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Medicare Advantage, Part D, Medicaid

ICD-10 to HCC crosswalk (reference)

medicare_silver.dim_icd10_hcc_crosswalk·live·silver·annual·CMS-HCC Risk Adjustment Model
Rows
171,676
Columns
10
History
2024 to 2027 (provisional — 2027 mappings are byte-identical to 2026; see gotchas)
Card
yesgrain, traps, filters
Typed tools
0

Superseded by medicare_silver.dim_icd10_hcc_crosswalk_v3 (every CMS mapping edition 2016-2027, restated 2026-10-07, #3237), read through medicare_semantic.vw_icd10_hcc_crosswalk_current_v1. This table matched only 2024-era header spellings, so it is missing CMS-HCC V23 (2019), CMS-HCC V24 (2020-2025), the 2021 V21 column, all RxHCC V05 and 5,384 multi-HCC rows; its 'V21' / 'V24' are the ESRD models and its RxHCC categories are spelled HCC<n>. Kept frozen as the rollback..

What it is

  1. 1A CMS reference crosswalk that maps each IC-10-CM diagnosis code to its Hierarchical Condition Category (HCC) under a specific CMS risk-adjustment model version and payment year.
  2. 2It is the lookup that turns a patient diagnosis into the HCC that drives Medicare Advantage / Part D risk scores and capitated payment — the diagnosis-to-risk-bucket dictionary behind MA and ACA risk-adjusted reimbursement.

Grain

KeyGrain
icd_codemodel_versionrate_year
  1. 1One row per (icd_code, model_version, rate_year) — i.e. one diagnosis code's HCC assignment under one risk model in one payment year.
  2. 2Verified unique: COUNT(DISTINCT (icd_code, model_version, rate_year)) = 171,676 = total row_count.
  3. 3Each such triple maps to exactly ONE hcc_category (0 triples have >1 HCC), so hcc_category is the looked-up VALUE, not part of the key.

How to read it

  1. 1To risk-adjust a 2026 MA Part C population, map each patient diagnosis to its current payment HCC: SELECT icd_code, hcc_category, icd_description FROM medicare_silver.dim_icd10_hcc_crosswalk WHERE model_version='V28' AND rate_year=2026 AND icd_code IN (...patient ICDs...).
  2. 2This returns the V28 HCC bucket per diagnosis, which then joins to the HCC coefficient/RAF tables to compute the risk score (use RxHCC_V08 instead for the Part D drug component).

Traps

  1. 1model_version is part of the grain and CHANGES the answer: the same ICD maps to different HCCs across models. Example 2026, ICD A0104 -> HCC39 under V21/V22/V24 but HCC92 under V28. NEVER look up an ICD without pinning model_version (use V28 for current MA Part C payment) AND rate_year.
  2. 2hcc_category is ALWAYS prefixed 'HCC' even for the Part D drug model RxHCC_V08 — the prefix does NOT distinguish payment-HCC from Rx-HCC. The two taxonomies use entirely different numbering (e.g. ICD A072 -> HCC6 under V28 but HCC5 under RxHCC_V08). The taxonomy is defined solely by model_version, not by the hcc_category string.
  3. 3rate_year 2027 is provisional: its 171k-subset is byte-identical to 2026 (0 mapping mismatches, same sha256_content_hash, source_url is '2027-initial'). Treat 2027 as a placeholder reuse of 2026 midyear-final mappings, not a confirmed independent CMS release; 2026 is the latest real/final year.
  4. 4Several columns look like keys but are NOT: hcc_category is the looked-up value (1 per grain triple, not a key); bronze_publication_id is strictly 1:1 with rate_year (redundant); icd_code alone is NOT unique (11,395 codes -> 171,676 rows). The only verified minimal key is (icd_code, model_version, rate_year).
  5. 5No is_current / snapshot / SCD column exists. The table is simply partitioned by rate_year (identity), each year = one CMS publication. There is no per-row versioning to dedup; asserted_at and parser_artifact_hash are provenance only (asserted_at = a ~6-min load on 2026-05-18, NOT the CMS publish date).
  6. 6icd_description is not a reliable dictionary: it can differ across years for the same code (CMS wording edits) and is duplicated per (model_version) row, so SELECT DISTINCT icd_description can return >1 string for one code. icd_code is dot-free (A0103) — strip dots before joining to a dotted ICD source.

