R40.2A
BillableNontraumatic coma due to underlying condition
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is R40.2A an HCC code?
Yes. R40.2A maps to Coma, Brain Compression/Anoxic Damage under the CMS-HCC V28 risk adjustment model (and Coma, Brain Compression/Anoxic Damage under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for R40.2A
For R40.2A to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed R40.2A during that encounter — not just copy-forwarded from a problem list.
What This Code Means
R40.2A is the ICD-10-CM diagnosis code for nontraumatic coma due to underlying condition. A state of complete unconsciousness caused by an underlying medical condition rather than head trauma. R40.2A sits in the ICD-10-CM chapter for symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (r00-r99), within the section covering symptoms and signs involving cognition, perception, emotional state and behavior (r40-r46).
Under the CMS-HCC V28 risk adjustment model, R40.2A maps to Coma, Brain Compression/Anoxic Damage (HCC 202) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, R40.2A mapped to the same category but with a base RAF weight of 0.546 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code when coma is due to conditions like hypoglycemia, stroke, infection, or metabolic disorders. Because R40.2A maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for R40.2A sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code when coma is due to conditions like hypoglycemia, stroke, infection, or metabolic disorders
- •Code the underlying condition as the primary diagnosis when possible; this code describes the manifestation
Clinical Significance
Nontraumatic coma due to underlying condition indicates profound unconsciousness caused by medical conditions rather than trauma, representing severe illness requiring intensive care management. This specific code provides better clinical precision than unspecified coma and helps identify the medical nature of the unconscious state.
Documentation Requirements
- ✓Documentation of coma state
- ✓Underlying medical condition identified
- ✓Non-traumatic etiology confirmed
- ✓Glasgow Coma Scale scores
- ✓Neurological assessment findings
- ✓Medical conditions causing the coma
- ✓Response to treatment of underlying condition
- ✓Duration and progression of coma
Excludes 1 — Do NOT code together
Code First
- underlying condition