Outcome

increase

define "Initial Population":
  "Encounter with Creatinine and without Obstetrical Conditions"

define "Denominator":
  "Initial Population"

define "Denominator Exclusion":
  "Encounter with Less Than 2 Creatinine Results within 48 Hours of Arrival"
    union "Encounter with Index eGFR Less Than 60 within First 48 Hours"
    union "Encounter with 0.3 mg dL or More Increase in Creatinine"
    union "Encounter with Kidney Dialysis Started 48 Hours or Less After Arrival without High Creatinine"
    union "Encounter with High Risk Diagnosis for AKI"
    union "Encounter with High Risk Procedures for AKI"

define "Numerator":
  "Encounter with 2 Times Serum Creatinine Increase"
    union "Encounter with Kidney Dialysis Started More Than 48 Hours After Arrival without High Creatinine"

define "Encounter with Age 18 and Length of Stay 48 Hours or More":
  ["Encounter": "Encounter Inpatient"] InpatientEncounter
    where InpatientEncounter.period ends during day of "Measurement Period"
      and AgeInYearsAt(date from start of InpatientEncounter.period) >= 18
      and ( duration in hours of InpatientEncounter.hospitalizationWithObservation ( ) >= 48 )

define "Inpatient Encounter with Creatinine":
  from
    "Encounter with Age 18 and Length of Stay 48 Hours or More" Encounter48Hours,
    ["Observation": "Creatinine Mass Per Volume"] CreatinineTest
    let HospitalizationPeriod: Encounter48Hours.hospitalizationWithObservation ( ),
    CreatinineTestStart: CreatinineTest.effective.earliest ( )
    where CreatinineTest.value is not null
      and CreatinineTestStart during Interval[start of HospitalizationPeriod + 48 hours, end of HospitalizationPeriod]
      and CreatinineTest.status in { 'final', 'amended', 'corrected' }
    return Encounter48Hours

define "Encounter with Creatinine and without Obstetrical Conditions":
  "Inpatient Encounter with Creatinine" EncounterWithCreatinine
    where not exists ( ( EncounterWithCreatinine.encounterDiagnosis ( ) ) EncounterDiagnosis
        where EncounterDiagnosis.code in "Obstetrics and VTE Obstetrics"
    )

define "Serum Creatinine Normal":
  if ( Patient.gender = 'female' ) then 1.02 'mg/dL' 
    else if ( Patient.gender = 'male' ) then 1.18 'mg/dL' 
    else null

define "Qualifying Creatinine Lab Result by Time":
  from
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter,
    ["Observation": "Creatinine Mass Per Volume"] CreatinineTestByTime
    let CrEncId: QualifyingEncounter.id,
    CrHospPeriod: QualifyingEncounter.hospitalizationWithObservation ( ),
    CrLabId: CreatinineTestByTime.id,
    CrTime: CreatinineTestByTime.effective.earliest ( ),
    CrTimeIssued: CreatinineTestByTime.issued,
    CrResult: CreatinineTestByTime.value as Quantity,
    CrResultValue: CrResult.value,
    CrResultUnit: CrResult.unit
    where CrTime during CrHospPeriod
      and CreatinineTestByTime.isLaboratory ( )
      and CreatinineTestByTime.status in { 'final', 'amended', 'corrected' }
      and CrResultUnit = 'mg/dL'
      and CreatinineTestByTime.value is not null
      and CreatinineTestByTime.value as Quantity > 0 'mg/dL'
    return Tuple {
      CrEncInPtId: CrEncId,
      CrHospitalization: CrHospPeriod,
      CrLabObsId: CrLabId,
//                    LabCategory: CreatinineTestByQuantity.isLaboratory(),
      
