V28 HCC 398
Major Head Injury with Loss of Consciousness < 1 Hour or Unspecified
Under the CMS-HCC V28 risk adjustment model (PY2026 Medicare Advantage), HCC 398 has a source-labeled community non-dual aged reference coefficient of 0.199, and 57 ICD-10-CM diagnosis codes appear in its official mapping. In the V28 hierarchy it is superseded by HCC 397 when a more severe category in the same disease group is also present.
RAF factors
The community factor varies by Medicaid and originally-disabled status; the institutional factor applies to long-term-institutional members. These are the CMS-HCC V28 PY2026 relative factors.
These are source-labeled code-level HCC coefficient references, not a full member score. Use the RAF Calculator with complete member context for CMS-HCC V28 PY2026. No score is shown unless every required source and calculation check passes.
V28 hierarchy
Trumped by: HCC 397 (a more severe category in the same disease group supersedes this one).
Supersedes: HCC 202, HCC 399 (this category is counted instead of these when they co-occur).
ICD-10-CM codes that map to HCC 398 (57)
ICD-10-CM codes in the official mapping for this category under CMS-HCC V28 PY2026. Open any code for its full description and coding guidance.
- S06.1X1ATraumatic cerebral edema with loss of consciousness of 30 minutes or less, initial encounter
- S06.1X2ATraumatic cerebral edema with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.1X9ATraumatic cerebral edema with loss of consciousness of unspecified duration, initial encounter
- S06.2X1ADiffuse traumatic brain injury with loss of consciousness of 30 minutes or less, initial encounter
- S06.2X2ADiffuse traumatic brain injury with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.2X9ADiffuse traumatic brain injury with loss of consciousness of unspecified duration, initial encounter
- S06.301AUnspecified focal traumatic brain injury with loss of consciousness of 30 minutes or less, initial encounter
- S06.302AUnspecified focal traumatic brain injury with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.309AUnspecified focal traumatic brain injury with loss of consciousness of unspecified duration, initial encounter
- S06.311AContusion and laceration of right cerebrum with loss of consciousness of 30 minutes or less, initial encounter
- S06.312AContusion and laceration of right cerebrum with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.319AContusion and laceration of right cerebrum with loss of consciousness of unspecified duration, initial encounter
- S06.321AContusion and laceration of left cerebrum with loss of consciousness of 30 minutes or less, initial encounter
- S06.322AContusion and laceration of left cerebrum with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.329AContusion and laceration of left cerebrum with loss of consciousness of unspecified duration, initial encounter
- S06.331AContusion and laceration of cerebrum, unspecified, with loss of consciousness of 30 minutes or less, initial encounter
- S06.332AContusion and laceration of cerebrum, unspecified, with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.339AContusion and laceration of cerebrum, unspecified, with loss of consciousness of unspecified duration, initial encounter
- S06.341ATraumatic hemorrhage of right cerebrum with loss of consciousness of 30 minutes or less, initial encounter
- S06.342ATraumatic hemorrhage of right cerebrum with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.349ATraumatic hemorrhage of right cerebrum with loss of consciousness of unspecified duration, initial encounter
- S06.351ATraumatic hemorrhage of left cerebrum with loss of consciousness of 30 minutes or less, initial encounter
- S06.352ATraumatic hemorrhage of left cerebrum with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.359ATraumatic hemorrhage of left cerebrum with loss of consciousness of unspecified duration, initial encounter
- S06.361ATraumatic hemorrhage of cerebrum, unspecified, with loss of consciousness of 30 minutes or less, initial encounter
- S06.362ATraumatic hemorrhage of cerebrum, unspecified, with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.369ATraumatic hemorrhage of cerebrum, unspecified, with loss of consciousness of unspecified duration, initial encounter
- S06.371AContusion, laceration, and hemorrhage of cerebellum with loss of consciousness of 30 minutes or less, initial encounter
- S06.372AContusion, laceration, and hemorrhage of cerebellum with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.379AContusion, laceration, and hemorrhage of cerebellum with loss of consciousness of unspecified duration, initial encounter
