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Procedure Modifier

proc_mod_1
clinical
Updated 5/16/2026

Definition

A two-character HCPCS or CPT modifier code appended to a primary procedure code on a medical or professional claim to provide additional clinical or billing context, such as GP for physical therapy or 25 for a significant separate evaluation. Used in claims adjudication and reimbursement calculations.

Standard Abbreviation

proc_mod_1

Category

clinical

Database Usage

-- Example column naming
CREATE TABLE claims (
  clm_id VARCHAR(50),
  proc_mod_1 VARCHAR(100),  -- Procedure Modifier (max 100 chars)
  ...
);

-- Example in SELECT
SELECT
  clm_id,
  proc_mod_1 as procedure_modifier
FROM claims;

Example database column name

ISO-11179 snake_case standard

-- Recommended column name
proc_mod_1

-- Example DDL
CREATE TABLE healthcare_data (
  record_id   VARCHAR(50)   NOT NULL,
  proc_mod_1   VARCHAR(100),  -- Procedure Modifier (max 100 chars)
  created_dt  TIMESTAMP     NOT NULL DEFAULT NOW()
);

Column names follow the ISO-11179 naming convention: lowercase, underscore-separated, using the standard abbreviation as a prefix where applicable.

Why This Term Matters

Clinical terms are the building blocks of risk adjustment, quality measurement, and value-based care analytics. A data engineer who understands this terminology can design schemas that correctly capture patient conditions, procedures, and encounters — enabling accurate HCC scoring, HEDIS measure attribution, and CMS reporting. Misclassifying clinical fields in a data warehouse cascades into incorrect RAF scores and failed regulatory submissions.

Common uses in healthcare data

  • Risk stratification and population health analytics
  • CMS-HCC risk adjustment and RAF score calculation
  • Quality measure attribution and HEDIS reporting
  • Clinical data warehouse schema design
  • Value-based care contract performance tracking
  • Epic MyChart and Cerner PowerChart clinical data extraction for analytics pipelines
  • Snowflake VARIANT column mapping for semi-structured HL7 FHIR clinical payloads
  • Databricks Delta Lake pipeline orchestration for longitudinal patient cohort analysis

Related Healthcare Standards

HL7 FHIR R4

Defines clinical resource models (Patient, Condition, Observation, Encounter) that map directly to clinical data warehouse schemas and interoperability pipelines.

ICD-10-CM / ICD-10-PCS

The diagnosis and procedure coding systems mandated for all clinical documentation and claims in the US healthcare system.

HEDIS (NCQA)

Specifies clinical quality measure definitions that determine how clinical data is collected, attributed, and reported for Stars and value-based care contracts.

Data Quality Considerations

  • ICD-10-CM codes are frequently entered with invalid trailing characters or missing decimal points — validate against the current CMS ICD code reference table before loading into your clinical data warehouse.
  • Clinical date fields (admit date, discharge date, procedure date) often arrive with timezone offsets stripped — standardize to UTC at ingestion and store as TIMESTAMP_NTZ in Snowflake or TIMESTAMP in Databricks.
  • Null vs. unknown must be distinguished in clinical data: a missing diagnosis code may mean 'not documented' rather than 'not applicable' — use explicit sentinel values and document the distinction in your data dictionary.

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