Columns (10)

ColumnTypeMeaning
rate_yearintCMS payment/benefit year the mapping applies to (int). Partition column (identity partition). 4 values: 2024, 2025, 2026, 2027. Part of the grain key. Each year = one CMS publication load.
model_versionstringCMS risk-adjustment model that defines the HCC taxonomy. 5 values: V21, V22, V24, V28 (CMS-HCC payment models for MA Part C — V28 is the current/newest payment model, V21/V22/V24 are legacy/blend models still used in transition) and RxHCC_V08 (the Part D prescription-drug RxHCC model, a DIFFERENT taxonomy). Part of the grain key — the SAME ICD maps to DIFFERENT HCCs under different model_versions, so you must always filter this.
icd_codestringICD-10-CM diagnosis code in CMS dot-free format (e.g. 'A0103', not 'A01.03'). Lengths 3-7, no decimal points, no nulls. 11,395 distinct codes total. Part of the grain key.
hcc_categorystringThe Hierarchical Condition Category the diagnosis maps to, e.g. 'HCC92'. This is the LOOKED-UP VALUE, not a key. ALWAYS prefixed 'HCC' even for the RxHCC model, so the prefix does NOT tell you which taxonomy — the numbering only makes sense within a given model_version (numeric part ranges 1-463). 218 distinct values across all models; e.g. for 2026: V28 spans 115 HCCs, RxHCC_V08 84.
icd_descriptionstringPlain-English long description of the ICD-10 code (e.g. 'Typhoid pneumonia'). Sourced from the CMS mapping file. NOT a stable per-code dictionary — wording can drift across rate_year for the same code (15 codes differ, e.g. 'Megaloencephalic'->'Megalencephalic'), because it follows the year's published file. No nulls.
source_urlstringCMS download URL of the ZIP the mappings were parsed from (e.g. '.../2026-midyear-final-icd-10-mappings.zip'). One distinct URL per rate_year. Note the 2026 file is labeled 'midyear-final' while 2024/2025/2027 are 'initial' — provenance, not a join key.
sha256_content_hashstringSHA-256 of the source file content, for provenance/integrity. One distinct hash per rate_year — EXCEPT 2026 and 2027 share the identical hash (2027 reuses the 2026 midyear-final content). A change in this hash signals CMS republished the file.
bronze_publication_idstringProvenance ID of the bronze ingestion that produced this year's rows (e.g. 'hcc_all_2026_66d75bf7'). Exactly 1:1 with rate_year (4 ids, 4 years) — REDUNDANT with rate_year for grain; do not mistake it for a finer key.
asserted_attimestampTimestamp the silver rows were materialized/asserted. Only 4 distinct values, all within a ~6-minute window on 2026-05-18 — one assertion per rate_year load. This is a pipeline-load time, NOT when CMS published; use source_url/rate_year for CMS recency.
parser_artifact_hashstringHash identifying the parser code version that produced the rows. IDENTICAL across every row ('e10d366596d1c801') — a single parser version built the whole table; useful only to detect future reparses.

Query it

describe_data_source(source_fqn="medicare_silver.dim_icd10_hcc_crosswalk")     # the card, live
query_substrate(sql="SELECT * FROM medicare_silver.dim_icd10_hcc_crosswalk WHERE icd_code = '<value>' AND model_version = '<value>' AND rate_year = '<value>' LIMIT 100")
ItemValue
Typed tools that read itnone; raw SQL
Identity keyrate_year,model_version,icd_code,hcc_category
Joinhow_to_join(source_fqn="medicare_silver.dim_icd10_hcc_crosswalk")
Raw doorAthena (read-only via query_substrate): medicare_silver.dim_icd10_hcc_crosswalk

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