Activity Definition

Summary

In CARE, ActivityDefinition is used to define reusable templates for clinical actions, such as lab tests or medication requests. Each definition standardizes how a particular diagnostic activity should be instantiated at runtime — enabling consistent behavior across service requests and automated billing.

Core Relationships

Related Resource	Purpose
ServiceRequest	Primary output when ActivityDefinition is applied
ChargeItemDefinition	Linked to define billing behavior
SpecimenDefinition	Defines required specimens for lab tests
ObservationDefinition	Specifies expected observation outcomes

Supported Fields

Field Name	Description	Example
id	Internal identifier	AD-001
version	Versioning control for updates	1
slug	Unique name within a facility	cbc-test
derived_from_url	Source or canonical reference	https://fhir.care/ad/cbc
title	Human-readable name	Complete Blood Count
subtitle	Optional secondary title	CBC (Routine)
status	Draft, active, retired	active
category	Clinical category (from FHIR extensible valueset)	laboratory
description	Long-form description	"Standard CBC test"
purpose	Rationale for defining the activity	"Baseline health evaluation"
usage	Description of clinical usage	"Used for anemia screening"
facility	Facility where the definition is used	Facility/Medicity
kind	Type of FHIR resource created by this template (e.g., ServiceRequest)	ServiceRequest
code	Clinical code (e.g., SNOMED or internal code for the action)	718-7
body_site	Applicable body site, if relevant	left arm
locations[]	List of locations where this test can be performed	[LabA, LabB]
specimenRequirement[]	Linked SpecimenDefinition entries required for the test	Specimen/Blood
observationResultRequirement[]	Linked ObservationDefinition entries that define expected result structure	[Hemoglobin, WBC, RBC]

Functional Workflow

• Define Activity

  Admin defines a test (e.g., CBC) using ActivityDefinition, linking to specimens, observations, and charge items.

• Apply ActivityDefinition

  When a ServiceRequest is created (via UI/API), the system references the relevant ActivityDefinition and uses it to instantiate the required resource.

• Auto-Generate ChargeItems

  If charges are linked to the ActivityDefinition, they are also instantiated.

Schema Definition?

{
  "id" : "<str>", // Internal Identifier
  "version" : "<int>", // Version of the Activity Definition
  "slug" : "<string>", // Unique name per facility
  "derived_from_url" : "<url>", // URL this object was derived from
  "title" : "<string>", // Name for this activity definition (human friendly)
  "subtitle" : "<string>", // Subordinate title of the activity definition
  "status" : "<string>", // R!  draft | active | retired | unknown
  "category" : "<code>" // Bound to https://build.fhir.org/valueset-servicerequest-category.html Extensible
  // "contact" : [{ ContactDetail }], // Contact details for the publisher
  "description" : "<markdown>", // Natural language description of the activity definition
  "purpose" : "<markdown>", // Why this activity definition is defined
  "usage" : "<markdown>", // Describes the clinical usage of the activity definition
  "facility" : "<id|fk>", // Facility where this Account is created
  // topic" : "", // No Valid use for this right now
  "kind" : "<string>", // FHIR Resource Type that is created by this Definition, Options will be internally identified by the system
  "code" : "<code>", // Bound to Snomed, controls what kind of Def this is, Example Procedure Codes
  //"intent" : "<code>", // proposal | plan | directive | order | original-order | reflex-order | filler-order | instance-order | option
  //"priority" : "<code>", // routine | urgent | asap | stat
  "body_site" : "<code>" // Bound to the Body site Valueset
  "locations" : ["<id|fk>"], // Foreign key to location
  "specimenRequirement" : ["<id|fk>"], // Points to SpecimentDefinition
  //"observationRequirement" : ["<id|fk>"], //Points to Observation Requirement
  "observationResultRequirement" : ["<id|fk>"], // What observations must be produced by this action
}