      CrLabObsCategory: if CreatinineTestByTime.isLaboratory ( ) then 'laboratory' 
        else CreatinineTestByTime.isLaboratory ( ),
      CrLabObsStatus: CreatinineTestByTime.status,
      CrLabResult: CrResult,
      CrLabResultUnit: CrResultUnit,
      CrLabResultValue: CrResultValue,
      CrLabTime: CrTime,
      CrLabTimeIssued: CrTimeIssued
    }
    sort by CrLabTime

define "Encounter with 1.5 Times Serum Creatinine Increase":
  from
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter,
    ["Observation": "Creatinine Mass Per Volume"] HighCreatinineTest,
    ["Observation": "Creatinine Mass Per Volume"] LowCreatinineTest
    let LowCreatinineTestTime: LowCreatinineTest.effective.earliest ( ),
    HighCreatinineTestTime: HighCreatinineTest.effective.earliest ( ),
    HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation ( )
    where ( HighCreatinineTest.value > "Serum Creatinine Normal" )
      and LowCreatinineTest.status in { 'final', 'amended', 'corrected' }
      and HighCreatinineTest.status in { 'final', 'amended', 'corrected' }
      and HighCreatinineTest.value = "HighestSerumCreatinineResult"(QualifyingEncounter)
      and LowCreatinineTest.value = "LowestSerumCreatinineResult"(QualifyingEncounter)
      and "1.5IncreaseInCreatinine"(QualifyingEncounter) >= LowCreatinineTest.value
      and LowCreatinineTestTime 7 days or less before HighCreatinineTestTime
      and LowCreatinineTestTime during HospitalWithObservationPeriod
      and HighCreatinineTestTime during Interval[start of HospitalWithObservationPeriod + 48 hours, start of HospitalWithObservationPeriod + 30 days]
      and HighCreatinineTestTime during HospitalWithObservationPeriod
    return QualifyingEncounter

/*
define "Encounter with 1.5 Times Serum Creatinine Increase":
  from
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter,
    ["Observation": "Creatinine Mass Per Volume"] CreatinineTest
  let 
    LowestCreatinineTestWithin7DaysPrior: "LowestSerumCreatinineWithin7DaysPrior"(QualifyingEncounter, CreatinineTest),
    CreatinineTestTime: CreatinineTest.effective.earliest(),
    HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation()
  where 
    CreatinineTest.value >= LowestCreatinineTestWithin7DaysPrior * 1.5
    and CreatinineTest.value > "Serum Creatinine Normal"
    and CreatinineTestTime during Interval[start of HospitalWithObservationPeriod + 48 hours, start of HospitalWithObservationPeriod + 30 days]
  return QualifyingEncounter*/


define "Encounter with 2 Times Serum Creatinine Increase":
  from
    "Encounter with 1.5 Times Serum Creatinine Increase" EncounterWithHighCreatinine,
    ["Observation": "Creatinine Mass Per Volume"] HighCreatinineTest,
    ["Observation": "Creatinine Mass Per Volume"] LowCreatinineTest
    let LowCreatinineTestTime: LowCreatinineTest.effective.earliest ( ),
    HighCreatinineTestTime: HighCreatinineTest.effective.earliest ( ),
    HospitalWithObservationPeriod: EncounterWithHighCreatinine.hospitalizationWithObservation ( )
    where ( HighCreatinineTest.value > "Serum Creatinine Normal" )
      and LowCreatinineTest.status in { 'final', 'amended', 'corrected' }
      and HighCreatinineTest.status in { 'final', 'amended', 'corrected' }
      and HighCreatinineTest.value = "HighestSerumCreatinineResult"(EncounterWithHighCreatinine)
      and LowCreatinineTest.value = "LowestSerumCreatinineResult"(EncounterWithHighCreatinine)
      and ( "2.0IncreaseInCreatinine"(EncounterWithHighCreatinine) as Quantity ) >= ( LowCreatinineTest.value as Quantity )
      and LowCreatinineTestTime 7 days or less before HighCreatinineTestTime
      and LowCreatinineTestTime during HospitalWithObservationPeriod
      and HighCreatinineTestTime during Interval[start of HospitalWithObservationPeriod + 48 hours, start of HospitalWithObservationPeriod + 30 days]
      and HighCreatinineTestTime during HospitalWithObservationPeriod
    return EncounterWithHighCreatinine

