FHIR Overview

The FHIR data model is developed by HL7 to enable electronic sharing of data for healthcare data exchange. Nerve builds additional abstractions on top of the FHIR data model to create a simpler developer experience and to provide a consistent interface across EHRs.

Resource Categories

Resources are the building blocks of the FHIR data model. The following table organizes the five main categories and their sub-components:

Category	Description	Components
Foundation Resources	Core infrastructure and directory resources for system support	• Security • Conformance • Terminology • Documents • Other
Base Resources	Common business resources across healthcare domains	• Individuals • Entities • Workflow • Management
Clinical Resources	Clinical concepts and healthcare delivery processes	• Clinical • Diagnostic • Medications • Care Provision • Request & Response
Financial Resources	Billing, claims, and payment processes	• Support • Billing • Payment • General
Specialized Resources	Specific use cases beyond routine clinical care	• Public Health & Research • Definitional Artifacts • Evidence-based Medicine • Quality Reporting • Medication Definition

See a list of all the resources here.

Key Components of FHIR Resources

Each FHIR resource contains several key components that define its structure and content:

Resource Metadata

Includes key details like resource ID, version ID, and last updated date to facilitate resource identification and management.

Narrative

Provides an HTML representation of a resource's content, enabling a human-readable view even if coded data isn't processable.

Extensions

Allow customization of resources for specific use cases beyond the core FHIR standard, using key-value pairs to represent additional data.

Structured Data

Represents the core 80% of use cases, including attributes like medical record number, name, gender, and birthdate in a patient resource.

Example FHIR Resources

{
  "resourceType": "Patient",
  // Resource Metadata
  "id": "example-patient",
  "meta": {
    "versionId": "1",
    "lastUpdated": "2024-03-15T10:30:00Z"
  },
 
  // Narrative (Human-readable representation)
  "text": {
    "status": "generated",
    "div": "<div xmlns=\"http://www.w3.org/1999/xhtml\">John Smith, Male, Born 1974-12-25</div>"
  },
 
  // Extensions (Custom data beyond base FHIR spec)
  "extension": [
    {
      "url": "http://example.org/fhir/StructureDefinition/preferred-language",
      "valueCode": "en-US"
    }
  ],
 
  // Structured Data (Core FHIR elements)
  "identifier": [
    {
      "use": "official",
      "type": {
        "coding": [
          {
            "system": "http://terminology.hl7.org/CodeSystem/v2-0203",
            "code": "MR"
          }
        ]
      },
      "system": "http://hospital.example.org",
      "value": "12345"
    }
  ],
  "active": true,
  "name": [
    {
      "use": "official",
      "family": "Smith",
      "given": ["John"]
    }
  ],
  "telecom": [
    {
      "system": "phone",
      "value": "+1-555-555-5555",
      "use": "home"
    },
    {
      "system": "email",
      "value": "john.smith@example.com"
    }
  ],
  "gender": "male",
  "birthDate": "1974-12-25",
  "deceasedBoolean": false,
  "address": [
    {
      "use": "home",
      "line": ["123 Main St"],
      "city": "Anytown",
      "state": "CA",
      "postalCode": "12345",
      "country": "USA"
    }
  ],
  "maritalStatus": {
    "coding": [
      {
        "system": "http://terminology.hl7.org/CodeSystem/v3-MaritalStatus",
        "code": "M",
        "display": "Married"
      }
    ]
  },
  "communication": [
    {
      "language": {
        "coding": [
          {
            "system": "urn:ietf:bcp:47",
            "code": "en-US",
            "display": "English (United States)"
          }
        ]
      },
      "preferred": true
    }
  ],
  "generalPractitioner": [
    {
      "reference": "Practitioner/f47ac10b-58cc-4372-a567-0e02b2c3d479",
      "id": "f47ac10b-58cc-4372-a567-0e02b2c3d479"
    }
  ],
  "managingOrganization": {
    "reference": "Organization/7d793037-3018-4b36-b892-4871744f1912",
    "id": "7d793037-3018-4b36-b892-4871744f1912"
  }
}

Resource References

FHIR resources frequently reference other resources using reference IDs. For example, a Patient resource might reference their primary care provider like this:

{
  "generalPractitioner": [{
    "reference": "Practitioner/f47ac10b-58cc-4372-a567-0e02b2c3d479",
    "id": "f47ac10b-58cc-4372-a567-0e02b2c3d479"
  }]
}

This means additional API calls are typically needed to "dereference" these IDs and retrieve the full referenced resources. However, Nerve automatically dereferences these references by default, providing the complete referenced resource data inline:

{
  "generalPractitioner": [{
    "reference": "Practitioner/f47ac10b-58cc-4372-a567-0e02b2c3d479",
    "id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
    "resource": {
      "resourceType": "Practitioner",
      "id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
      "name": [{
        "family": "Wilson",
        "given": ["Jane"],
        "prefix": ["Dr."]
      }],
      "qualification": [
        // ... additional practitioner details
      ]
    }
  }]
}

This auto-dereferencing saves developers time and reduces the number of API calls needed, while still maintaining compatibility with the FHIR standard.

FHIR Overview

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