Code systems

Code systems define the valid values for coded fields in Blue Button responses. When you see a coding object in a response, the system URI tells you which code system to look up.

What is a code system?

In FHIR, a code system is a defined set of codes with meanings. For example, the eob-type code system defines codes like CARRIER, INPATIENT, and PDE that identify claim types. When you see:

{
  "system": "https://bluebutton.cms.gov/fhir/CodeSystem/EOB-TYPE",
  "code": "CARRIER"
}

…you know this is a carrier (physician/supplier) claim.

How coding systems work

FHIR uses coding systems to represent standardized values. A coded value has three parts:

{
  "coding": [
    {
      "system": "https://bluebutton.cms.gov/resources/codesystem/eob-type",
      "code": "CARRIER",
      "display": "Carrier (professional) claim"
    }
  ]
}

• system A URI identifying which coding system the code belongs to
• code The coded value
• display Human-readable description

Blue Button uses coding systems from several sources:

For a complete listing: Blue Button Code System Listing (CSV).

Industry-standard code systems

The Blue Button API supplies codified data using several terminology and coding systems:

Using Code Systems with the Blue Button API

Find details about coding systems in the Blue Button Code System Listing (CSV).

The Blue Button API also provides data in FHIR Extensions. FHIR extensions are custom data elements not included in the FHIR standard. Check the data dictionary for further details.