define "Encounter with Kidney Dialysis Started More Than 48 Hours After Arrival":
  from
    ["Procedure": "Hospital Based Dialysis Services"] Dialysis,
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    let HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation ( )
    where Dialysis.performed.toInterval ( ) starts during Interval[start of HospitalWithObservationPeriod + 48 hours, end of HospitalWithObservationPeriod]
      and Dialysis.performed.toInterval ( ) starts during HospitalWithObservationPeriod
    return QualifyingEncounter

define "Encounter with Kidney Dialysis Started More Than 48 Hours After Arrival without High Creatinine":
  "Encounter with Kidney Dialysis Started More Than 48 Hours After Arrival" EncounterWithDialysisAfter48Hours
    where not ( exists ( "Encounter with 2 Times Serum Creatinine Increase" EncounterWithHighCreatinine
          where ( EncounterWithHighCreatinine.period includes EncounterWithDialysisAfter48Hours.period )
      )
    )

define "Numerator":
  "Encounter with 2 Times Serum Creatinine Increase"
    union "Encounter with Kidney Dialysis Started More Than 48 Hours After Arrival without High Creatinine"

define "Initial Population":
  "Encounter with Creatinine and without Obstetrical Conditions"

define "Denominator":
  "Initial Population"

define "Encounter with Less Than 2 Creatinine Results within 48 Hours of Arrival":
  "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    where ( Count("CreatinineLabTestwithResultwithinFirst48Hours"(QualifyingEncounter)) < 2 )

define "Male Encounter with eGFR Less Than 60":
  "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    where "MaleeGFR"(QualifyingEncounter) is not null
      and "MaleeGFR"(QualifyingEncounter) as Decimal < 60

define "Female Encounter with eGFR Less Than 60":
  "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    where "FemaleeGFR"(QualifyingEncounter) is not null
      and "FemaleeGFR"(QualifyingEncounter) as Decimal < 60

define "Encounter with Index eGFR Less Than 60 within First 48 Hours":
  "Male Encounter with eGFR Less Than 60"
    union "Female Encounter with eGFR Less Than 60"

define "Increase of 0.3 or More Using Lowest Creatinine within 24 Hours":
  from
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter,
    ["Observation": "Creatinine Mass Per Volume"] IndexCreatinineLabResult,
    ["Observation": "Creatinine Mass Per Volume"] SubsequentCreatinineLabResult
    let IndexCreatinineLabResultTime: IndexCreatinineLabResult.effective.earliest ( ),
    SubsequentCreatinineLabResultTime: SubsequentCreatinineLabResult.effective.earliest ( ),
    HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation ( )
    where IndexCreatinineLabResult.status in { 'final', 'amended', 'corrected' }
      and SubsequentCreatinineLabResult.status in { 'final', 'amended', 'corrected' }
      and ( ( SubsequentCreatinineLabResult.value as Quantity ) - ( IndexCreatinineLabResult.value as Quantity ) ) > 0.299 'mg/dL'
      and IndexCreatinineLabResult.value = "LowestSerumCreatinineResult"(QualifyingEncounter)
      and IndexCreatinineLabResultTime during Interval[SubsequentCreatinineLabResultTime - 48 hours, SubsequentCreatinineLabResultTime]
      and IndexCreatinineLabResultTime during HospitalWithObservationPeriod
      and IndexCreatinineLabResultTime during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 24 hours]
      and SubsequentCreatinineLabResultTime during HospitalWithObservationPeriod
      and SubsequentCreatinineLabResultTime during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 48 hours]
      and IndexCreatinineLabResult.id != SubsequentCreatinineLabResult.id
    return QualifyingEncounter

