>Welcome to MedictModelFHIR Basics

FHIR Basics

Fast Healthcare Interoperability Resources (FHIR) is the healthcare standard on which Medict is built. This guide covers the fundamental concepts you need to understand when working with Medict.

What is FHIR?

FHIR (pronounced "fire") is a standard for exchanging healthcare information electronically. It provides a common way to represent and share healthcare data across different systems.

Core FHIR Concepts

Resources

FHIR resources are the basic building blocks of healthcare data. Each resource represents a specific type of healthcare information.

Common Resources:

  • Patient - Information about a patient
  • Practitioner - Healthcare provider information
  • Encounter - A patient visit or interaction
  • Observation - Clinical measurements and findings
  • Diagnosis - Medical diagnoses
  • Medication - Medication information
  • Appointment - Scheduled appointments

Resource Structure

Every FHIR resource has:

  • id: Unique identifier
  • meta: Metadata about the resource
  • text: Human-readable summary
  • identifier: Additional identifiers
  • status: Current state of the resource
  • subject: What the resource is about

Example Patient Resource

{
  "resourceType": "Patient",
  "id": "example-patient",
  "identifier": [
    {
      "use": "usual",
      "type": {
        "coding": [
          {
            "system": "http://hl7.org/fhir/identifier-type",
            "code": "MR"
          }
        ]
      },
      "value": "12345"
    }
  ],
  "name": [
    {
      "use": "official",
      "family": "Smith",
      "given": ["John", "Michael"]
    }
  ],
  "gender": "male",
  "birthDate": "1990-01-15",
  "address": [
    {
      "use": "home",
      "line": ["123 Main St"],
      "city": "Anytown",
      "state": "CA",
      "postalCode": "12345",
      "country": "US"
    }
  ]
}

FHIR Data Types

Primitive Types

  • string - Text data
  • integer - Whole numbers
  • decimal - Decimal numbers
  • boolean - True/false values
  • date - Date only (YYYY-MM-DD)
  • dateTime - Date and time
  • time - Time only (HH:MM:SS)
  • uri - Uniform Resource Identifier
  • url - Web address

Complex Types

  • Coding - Coded values with system and code
  • CodeableConcept - Flexible coding with text
  • Reference - Reference to another resource
  • Identifier - Unique identifiers
  • HumanName - Person names
  • Address - Physical addresses
  • ContactPoint - Phone, email, etc.

Working with Resources in Medict

Creating Resources

import { MedictClient } from '@medplum/core';

const client = new MedictClient();

// Create a new patient
const patient = await client.createResource({
  resourceType: 'Patient',
  name: [{
    use: 'official',
    family: 'Doe',
    given: ['Jane']
  }],
  gender: 'female',
  birthDate: '1985-06-15'
});

Reading Resources

// Read a specific patient
const patient = await client.readResource('Patient', 'patient-id');

// Search for patients
const patients = await client.searchResources('Patient', {
  name: 'Smith',
  gender: 'male'
});

Updating Resources

// Update a patient
patient.name[0].given = ['John', 'Michael'];
const updatedPatient = await client.updateResource(patient);

Deleting Resources

// Delete a patient
await client.deleteResource('Patient', 'patient-id');

Search and Querying

Basic Search

// Search by name
const patients = await client.searchResources('Patient', {
  name: 'Smith'
});

// Search by multiple criteria
const encounters = await client.searchResources('Encounter', {
  patient: 'Patient/patient-id',
  status: 'finished',
  date: 'ge2023-01-01'
});

Advanced Search

// Complex search with modifiers
const observations = await client.searchResources('Observation', {
  'code': 'http://loinc.org|8480-6', // Blood pressure
  'patient': 'Patient/patient-id',
  'date': 'ge2023-01-01',
  'value-quantity': 'gt120' // Systolic > 120
});

References and Relationships

Internal References

{
  "resourceType": "Observation",
  "subject": {
    "reference": "Patient/patient-id"
  },
  "performer": [
    {
      "reference": "Practitioner/practitioner-id"
    }
  ]
}

External References

{
  "resourceType": "Observation",
  "subject": {
    "reference": "https://external-system.com/Patient/external-id",
    "display": "John Smith"
  }
}

Coding Systems

Common Coding Systems

  • LOINC - Laboratory and clinical observations
  • SNOMED CT - Clinical terminology
  • ICD-10 - Disease classification
  • CPT - Procedure codes
  • RxNorm - Medication terminology

Using Codes

{
  "resourceType": "Observation",
  "code": {
    "coding": [
      {
        "system": "http://loinc.org",
        "code": "8480-6",
        "display": "Systolic blood pressure"
      }
    ],
    "text": "Blood pressure"
  },
  "valueQuantity": {
    "value": 120,
    "unit": "mmHg",
    "system": "http://unitsofmeasure.org",
    "code": "mm[Hg]"
  }
}

Best Practices

1. Use Standard Codes

Always use standard coding systems when possible to ensure interoperability.

2. Include Human-Readable Text

Provide both coded values and human-readable text for better usability.

3. Validate Data

Use FHIR validation tools to ensure your resources are valid.

4. Handle Missing Data

Use appropriate FHIR patterns for missing or unknown data.

5. Version Resources

Use versioning to track changes to resources over time.

Next Steps