What are FHIR Resources?

The complexity of healthcare data can be attributed in part to its vastness. FHIR attempts to address this by breaking down healthcare data into categories such as patients, hospital visits, lab results, claims information and representing each with a FHIR Resource. The 157 Resources are the fundamental building blocks of FHIR.

FHIR resources contain data elements, for example a Patient resource will contain elements such as patient name, date of birth and gender. They also include constraints, e.g. some elements are mandatory, and relationships between elements.

Each FHIR Resource on a server can be identified by a unique URL. E.g. https://fhir.server.com/fhir/Patient will locate Patient resources.

Principles of FHIR

FHIR Resources are governed by the following principles in order to enable interoperability:

• Reuse: Resources are designed to avoid redundancy, allowing reuse through customization via extensions and profiles.
• Performance: The simplicity of JSON resources allows quick exchange across networks
• Usability: They are designed to allow use by both technical and non-technical users alike
• Fidelity: Validation is an important part of FHIR, and as mentioned by Grahame in his appearance on our Digital Health Hackers podcast, has caused a cultural shift in health IT operations
• Implementability: FHIR meets its goal of being developer friendly, it can be easily understood as it uses common healthcare technologies

The 80-20 rule

Resources were built with the Pareto principle in mind, covering 80% of common use cases and letting individual implementations handle the remaining 20% of use cases.

Example FHIR Patient Resource

Here is a sample patient resource.

{
    "resourceType": "Patient",
    "name": [
        {
            "use": "official",
            "given": ["John"],
            "family": "Doe"
        }
    ],
    "gender": "female",
    "birthDate": "2000-05-08",
    "telecom": [
        {
            "system": "phone",
            "value": "9876543210",
            "use": "mobile"
        },
        {
            "system": "email",
            "value": "abc@example.com",
            "use": "home"
        }
    ],
    "address": [
        {
            "line": ["123, House and Street"],
            "city": "City",
            "state": "State",
            "postalCode": "98765",
            "country": "USA"
        }
    ]
}

Validating a FHIR Resource

Validating a FHIR resource is a necessary step towards ensuring consistency, accuracy, and hence, interoperability of data. In validating a FHIR resource, you check the structure of the resource against defined FHIR standards to identify errors and maintain integrity of data.

Two commonly used online FHIR validation tools are the official FHIR validator and the Inferno Resource validator.