Equal-To Operator on ValueQuantity in Observations

[vmontagh]

Description

The equal-to operator silently fails when used with ValueQuantity. When comparing an Observation's value with an integer, the result is always false, regardless of the value on the other side of the comparison (see the NoResult statement).

Attempting to access inner values, such as value.value, results in a type checker error. However, accessing unit.value works as expected. To resolve this issue, we resorted to type casting, as demonstrated in QuantityValueFromObservation below.

Input

library HeartRateValidation version '1.0'

include FHIRHelpers version '4.0.1' called FHIRHelpers

define function QuantityValueFromObservation(o FHIR.Observation):
  ( cast o.value as FHIR.Quantity ).value.value

define "WithHelper":
  [Observation] obs
    where QuantityValueFromObservation(obs) = 1


define "NoResult":
  [Observation] obs
    where obs.value = 1

// internal error - handleProtoValue expected runtimeResultType to be a Named type, got: Choice<Named<FHIR.decimal>, System.String, System.Boolean, System.Integer, System.Time, System.DateTime>
define "TypeCheckerIssue":
  [Observation] obs
    where obs.value.value = 1

// internal error - handleProtoValue expected runtimeResultType to be a Named type, got: Choice<Named<FHIR.decimal>, System.String, System.Boolean, System.Integer, System.Time, System.DateTime>
define "TypeCheckerIssue":
  [Observation] obs
    where obs.value.value.value = 1

Bundle

{
    "resourceType": "Bundle",
    "id": "example-bundle",
    "type": "collection",
    "entry": [
      {
        "fullUrl": "urn:uuid:heart-rate",
        "resource": {
          "resourceType": "Observation",
          "id": "heart-rate",
          "text": {
            "status": "generated"
          },
          "status": "final",
          "category": [
            {
              "coding": [
                {
                  "system": "http://terminology.hl7.org/CodeSystem/observation-category",
                  "code": "vital-signs",
                  "display": "Vital Signs"
                }
              ],
              "text": "Vital Signs"
            }
          ],
          "code": {
            "coding": [
              {
                "system": "http://loinc.org",
                "code": "8867-4",
                "display": "Heart Rate"
              }
            ],
            "text": "heart_rate"
          },
          "subject": {
            "reference": "Patient/example",
            "display": "Amy Shaw"
          },
          "encounter": {
            "display": "GP Visit"
          },
          "effectiveDateTime": "1999-07-02",
          "valueQuantity": {
            "value": 1,
            "unit": "beats/min",
            "system": "http://unitsofmeasure.org",
            "code": "/min"
          }
        }
      }
    ]
  }

output

{
  "bundleSource": "data/bundles/observations_heart_rate.json",
  "evalResults": [
    {
      "libName": "HeartRateValidation",
      "libVersion": "1.0",
      "expressionDefinitions": {
        "Heart Rate Vital Signs": {
          "@type": "System.ValueSet",
          "id": "http://fhir.verily.com/ValueSet/heath-rate"
        },
        "NoResult": [],
        "TypeCheckerIssue": [],
        "WithHelper": [
          {
            "@type": "FHIR.Observation",
            "value": {
              "id": {
                "value": "heart-rate"
              },
              "text": {
                "status": {
                  "value": "GENERATED"
                }
              },
              "status": {
                "value": "FINAL"
              },
              "category": [
                {
                  "coding": [
                    {
                      "system": {
                        "value": "http://terminology.hl7.org/CodeSystem/observation-category"
                      },
                      "code": {
                        "value": "vital-signs"
                      },
                      "display": {
                        "value": "Vital Signs"
                      }
                    }
                  ],
                  "text": {
                    "value": "Vital Signs"
                  }
                }
              ],
              "code": {
                "coding": [
                  {
                    "system": {
                      "value": "http://loinc.org"
                    },
                    "code": {
                      "value": "8867-4"
                    },
                    "display": {
                      "value": "Heart Rate"
                    }
                  }
                ],
                "text": {
                  "value": "heart_rate"
                }
              },
              "subject": {
                "patientId": {
                  "value": "example"
                },
                "display": {
                  "value": "Amy Shaw"
                }
              },
              "encounter": {
                "display": {
                  "value": "GP Visit"
                }
              },
              "effective": {
                "dateTime": {
                  "valueUs": "930873600000000",
                  "timezone": "UTC",
                  "precision": "DAY"
                }
              },
              "value": {
                "quantity": {
                  "value": {
                    "value": "1"
                  },
                  "unit": {
                    "value": "beats/min"
                  },
                  "system": {
                    "value": "http://unitsofmeasure.org"
                  },
                  "code": {
                    "value": "/min"
                  }
                }
              }
            }
          }
        ]
      }
    }
  ]
}