- S06.381AContusion, laceration, and hemorrhage of brainstem with loss of consciousness of 30 minutes or less, initial encounter
- S06.382AContusion, laceration, and hemorrhage of brainstem with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.389AContusion, laceration, and hemorrhage of brainstem with loss of consciousness of unspecified duration, initial encounter
- S06.4X1AEpidural hemorrhage with loss of consciousness of 30 minutes or less, initial encounter
- S06.4X2AEpidural hemorrhage with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.4X9AEpidural hemorrhage with loss of consciousness of unspecified duration, initial encounter
- S06.5X1ATraumatic subdural hemorrhage with loss of consciousness of 30 minutes or less, initial encounter
- S06.5X2ATraumatic subdural hemorrhage with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.5X9ATraumatic subdural hemorrhage with loss of consciousness of unspecified duration, initial encounter
- S06.6X1ATraumatic subarachnoid hemorrhage with loss of consciousness of 30 minutes or less, initial encounter
- S06.6X2ATraumatic subarachnoid hemorrhage with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.6X9ATraumatic subarachnoid hemorrhage with loss of consciousness of unspecified duration, initial encounter
- S06.811AInjury of right internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 30 minutes or less, initial encounter
- S06.812AInjury of right internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.819AInjury of right internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of unspecified duration, initial encounter
- S06.821AInjury of left internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 30 minutes or less, initial encounter
- S06.822AInjury of left internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.829AInjury of left internal carotid artery, intracranial portion, not elsewhere classified with loss of consciousness of unspecified duration, initial encounter
- S06.891AOther specified intracranial injury with loss of consciousness of 30 minutes or less, initial encounter
- S06.892AOther specified intracranial injury with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.899AOther specified intracranial injury with loss of consciousness of unspecified duration, initial encounter
- S06.8A1APrimary blast injury of brain, not elsewhere classified with loss of consciousness of 30 minutes or less, initial encounter
- S06.8A2APrimary blast injury of brain, not elsewhere classified with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.8A9APrimary blast injury of brain, not elsewhere classified with loss of consciousness of unspecified duration, initial encounter
- S06.9X1AUnspecified intracranial injury with loss of consciousness of 30 minutes or less, initial encounter
- S06.9X2AUnspecified intracranial injury with loss of consciousness of 31 minutes to 59 minutes, initial encounter
- S06.9X9AUnspecified intracranial injury with loss of consciousness of unspecified duration, initial encounter
Coder workflow notes
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Frequently asked questions
What is CMS-HCC V28 category 398?
HCC 398 is "Major Head Injury with Loss of Consciousness < 1 Hour or Unspecified", a Hierarchical Condition Category in the CMS-HCC V28 risk adjustment model (100% phase-in for payment year 2026). 57 ICD-10-CM codes appear in its official mapping.
What reference coefficient is published for HCC 398?
The source-labeled community non-dual aged reference coefficient for CMS-HCC V28 category 398 is 0.199. The exact coefficient varies by enrollment segment (community Medicaid and originally-disabled status, and institutional); the full segment table is published in the CMS V28 model files.
How many ICD-10-CM codes map to HCC 398?
57 ICD-10-CM diagnosis codes appear in the official mapping for CMS-HCC V28 category 398 (Major Head Injury with Loss of Consciousness < 1 Hour or Unspecified) for payment year 2026.
Which categories trump HCC 398 in the V28 hierarchy?
HCC 398 is superseded by HCC 397 (Major Head Injury with Loss of Consciousness > 1 Hour). When a more severe category in the same disease group is documented, it is counted instead of HCC 398.
Related references
Sources
CMS ICD-10-CM order-file billability plus the published mapping and CMS-HCC V28 PY2026 model software. CMS-HCC V28 model published at CMS.gov Risk Adjustors; ICD-10-CM member codes from the CMS ICD-10-CM code set.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed May 30, 2026.