Dementia HCC Coding Guide: Alzheimer's and Vascular Dementia

Quick Answer

Dementia maps to HCC categories 125, 126, and 127 under V28, stratified by severity, with RAF weights around 0.341 or higher depending on the severity tier. The key codes are F01.x (vascular dementia), F02.x (dementia in diseases classified elsewhere, including Alzheimer's-related), F03.x (unspecified dementia), and G30.x (Alzheimer's disease). Under V28, CMS restructured the dementia HCCs to emphasize severity — coders now need documentation of behavioral disturbance and severity level, not just the dementia type. The most impactful coding change: dementia "without behavioral disturbance" and "with behavioral disturbance" now map to different HCC tiers, making behavioral documentation essential for accurate risk adjustment.

Dementia in the Medicare Population

Dementia affects approximately 6.7 million Americans aged 65 and older, with prevalence increasing sharply with age. In the Medicare Advantage population, dementia is one of the most expensive conditions to manage — driving costs through skilled nursing facility stays, home health services, medication management, caregiver support, and frequent hospitalizations for comorbid conditions.

For risk adjustment purposes, dementia is a high-value HCC category. Accurate coding requires understanding the ICD-10 code families, the V28 HCC structure, and the documentation requirements for severity and behavioral disturbance.

Dementia ICD-10 Code Families

Vascular Dementia (F01.x)

Vascular dementia results from cerebrovascular disease — strokes, TIAs, or chronic small vessel ischemic disease that damages brain tissue and causes cognitive decline.

Dementia in Other Diseases (F02.x) — Including Alzheimer's

F02.x codes are used for dementia that occurs as a manifestation of another documented disease. The most common use is for Alzheimer's disease dementia, where F02.x is coded alongside G30.x (Alzheimer's disease).

Unspecified Dementia (F03.x)

F03.x codes are used when the type of dementia (vascular, Alzheimer's, etc.) is not documented. The same severity and behavioral disturbance structure applies.

Alzheimer's Disease (G30.x)

G30.x codes classify the Alzheimer's disease itself and are coded in addition to the F02.x dementia code. The combination of G30.x + F02.x captures both the underlying disease and the dementia manifestation.

Coding rule: When a patient has Alzheimer's disease with dementia, code both the G30.x (Alzheimer's disease) and the F02.x (dementia manifestation). The G30.x code is sequenced first as the underlying disease, followed by the F02.x code with the appropriate severity and behavioral disturbance designation.

V28 Changes to Dementia HCC Categories

V28 fundamentally restructured how dementia is categorized for risk adjustment. Under V24, dementia mapped primarily based on type. Under V28, the stratification emphasizes severity and behavioral disturbance — the full mapping tables are published in the CMS 2026 risk-adjustment model software and ICD-10 mappings:

The V28 Dementia HCC Hierarchy

The Hierarchy Rule

HCC 125 trumps HCC 126, which trumps HCC 127. If a patient qualifies for both HCC 125 and HCC 127, only HCC 125 is counted. Coders should capture the highest-supported severity and behavioral status.

Documentation Requirements for Dementia Coding

Severity Documentation

Under V28, severity determines the HCC tier. Providers should document severity using standard clinical terms:

Cognitive assessment tools that support severity:

Behavioral Disturbance Documentation

Behavioral disturbance is the second axis of V28 dementia coding and has a direct impact on HCC tier assignment. Providers should document:

When behavioral disturbance is present, the code shifts from "without behavioral disturbance" to "with behavioral disturbance" — which often moves the patient to a higher HCC tier.

Common Dementia Coding Errors

Error 1: Missing the Behavioral Disturbance Code

A patient with documented moderate Alzheimer's dementia and "occasional agitation requiring redirection" is coded as F02.B0 (moderate, without behavioral disturbance) instead of F02.B11 (moderate, with agitation). This drops the patient from HCC 125 to HCC 126.

Error 2: Not Coding Both G30.x and F02.x for Alzheimer's

A patient with documented Alzheimer's disease is coded with only G30.9, missing the F02.x code entirely. Or conversely, coded with only F02.80, missing the G30.x code. Both codes are required for Alzheimer's dementia.

Error 3: Using "History of Dementia" Language

Dementia does not resolve. A patient diagnosed with dementia has dementia — it is a current, chronic, progressive condition. "History of dementia" or "h/o Alzheimer's" is inappropriate language that could cause coders to skip the diagnosis. Providers should document dementia as a current active condition at every encounter.

Error 4: Failing to Specify Severity

"Dementia" without severity forces the coder to F03.90 (unspecified severity, without behavioral disturbance) — HCC 126. If the patient has moderate or severe dementia based on cognitive assessment, the documentation should state it explicitly to support the higher HCC tier.

Dementia Medications as Diagnostic Signals

Use the Drug Reference tool to identify patients who may have undocumented or undercoded dementia. Key medications:

A patient on donepezil without a coded dementia diagnosis is a missed HCC. A patient on memantine coded with "mild" dementia should be reviewed — memantine is indicated for moderate-to-severe dementia, which suggests the severity documentation may need updating.

Using HCC Buddy for Dementia Code Lookups

Type any F01, F02, F03, or G30 code into the ICD-10 Encoder to see the exact V28 HCC mapping. This is particularly important for dementia because the behavioral disturbance and severity axes create dozens of code variations, each mapping to a different HCC tier.

The RAF Calculator lets you model the impact of different dementia HCC tiers on a patient's total score. Compare HCC 125 versus HCC 126 versus HCC 127 to see the RAF coefficient difference and understand the documentation stakes.

Key Takeaways

1. V28 stratifies dementia by severity and behavioral disturbance — both dimensions affect the HCC tier (125, 126, or 127).

2. Behavioral disturbance documentation moves patients to higher HCC tiers — agitation, psychotic features, wandering, and mood disturbance all count.

3. Alzheimer's requires dual coding — G30.x (the disease) plus F02.x (the dementia manifestation).

4. Severity needs explicit documentation — cognitive assessment scores (MMSE, MoCA) and functional status descriptions support the severity level.

5. Dementia medications are strong diagnostic signals — donepezil, rivastigmine, galantamine, and memantine should always have a corresponding dementia diagnosis in the chart.

Look up any dementia code now — see the HCC tier, RAF coefficient, and V24/V28 comparison instantly.