Condition guide
Stroke and Cerebrovascular Disease HCC Coding Guide
Stroke and Cerebrovascular Disease (e.g. I63.9) maps to HCC 249 (Ischemic or Unspecified Stroke) under CMS-HCC V28. Its source-labeled community non-dual aged reference coefficient is 0.239. This is not a member total; full contribution depends on hierarchy, cleanup, interactions, member context, and model year. I69.320, aphasia following cerebral infarction, is non-HCC under V28. It can also map to HCC 253 (Hemiplegia/Hemiparesis) when the documentation supports those manifestations.
Quick Facts
HCC Categories
HCC 253, Hemiplegia/Hemiparesis
HCC 249, Ischemic or Unspecified Stroke
RAF Weight Range
0.239 to 0.387
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
7 ICD-10 codes map to payment HCCs
What HCC category does Stroke and Cerebrovascular Disease map to under V28?
Under CMS-HCC V28, ischemic stroke codes (I63.x) map to HCC 249. When documentation supports lasting hemiplegia or hemiparesis, the sequela codes (I69.35x) map to HCC 253. Distinguish acute stroke from sequelae and history, then apply the complete diagnosis set, hierarchy, cleanup, interactions, and member-segment coefficient table. Do not add category coefficients from the code pair alone.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| I63.9 | Cerebral infarction, unspecified | Yes | HCC 249 |
| I63.50 | Cerebral infarction due to unspecified occlusion or stenosis of unspecified cerebral artery | Yes | HCC 249 |
| I63.511 | Cerebral infarction due to unspecified occlusion or stenosis of right middle cerebral artery | Yes | HCC 249 |
| I63.512 | Cerebral infarction due to unspecified occlusion or stenosis of left middle cerebral artery | Yes | HCC 249 |
| I63.411 | Cerebral infarction due to embolism of right middle cerebral artery | Yes | HCC 249 |
| I69.351 | Hemiplegia and hemiparesis following cerebral infarction affecting right dominant side | Yes | HCC 253 |
| I69.320 | Aphasia following cerebral infarction | Yes | No HCC (not risk-adjusting under V28) |
| G45.9 | Transient cerebral ischemic attack, unspecified | Yes | No HCC (not risk-adjusting under V28) |
| I69.354 | Hemiplegia and hemiparesis following cerebral infarction affecting left non-dominant side | Yes | HCC 253 |
| Z86.73 | Personal history of transient ischemic attack and cerebral infarction without residual deficits | Yes | No HCC (not risk-adjusting under V28) |
Displayed numbers are source-labeled community non-dual aged reference coefficients from CMS-HCC V28, not member totals.
Verify Stroke and Cerebrovascular Disease against the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coder workflow notes
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Documentation Tips
Document the type of stroke: ischemic (I63), hemorrhagic (I61-I62), or TIA (G45), each has different HCC implications.
Specify the arterial territory: middle cerebral artery, anterior cerebral artery, posterior cerebral artery, vertebrobasilar.
Document the mechanism: thrombotic, embolic, lacunar, this determines the 4th character of the I63 code.
Specify laterality (right, left) for the affected arterial territory and any resulting deficits.
For post-stroke patients, document specific sequelae at each encounter: hemiplegia, aphasia, dysphagia, cognitive deficits.
Distinguish between acute stroke (I63.x, for the initial event), sequelae (I69.3x, for lasting deficits), and personal history (Z86.73, when fully resolved).
Document NIH Stroke Scale (NIHSS) score when available to support severity documentation.
Common Coding Mistakes
Coding acute stroke (I63.x) at follow-up visits when the patient should be coded with sequelae (I69.3x) or personal history (Z86.73).
Failing to capture specific neurological sequelae (hemiplegia, aphasia, dysphagia) as separate codes alongside the stroke sequelae code.
Not specifying the arterial territory and laterality when imaging or clinical findings clearly indicate the location.
Confusing TIA (G45.x) with completed stroke (I63.x), TIAs do not result in permanent infarction and map differently.
Using history of stroke (Z86.73) when the patient has active, ongoing neurological deficits that should be coded as sequelae.
V24 to V28 Changes
Under V28, ischemic stroke (I63.x) lands in HCC 249 (Ischemic or Unspecified Stroke), distinct from the category numbering used in the older V24 model. The bigger takeaway for coders is how the manifestations split out: lasting deficits do not ride along with the stroke HCC. Post-stroke hemiplegia and hemiparesis sequelae (I69.35x), like standalone hemiplegia (G81.x), map to their own category, HCC 253 (Hemiplegia/Hemiparesis). So a patient with a prior infarction and persistent weakness can support two HCCs: 249 for the stroke when still acute, and 253 for the deficit. That makes coding each documented sequela separately, not just the stroke itself, essential to a complete RAF picture.
Related Conditions
Related references
Sources
Displayed numbers are source-labeled community non-dual aged reference coefficients from CMS-HCC V28, not member totals.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed September 5, 2026.
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