define "Increase of 0.3 or More Using First Creatinine within First 48 Hours":
  from
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter,
    ["Observation": "Creatinine Mass Per Volume"] IndexCreatinineLabResult,
    ["Observation": "Creatinine Mass Per Volume"] SubsequentCreatinineLabResult
    let IndexCreatinineLabResultTime: IndexCreatinineLabResult.effective.earliest ( ),
    SubsequentCreatinineLabResultTime: SubsequentCreatinineLabResult.effective.earliest ( ),
    HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation ( )
    where IndexCreatinineLabResult.status in { 'final', 'amended', 'corrected' }
      and SubsequentCreatinineLabResult.status in { 'final', 'amended', 'corrected' }
      and ( ( SubsequentCreatinineLabResult.value as Quantity ) - ( IndexCreatinineLabResult.value as Quantity ) ) > 0.299 'mg/dL'
      and IndexCreatinineLabResult.value as Quantity = singleton from "EarliestSerumCreatinineResult"(QualifyingEncounter)
      and IndexCreatinineLabResultTime during Interval[SubsequentCreatinineLabResultTime - 48 hours, SubsequentCreatinineLabResultTime]
      and IndexCreatinineLabResultTime during HospitalWithObservationPeriod
      and SubsequentCreatinineLabResultTime during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 48 hours]
      and SubsequentCreatinineLabResultTime during HospitalWithObservationPeriod
      and IndexCreatinineLabResultTime during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 48 hours]
      and SubsequentCreatinineLabResultTime during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 48 hours]
      and IndexCreatinineLabResult.id != SubsequentCreatinineLabResult.id
    return QualifyingEncounter

define "Encounter with 0.3 mg dL or More Increase in Creatinine":
  Coalesce("Increase of 0.3 or More Using Lowest Creatinine within 24 Hours", "Increase of 0.3 or More Using First Creatinine within First 48 Hours")

define "Encounter with Kidney Dialysis Started 48 Hours or Less After Arrival":
  from
    ["Procedure": "Hospital Based Dialysis Services"] Dialysis,
    "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    let HospitalWithObservationPeriod: QualifyingEncounter.hospitalizationWithObservation ( )
    where Dialysis.performed.toInterval ( ) starts during Interval[start of HospitalWithObservationPeriod, start of HospitalWithObservationPeriod + 48 hours]
      and Dialysis.performed.toInterval ( ) starts during HospitalWithObservationPeriod
    return QualifyingEncounter

define "Encounter with Kidney Dialysis Started 48 Hours or Less After Arrival without High Creatinine":
  "Encounter with Kidney Dialysis Started 48 Hours or Less After Arrival" EncounterWithKidneyDialysis48HoursOrAfter
    where not ( exists ( "Encounter with 2 Times Serum Creatinine Increase" EncounterWithHighCreatinine
          where ( EncounterWithHighCreatinine.period includes EncounterWithKidneyDialysis48HoursOrAfter.period )
      )
    )

define "Encounter with High Risk Diagnosis for AKI":
  "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    where exists ( ( QualifyingEncounter.encounterDiagnosis ( ) ) EncounterDiagnosis
        where ( EncounterDiagnosis.code in "High Risk Diagnosis for AKI" )
    )

define "Encounter with High Risk Procedures for AKI":
  "Encounter with Creatinine and without Obstetrical Conditions" QualifyingEncounter
    with ["Procedure": "High Risk Procedures for AKI"] HighRiskProcedures
      such that HighRiskProcedures.performed.toInterval ( ) starts during QualifyingEncounter.hospitalizationWithObservation ( )

define "Denominator Exclusion":
  "Encounter with Less Than 2 Creatinine Results within 48 Hours of Arrival"
    union "Encounter with Index eGFR Less Than 60 within First 48 Hours"
    union "Encounter with 0.3 mg dL or More Increase in Creatinine"
    union "Encounter with Kidney Dialysis Started 48 Hours or Less After Arrival without High Creatinine"
    union "Encounter with High Risk Diagnosis for AKI"
    union "Encounter with High Risk Procedures for AKI"

/*
@description: Converts the given [Period](https://hl7.org/fhir/datatypes.html#Period)
value to a CQL DateTime Interval
@comment: If the start value of the given period is unspecified, the starting
boundary of the resulting interval will be open (meaning the start of the interval
is unknown, as opposed to interpreted as the beginning of time).
*/
define function ToInterval(period FHIR.Period):
    if period is null then
        null
    else
        if period."start" is null then
            Interval(period."start".value, period."end".value]
        else
            Interval[period."start".value, period."end".value]

