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_HCC228 | 0.252 |
| Community, non-dual, disabled | CND_HCC228 | 0.254 |
| Community, full-benefit dual, aged | CFA_HCC228 | 0.493 |
| Community, full-benefit dual, disabled | CFD_HCC228 | 0.517 |
| Community, partial-benefit dual, aged | CPA_HCC228 | 0.324 |
| Community, partial-benefit dual, disabled | CPD_HCC228 | 0.407 |
| Long-term institutional | INS_HCC228 | 0.310 |
Hierarchy
Hierarchical condition categories pay only the most severe manifestation of a disease. HCC 228 is the most severe category in its hierarchy. When HCC 228 is present it drops HCC 229 (Unstable Angina and Other Acute Ischemic Heart Disease), so documenting the less severe condition alongside it adds nothing to payment but still matters for the clinical record.
ICD-10-CM codes that map to HCC 228
18 codes map to this category in the PY2027 initial mapping, concentrated in the I21 (13), I22 (5) 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 |
|---|---|
| I2101 | ST elevation (STEMI) myocardial infarction involving left main coronary artery |
| I2102 | ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery |
| I2109 | ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall |
| I2111 | ST elevation (STEMI) myocardial infarction involving right coronary artery |
| I2119 | ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall |
| I2121 | ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery |
| I2129 | ST elevation (STEMI) myocardial infarction involving other sites |
| I213 | ST elevation (STEMI) myocardial infarction of unspecified site |
| I214 | Non-ST elevation (NSTEMI) myocardial infarction |
| I219 | Acute myocardial infarction, unspecified |
| I21A1 | Myocardial infarction type 2 |
| I21A9 | Other myocardial infarction type |
| I21B | Myocardial infarction with coronary microvascular dysfunction |
| I220 | Subsequent ST elevation (STEMI) myocardial infarction of anterior wall |
| I221 | Subsequent ST elevation (STEMI) myocardial infarction of inferior wall |
| I222 | Subsequent non-ST elevation (NSTEMI) myocardial infarction |
| I228 | Subsequent ST elevation (STEMI) myocardial infarction of other sites |
| I229 | Subsequent ST elevation (STEMI) myocardial infarction of unspecified site |
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 |
|---|---|
| 86 | 18 |
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 228?
18 ICD-10-CM codes map to HCC 228 in the CMS PY2027 initial mapping, for example I2101 ST elevation (STEMI) myocardial infarction involving left main coronary artery; I2102 ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery; I2109 ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall; I2111 ST elevation (STEMI) myocardial infarction involving right coronary artery. 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 228 add to a risk score?
The V28 relative factor for HCC 228 is 0.252 for a community, non-dual, aged beneficiary, 0.493 for full-benefit dual aged, 0.254 for non-dual disabled and 0.310 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 228 count together with related categories?
No. Within a hierarchy only the most severe category is paid. HCC 228 is the most severe category in its hierarchy, and it drops HCC 229 when it is present.
What has to be documented for HCC 228 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.