Example of an EventDefinition using the data event approach.

{
  "resourceType" : "EventDefinition",
  "id" : "example-data",
  "extension" : [{
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
    "valueCode" : "informative"
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm",
    "valueInteger" : 6
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
    "valueCode" : "cds"
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/cqf-library",
    "valueCanonical" : "http://hl7.org/fhir/EventDefinition/ExampleEventDefinitionLogic"
  }],
  "url" : "http://hl7.org/fhir/EventDefinition/example-data",
  "name" : "DataEventDefinitionExample",
  "title" : "Data EventDefinition Example",
  "status" : "draft",
  "experimental" : true,
  "publisher" : "HL7 International / Clinical Decision Support",
  "contact" : [{
    "telecom" : [{
      "system" : "url",
      "value" : "http://www.hl7.org/Special/committees/dss"
    }]
  }],
  "description" : "Example of an EventDefinition using the data event approach.",
  "purpose" : "Monitor when 3 consecutive negative stick tests have occurred using a data change event.",
  "trigger" : [{
    "type" : "data-changed",
    "data" : [{
      "type" : "Observation",
      "codeFilter" : [{
        "path" : "code",
        "valueSet" : "http://example.org/ValueSet/stick-test-codes"
      }]
    }],
    "condition" : {
      "language" : "text/cql-expression",
      "expression" : "StickTest.consecutivelyAfter(%context).take(3).negative().count() = 3"
    }
  }]
}