/*
@description: Hospitalization with Observation returns the total interval from the start of any immediately prior emergency department visit through the observation visit to the discharge of the given encounter
*/
define fluent function hospitalizationWithObservation(TheEncounter Encounter ):
  TheEncounter Visit
  		let ObsVisit: Last([Encounter: "Observation Services"] LastObs
  				where LastObs.status = 'finished'
            and LastObs.period ends 1 hour or less on or before start of Visit.period
  				sort by end of period
  			),
  			VisitStart: Coalesce(start of ObsVisit.period, start of Visit.period),
  			EDVisit: Last([Encounter: "Emergency Department Visit"] LastED
  				where LastED.status = 'finished'
            and LastED.period ends 1 hour or less on or before VisitStart
  				sort by end of period
  			)
  		return Interval[Coalesce(start of EDVisit.period, VisitStart), end of Visit.period]

/*
@description: Given an interval, return the starting point if the interval has a starting boundary specified,
otherwise, return the ending point
*/
define fluent function earliest(choice Choice<DateTime, Quantity, Interval<DateTime>, Interval<Quantity>> ):
  (choice.toInterval()) period
    return
      if (period."hasStart"()) then start of period
      else end of period

/*
@description: Given an interval, return true if the interval has a starting boundary specified
(i.e. the start of the interval is not null and not the minimum DateTime value)
*/
define fluent function hasStart(period Interval<DateTime> ):
  not ( start of period is null
      or start of period = minimum DateTime
  )

/*
@description: Returns the Condition resources referenced by the diagnosis element of the Encounter
*/
define fluent function encounterDiagnosis(Encounter Encounter ):
  Encounter.diagnosis D
    return singleton from ([Condition] C where C.id = D.condition.reference.getId())

/*
@description: Returns the tail of the given uri (i.e. everything after the last slash in the URI).
@comment: This function can be used to determine the logical id of a given resource. It can be used in
a single-server environment to trace references. However, this function does not attempt to resolve
or distinguish the base of the given url, and so cannot be used safely in multi-server environments.
*/
define fluent function getId(uri String):
  Last(Split(uri, '/'))

define function "HighestSerumCreatinineResult"(QualifyingEncounter Encounter):
  ( Max((from
          "Qualifying Creatinine Lab Result by Time" LabTests
          let LabResult: LabTests.CrLabResult
          where LabTests.CrEncInPtId = QualifyingEncounter.id
      ).CrLabResult
    )
  )

/*
@description: Returns true if the given observation is a laboratory observation
*/
define fluent function isLaboratory(observation Observation):
  exists (observation.category C
    where C ~ "laboratory"
  )

/*
@description: Converts the given FHIR [CodeableConcept](https://hl7.org/fhir/datatypes.html#CodeableConcept) value to a CQL Concept.
*/
define function ToConcept(concept FHIR.CodeableConcept):
    if concept is null then
        null
    else
        System.Concept {
            codes: concept.coding C return ToCode(C),
            display: concept.text.value
        }

/*
@description: Converts the given FHIR [Coding](https://hl7.org/fhir/datatypes.html#Coding) value to a CQL Code.
*/
define function ToCode(coding FHIR.Coding):
    if coding is null then
        null
    else
        System.Code {
          code: coding.code.value,
          system: coding.system.value,
          version: coding.version.value,
          display: coding.display.value
        }

define function "LowestSerumCreatinineResult"(QualifyingEncounter Encounter):
  ( Min((from
          "Qualifying Creatinine Lab Result by Time" LabTests
          let LabResult: LabTests.CrLabResult
          where LabTests.CrEncInPtId = QualifyingEncounter.id
      ).CrLabResult
    )
  )

