068 |
| Community, non-dual, disabled | CND_HCC454 | 0.452 |
| Community, full-benefit dual, aged | CFA_HCC454 | 1.326 |
| Community, full-benefit dual, disabled | CFD_HCC454 | 0.608 |
| Community, partial-benefit dual, aged | CPA_HCC454 | 1.338 |
| Community, partial-benefit dual, disabled | CPD_HCC454 | 0.416 |
| Long-term institutional | INS_HCC454 | 1.596 |
Hierarchy
HCC 454 is not part of a hierarchy: it is paid whenever a mapped diagnosis is documented, independently of the beneficiary's other categories.
ICD-10-CM codes that map to HCC 454
14 codes map to this category in the PY2027 initial mapping, concentrated in the T86 (6), D89 (4), Z94 (2), M31 (1), Z48 (1) code families. Descriptions are the CMS mapping descriptions for the FY2026 code set; a code that is deleted or split in the October code update stays valid for dates of service before the change.
| ICD-10-CM | Description |
|---|---|
| D89810 | Acute graft-versus-host disease |
| D89811 | Chronic graft-versus-host disease |
| D89812 | Acute on chronic graft-versus-host disease |
| D89813 | Graft-versus-host disease, unspecified |
| M3111 | Hematopoietic stem cell transplantation-associated thrombotic microangiopathy [HSCT-TMA] |
| T8600 | Unspecified complication of bone marrow transplant |
| T8601 | Bone marrow transplant rejection |
| T8602 | Bone marrow transplant failure |
| T8603 | Bone marrow transplant infection |
| T8609 | Other complications of bone marrow transplant |
| T865 | Complications of stem cell transplant |
| Z48290 | Encounter for aftercare following bone marrow transplant |
| Z9481 | Bone marrow transplant status |
| Z9484 | Stem cells transplant status |
Where these codes sat in the V22 model
The V28 recalibration renumbered and regrouped categories; this table shows which legacy V22 categories the same ICD-10 codes belonged to, which is the quickest way to reconcile a V22-era HCC gap list with the current model.
| V22 HCC | Codes |
|---|---|
| 186 | 10 |
| 47 | 4 |
Capturing and defending the category
A category counts for a payment year when a mapped diagnosis is documented at least once during the data collection year by an acceptable provider type at a face-to-face or audio-video encounter, and when the note shows the condition was monitored, evaluated, assessed or treated. Chronic conditions do not carry forward: a category that is not re-documented in the year drops out of the score, which is why annual wellness visits and problem-list reconciliation are where most recapture happens. Risk adjustment data validation audits sample enrollees and ask for the medical record behind each submitted category; an unsupported category is removed and, under the extrapolation rules, the error rate is applied across the contract. The QuickIntell risk adjustment product surfaces suspected and unsupported categories from the chart, and the HCC hub lists every V28 category with its factor and code count.
Frequently asked questions
Which ICD-10 codes map to HCC 454?
14 ICD-10-CM codes map to HCC 454 in the CMS PY2027 initial mapping, for example D89810 Acute graft-versus-host disease; D89811 Chronic graft-versus-host disease; D89812 Acute on chronic graft-versus-host disease; D89813 Graft-versus-host disease, unspecified. The full list is on this page; a code counts only when it is documented at a face-to-face or video encounter in the data collection year and supported by the record.
How much does HCC 454 add to a risk score?
The V28 relative factor for HCC 454 is 1.068 for a community, non-dual, aged beneficiary, 1.326 for full-benefit dual aged, 0.452 for non-dual disabled and 1.596 for long-term institutional members. A factor of 1.000 equals the expected annual cost of an average beneficiary, so the category's share of the payment follows the plan's base rate for that segment.
Does HCC 454 count together with related categories?
HCC 454 is not part of a hierarchy, so it is paid whenever it is documented regardless of which other categories the beneficiary has.
What has to be documented for HCC 454 to be valid?
The diagnosis must be recorded by an acceptable provider type during a face-to-face or audio-video encounter in the service year, with the note showing that the condition was monitored, evaluated, assessed or treated. Risk adjustment data validation audits recover payment for categories the record does not support, so the code on the claim and the assessment in the note must match.
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-02. Verify against the primary file before billing or contracting decisions.
- ICD-10-CM to CMS-HCC V28 mappings, payment year 2027 initialVersion PY2027 initial ICD-10-CM mappings (dates of service 2026) · effective 2027-01-01 · file 2027 Initial ICD-10-CM Mappings.csvSHA-256 9c260b06d0dd2806…
- CMS-HCC V28 model software: labels, hierarchies and relative factorsVersion CMS-HCC V28 software V2826.115.T2 (PY2027 initial) · effective 2027-01-01 · file C2824T2N.csvSHA-256 20f38d537493b41c…
Disclaimer
Relative factors and mappings are reproduced from the CMS risk adjustment model files as an operational reference. Payment depends on the plan's base rate, normalization, the coding intensity adjustment and the enrollee's segment. Not legal, clinical or billing advice.