F18.159
BillableInhalant abuse with inhalant-induced psychotic disorder, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is F18.159 an HCC code?
Yes. F18.159 maps to Drug/Alcohol Psychosis under the CMS-HCC V28 risk adjustment model (and Drug/Alcohol Psychosis 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 F18.159
For F18.159 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 F18.159 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
F18.159 is the ICD-10-CM diagnosis code for inhalant abuse with inhalant-induced psychotic disorder, unspecified. A person is abusing inhalants and is experiencing psychosis caused by the inhalant use, but the specific type (delusions or hallucinations) is not specified. F18.159 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering mental and behavioral disorders due to psychoactive substance use (f10-f19).
Under the CMS-HCC V28 risk adjustment model, F18.159 maps to Drug/Alcohol Psychosis (HCC 135) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, F18.159 mapped to the same category but with a base RAF weight of 0.434 — 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 only when psychotic symptoms are documented but the specific manifestation cannot be determined. Because F18.159 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 F18.159 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when psychotic symptoms are documented but the specific manifestation cannot be determined
- •Query the provider for clarification on whether delusions, hallucinations, or other psychotic features are present
Clinical Significance
Inhalant abuse with unspecified psychotic disorder captures psychosis from inhalant use when the documentation does not clarify whether delusions or hallucinations are the primary feature. Despite being unspecified, this still maps to the higher-value psychosis HCC, making it clinically and financially important to capture.
Documentation Requirements
- ✓Documentation of inhalant abuse with psychotic symptoms
- ✓Evidence of psychosis linked to inhalant use
- ✓Provider query for specific psychotic features
- ✓Mental status examination supporting psychosis diagnosis
- ✓Treatment plan for psychotic symptoms
Commonly Confused Codes
- •F18.150 — With delusions; preferred when delusions are documented
- •F18.151 — With hallucinations; preferred when hallucinations are documented
- •F18.19 — With unspecified induced disorder; does NOT capture psychosis specifically and maps to lower HCC
- •F18.259 — Inhalant dependence with psychotic disorder, unspecified; use when dependence documented