> ## Documentation Index
> Fetch the complete documentation index at: https://developer.suki.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Diagnosis codes

> FAQ on diagnosis code types in Ambient API structured data, including ICD-10 and HCC

<AccordionGroup>
  <Accordion title="What is the difference between ICD-10 and HCC codes?">
    ICD-10 and HCC codes serve different purposes in clinical documentation:

    **ICD-10 (International Classification of Diseases, 10th Revision)**

    * A standardized system of codes used to classify and record diagnoses, symptoms, and procedures.
    * Used for billing, clinical documentation, and interoperability across healthcare systems.
    * Example: `I10` = Essential hypertension.
    * ICD-10 is the **primary identifier** Suki uses internally to match, deduplicate, and process diagnoses.

    **HCC (Hierarchical Condition Category)**

    * A risk-adjustment coding model used primarily in value-based care and Medicare Advantage programs.
    * HCC codes are derived from ICD-10 codes: CMS groups related ICD-10 codes into HCC categories to estimate a patient's expected healthcare costs.
    * Not every ICD-10 code maps to an HCC category: only those that significantly affect patient risk scores do.
    * Example: ICD-10 `I10` (Essential hypertension) maps to HCC 136.

    **How they relate in Suki structured data:**

    * Suki processes and stores diagnoses using ICD-10 as the source of truth.
    * In API structured data, HCC categories appear in the diagnosis `codes` array with `type: "HCC"`.
    * In the Web SDK, the `hccCode` field in the [Diagnosis type](/web-sdk/api-reference/types/diagnosis) surfaces the HCC category that corresponds to the ICD-10 code, when one exists.
    * You can use HCC output to support risk-adjustment workflows or value-based care reporting in your integration.

    |             | ICD-10                    | HCC                                  |
    | ----------- | ------------------------- | ------------------------------------ |
    | **Purpose** | Clinical diagnosis coding | Risk adjustment and cost prediction  |
    | **Scope**   | All diagnoses             | Subset of high-impact diagnoses      |
    | **Used by** | All payers, EHRs          | Medicare Advantage, value-based care |
    | **In Suki** | Primary identifier        | Supplemental output field            |

    See [Ambient Session Structured Data](/api-reference/ambient-content/structured-data) and [Supported Diagnosis Codes](/api-reference/info/diagnosis) for endpoint details.
  </Accordion>

  <Accordion title="Can I send HCC codes in session context?">
    No. HCC codes are returned in structured data output only. Send ICD10 or IMO codes in session context. Suki derives HCC categories from the ICD-10-CM code when you retrieve structured data.

    See [Ambient Session Structured Data](/api-reference/ambient-content/structured-data#diagnosis-codes-in-structured-data).
  </Accordion>
</AccordionGroup>