{
  "resourceType": "Questionnaire",
  "status": "active",
  "item": [
    {
      "linkId": "cha",
      "text": "CHA₂DS₂-VASc Stroke Risk Score",
      "type": "group",
      "item": [
        {
          "linkId": "cha-chf",
          "text": "Congestive heart failure or left ventricular dysfunction",
          "type": "boolean"
        },
        {
          "linkId": "cha-htn",
          "text": "Hypertension",
          "type": "boolean"
        },
        {
          "linkId": "cha-age",
          "code": [
            {
              "system": "http://loinc.org",
              "code": "30525-0"
            }
          ],
          "text": "Age (years)",
          "type": "integer",
          "extension": [
            {
              "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-unit",
              "valueCoding": {
                "system": "http://unitsofmeasure.org",
                "code": "a",
                "display": "years"
              }
            }
          ]
        },
        {
          "linkId": "cha-diabetes",
          "text": "Diabetes mellitus",
          "type": "boolean"
        },
        {
          "linkId": "cha-stroke",
          "text": "Previous stroke, transient ischemic attack or thromboembolism",
          "type": "boolean"
        },
        {
          "linkId": "cha-vascular",
          "text": "Vascular disease (previous myocardial infarction, peripheral artery disease or aortic plaque)",
          "type": "boolean"
        },
        {
          "linkId": "cha-female",
          "text": "Female sex",
          "type": "boolean"
        },
        {
          "linkId": "cha-score",
          "text": "CHA₂DS₂-VASc score (0–9)",
          "type": "integer",
          "readOnly": true,
          "extension": [
            {
              "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-calculatedExpression",
              "valueExpression": {
                "language": "text/fhirpath",
                "expression": "iif(%resource.item.where(linkId='cha').item.where(linkId='cha-age').answer.valueInteger.exists(), (iif((%resource.item.where(linkId='cha').item.where(linkId='cha-chf').answer.valueBoolean), 1, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-htn').answer.valueBoolean), 1, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-age').answer.valueInteger >= 75), 2, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-diabetes').answer.valueBoolean), 1, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-stroke').answer.valueBoolean), 2, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-vascular').answer.valueBoolean), 1, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-age').answer.valueInteger >= 65 and %resource.item.where(linkId='cha').item.where(linkId='cha-age').answer.valueInteger < 75), 1, 0) + iif((%resource.item.where(linkId='cha').item.where(linkId='cha-female').answer.valueBoolean), 1, 0)), {})"
              }
            }
          ]
        }
      ]
    }
  ]
}