// following functions work with Cr result as Quantity (not decimal, but Quantity value is decimal)


define function "1.5IncreaseInCreatinine"(QualifyingEncounter Encounter):
  "HighestSerumCreatinineResult"(QualifyingEncounter) / 1.5

define function "2.0IncreaseInCreatinine"(QualifyingEncounter Encounter):
  "HighestSerumCreatinineResult"(QualifyingEncounter) / 2

define function "CreatinineLabTestwithResultwithinFirst48Hours"(QualifyingEncounter Encounter):
  from
    ["Observation": "Creatinine Mass Per Volume"] CreatinineTest
    where CreatinineTest.value is not null
      and CreatinineTest.effective.earliest ( ) during Interval[start of QualifyingEncounter.hospitalizationWithObservation ( ), start of QualifyingEncounter.hospitalizationWithObservation ( ) + 48 hours]
      and CreatinineTest.effective.earliest ( ) during QualifyingEncounter.hospitalizationWithObservation ( )
      and CreatinineTest.status in { 'final', 'amended', 'corrected' }
    return CreatinineTest

define function "MaleeGFR"(QualifyingEncounter Encounter):
  if Patient.gender = 'male' then ( 142 * Min({("IndexCreatinine"(QualifyingEncounter).value / 0.9), 1 }) ^ ( - 0.302 ) * Max({("IndexCreatinine"(QualifyingEncounter).value / 0.9), 1 }) ^ ( - 1.200 ) * 0.9938 ^ ( AgeInYearsAt(start of QualifyingEncounter.hospitalizationWithObservation()) ) ) 
    else null

define function "IndexCreatinine"(QualifyingEncounter Encounter):
  Coalesce("LowestSerumCreatinineIn24Hours"(QualifyingEncounter), singleton from "FirstSerumCreatinineIn48Hours"(QualifyingEncounter))

define function "LowestSerumCreatinineIn24Hours"(QualifyingEncounter Encounter):
  Min((from
        "Qualifying Creatinine Lab Result by Time" LabTestsLow
        let LabResult: LabTestsLow.CrLabResult
        where LabTestsLow.CrEncInPtId = QualifyingEncounter.id
          and LabTestsLow.CrLabTime during Interval[start of QualifyingEncounter.hospitalizationWithObservation(), start of QualifyingEncounter.hospitalizationWithObservation() + 24 hours]
    ).CrLabResult
  )

// find result from earliest time in 48 hrs


define function "FirstSerumCreatinineIn48Hours"(QualifyingEncounter Encounter):
  from
    "Qualifying Creatinine Lab Result by Time" LabTests
    let LabResult: LabTests.CrLabResult
    where ( "EarliestSerumCreatinineTimeIn48Hours"(QualifyingEncounter) = LabTests.CrLabTime )
    return LabResult as Quantity

// find earliest time in 48 hrs


define function "EarliestSerumCreatinineTimeIn48Hours"(QualifyingEncounter Encounter):
  ( Min((from
          "Qualifying Creatinine Lab Result by Time" LabTests48
          let LabResult48: LabTests48.CrLabResult
          where LabTests48.CrEncInPtId = QualifyingEncounter.id
            and LabTests48.CrLabTime during Interval[start of QualifyingEncounter.hospitalizationWithObservation(), start of QualifyingEncounter.hospitalizationWithObservation() + 48 hours]
      ).CrLabTime
    )
  )

// eGFR functions return as decimal value rather than Quantity


define function "FemaleeGFR"(QualifyingEncounter Encounter):
  if Patient.gender = 'female' then ( 142 * Min({("IndexCreatinine"(QualifyingEncounter).value / 0.7), 1 }) ^ ( - 0.241 ) * Max({("IndexCreatinine"(QualifyingEncounter).value / 0.7), 1 }) ^ ( - 1.200 ) * 0.9938 ^ ( AgeInYearsAt(start of QualifyingEncounter.hospitalizationWithObservation()) ) * 1.012 ) 
    else null

define function "EarliestSerumCreatinineResult"(QualifyingEncounter Encounter):
  from
    "Qualifying Creatinine Lab Result by Time" LabTests
    let LabResult: LabTests.CrLabResult
    where ( "EarliestSerumCreatinineTime"(QualifyingEncounter) = LabTests.CrLabTime )
    return LabResult as Quantity

define function "EarliestSerumCreatinineTime"(QualifyingEncounter Encounter):
  ( Min((from
          "Qualifying Creatinine Lab Result by Time" LabTestsEarly
          let LabResultEarly: LabTestsEarly.CrLabResult
          where LabTestsEarly.CrEncInPtId = QualifyingEncounter.id
      ).CrLabTime
    )
  )