HCPCS - Healthcare Common Procedure Coding System

The Healthcare Common Procedure Coding System (HCPCS, often pronounced by its acronym as "hick picks") is a set of health care codes based on the American Medical Association's Current Procedural Terminology (CPT). Wikipedia It is a collection of codes that represent procedures, supplies, products and services which may be provided to Medicare beneficiaries and to individuals enrolled in private health insurance programs.

Sources

To build the HCPCS vocabulary two sources are consumed: the UMLS master files and the Medicare coding data.

Transformation

The procedures for transforming Concepts from the source to the OMOP Standard Vocabularies can be found on the OHDSI GitHub.

Concept Names

All Concepts are assigned the longest of all available names.

Concept Code

The alphanumeric HCPCS code is used for the concept code, built from a character in position 1 followed by 4 digits in position 2 to 5.

Standard Concepts

All valid HCPCS concepts are Standard concepts unless they refer to 'HCPCS Class' concept class. However, if concepts are mapped to Standard concepts in the respective domains they are considered Non-standard.

Domains

In HCPCS domains are assigned manually according to the semantics and automatically according to the domain of a target Standard concept that the respective HCPCS concept is mapped over to.

Domain	Notes
Condition
Device
Drug
Measurement
Observation
Procedure
Visit
Provider

Concept Classes

HCPCS has two relevant Concept Classes: "HCPCS" and "HCPCS Modifier". "HCPCS" build the majority of the codes and represent the regular concepts as described before. "HCPCS Modifier" Concepts explain a certain main concept by adding a certain attribute such as "Administered intravenously" or "Administered subcutaneously". They do not follow the above described format for codes as they have an alphanumeric two character code. A third class is "HCPCS class", a classification system, for which the concepts have now been deprecated. It has a three character code format.

Class	Notes
HCPCS
HCPCS Modifier
HCPCS Class

Concept Relationships

There are mapping ('Maps to') and hierarchical ('Is a') relationships.

HCPCS mappings

Whether HCPCS concepts could be semantically mapped to Standard vocabularies, they are mapped over and deStandardized. As HCPCS represents a Procedure vocabulary, most of its concepts belong to the 'Procedure' and 'Observation' domains and are mapped over to SNOMED/OMOP Extension concepts. Concepts in the 'Drug', 'Measurement', 'Condition', 'Visit', 'Provider' domains are mapped over to the respective Standard vocabularies. All mappings are manually maintained by a team of curators.

Most mappings establish one-to-one equivalence between the Concepts. However, some HCPCS Concepts are pre-coordinated (consist of several semantic components), contain negations, declarations about conditions at an unspecified time in the past (e.g. medical history of), declarations about people other than the patient (e.g. family history), lab test findings, mixed mother/child conditions or Observations. All these cases are properly handled as described in the Mapping description.

HCPCS Drug mapping

Since most of HCPCS Drug codes are product-specific, we map them to the particular Branded Drugs in RxNorm. In case when one HCPCS code is assigned to several brands or several drug forms we use more general ancestor RxNorm concepts. Each HCPCS Drug concept name contains a billing unit, which essentially is a part of an administered dose. Since RxNorm concepts do not address doses that are administered to patients, but describe dosage forms of marketed pharmaceuticals, in most of cases doses in the source and the target concepts are not equal. See detailed information at the Find-A-Code website.

Hierarchy

Currently Standard HCPCS cocncepts are being embedded into SNOMED/OMOP Extension hierarchy. All hierarchical relationships are built manually. We don't create hierarchical relationships for non-Standard mapped concepts.

Instructions for ETL

All non-Standard HCPCS concepts have to be mapped to the corresponding Standard Concepts using the CONCEPT_RELATIONSHIP table ("Maps to" and occasionally "Maps to value" records).