Substance abuse HCC refers to a set of diagnostic categories within the Hierarchical Condition Category system that the Centers for Medicare and Medicaid Services (CMS) uses to predict healthcare costs for patients with substance use disorders. When a provider documents a substance-related diagnosis and assigns the right code, it maps to a specific HCC that increases the patient’s risk score, which in turn affects the payments a health plan receives to cover that patient’s care.
If you’ve encountered this term, you’re likely working in medical coding, billing, or healthcare administration and need to understand how substance use diagnoses factor into risk adjustment. Here’s how the system works and what it means in practice.
How HCCs Work in Risk Adjustment
The HCC system groups thousands of individual diagnosis codes into a smaller number of clinically meaningful categories. CMS uses these categories to estimate how much a patient is likely to cost the healthcare system in a given year. Each HCC carries a numerical weight, and the sum of a patient’s HCC weights (along with demographic factors like age and sex) produces a Risk Adjustment Factor, or RAF score. Higher RAF scores mean higher predicted costs and larger payments from CMS to the insurer.
For substance use disorders, this matters because patients with active dependence, withdrawal complications, or substance-induced psychosis tend to need more intensive and expensive care. Capturing these diagnoses accurately ensures that health plans receive appropriate funding to cover that care.
Which Substance Use Diagnoses Map to an HCC
Not every substance-related diagnosis triggers an HCC. The distinction between “use,” “abuse,” and “dependence” matters significantly in coding, and the specific ICD-10 code a provider selects determines whether the diagnosis maps to an HCC at all.
Diagnoses that do map to an HCC include moderate and severe alcohol use disorder, opioid use disorder at any severity level, methamphetamine use disorder, polysubstance dependence, and substance-related intoxication or withdrawal with dependence. Conditions in sustained remission also count. For example, a patient with severe alcohol use disorder in sustained remission still maps to an HCC.
Diagnoses that typically do not map to an HCC include mild alcohol use disorder, a history of alcohol abuse without a current diagnosis, and opioid intoxication without an underlying dependence diagnosis. This is a common source of missed or incorrect coding: a provider documents “alcohol abuse” without specifying severity, and the resulting code (F10.10 for mild alcohol use disorder) falls outside HCC mapping.
The Specific HCC Categories for Substance Use
The HCC model has been updated over time, and the category numbers depend on which version is in use. Under the older CMS-HCC v24 model, substance use disorders fell into two main categories: HCC 54 (Drug/Alcohol Psychosis) and HCC 55 (Drug/Alcohol Dependence). These were broad groupings that combined drug and alcohol conditions together.
The newer v28 model, which CMS began phasing in for Medicare Advantage in 2024, splits substance use into five more specific categories:
- HCC 135: Drug use with psychotic complications
- HCC 136: Alcohol use with psychotic complications
- HCC 137: Drug use disorder, moderate or severe, or drug use with non-psychotic complications
- HCC 138: Drug use disorder, mild and uncomplicated (excluding cannabis)
- HCC 139: Alcohol use disorder, moderate or severe, or alcohol use with specified non-psychotic complications
The system is hierarchical, meaning if a patient qualifies for both a psychosis-related category and a dependence-only category, only the higher-weighted psychosis category counts. This prevents double-counting within the same disease group.
For Marketplace (ACA) plans, a separate HHS-HCC model applies. In that system, the relevant categories are HCC 81 (Drug Psychosis) and HCC 82 (Drug Dependence), which carry substantial risk weights. On a Silver plan, for instance, either of these categories adds roughly 3.4 to a patient’s risk score.
Documentation Requirements for Substance Use HCCs
A substance use diagnosis only counts toward risk adjustment if the medical record supports it with adequate documentation. CMS and health plans evaluate this using what’s known as MEAT criteria: the provider must show evidence of Monitoring, Evaluating, Assessing, or Treating the condition during the visit. A simple list of diagnoses on a problem list is not sufficient.
For a substance use disorder, this could look like reviewing a patient’s treatment progress, discussing relapse prevention, continuing a medication regimen, ordering relevant lab work, or documenting a referral to a specialist or treatment program. The key is that the provider actively addressed the condition during the encounter, not just acknowledged it exists.
One commonly overlooked detail: conditions in remission still need to be documented and coded each year. A patient with alcohol use disorder in sustained remission qualifies for an HCC, but only if the provider documents and addresses the condition during a face-to-face visit in the current reporting period. If it goes undocumented for a year, it drops off the patient’s risk profile.
Common Reasons Substance Use HCCs Get Rejected
During Risk Adjustment Data Validation (RADV) audits, CMS reviews whether the HCCs a health plan submitted are actually supported by medical records. Expert coders compare the submitted diagnosis codes against the documentation, and any unsupported HCC is removed from the patient’s RAF score, reducing the plan’s payment.
The most frequent problems with substance use HCCs include coding a “rule-out” or “possible” substance use disorder as a confirmed diagnosis in an outpatient setting (which violates coding guidelines), reporting a historical condition as current when there’s no documentation of active management, and selecting a nonspecific code when the record supports a more precise one. For example, coding “unspecified drug use” when the provider clearly documented opioid dependence results in a less accurate code that may not map to the correct HCC.
Another common issue is capturing only the primary reason for a visit and ignoring coexisting substance use disorders. If a patient comes in for diabetes management but also has documented opioid use disorder that the provider addresses during the same visit, both conditions should be coded. Reporting only the primary diagnosis leaves legitimate HCCs uncaptured.
Why This Matters Beyond Billing
Risk adjustment isn’t just an accounting exercise. When substance use disorders go undocumented or undercoded, the health plan receives less funding than it needs to cover those patients’ care. Over time, this creates a financial disincentive for plans to invest in behavioral health services or enroll patients with complex substance use needs. Research has shown that plans may have incentives to limit mental health and substance use coverage when risk adjustment doesn’t adequately capture these conditions.
Accurate coding also gives a clearer picture of population health. Public health agencies and researchers rely on coded data to understand the prevalence of substance use disorders and allocate resources. When these conditions are systematically undercoded, the data understates the scope of the problem, and funding decisions suffer as a result.