Brief Description of Measure:
​CMS128: Anti-depressant Medication Management:
Percentage of patients 18 years of age and older who were treated with antidepressant medication, had a diagnosis of major depression, and who remained on an antidepressant medication treatment. Two rates are reported.
a. Percentage of patients who remained on an antidepressant medication for at least 84 days (12 weeks).
b. Percentage of patients who remained on an antidepressant medication for at least 180 days (6 months).

Description of Issue:
The standards team expressed concerns with using 'Medication, Active' relevantPeriod to calculate cumulative medication duration as records may not contain a period stop date, which could incur an inaccurate duration calculation.
 
Since the measure intent is to assess continuous medication treatment after a dispensing event, 'Medication, Dispensed, is the most appropriate QDM datatype for calculating cumulative medication duration, as opposed to 'Medication, Order', which is not as close to actual administration.
 
Methods for calculating cumulative medication duration using Medication Dispensed are outlined in QDM 5.6 Section 5.7.3  (https://ecqi.healthit.gov/sites/default/files/QDM-v5.6-508.pdf).

Proposed Solution:
​//Before

define "Cumulative Medication Duration Greater Than or Equal to 180 Days":
  "Cumulative Medication Duration"("Antidepressant Medication Period In 231 Days After Initial Dispense")>= 180

define "Cumulative Medication Duration Greater Than or Equal to 84 Days":
  "Cumulative Medication Duration"("Antidepressant Medication Period In 114 Days After Initial Dispense")>= 84

define "Antidepressant Medication Period In 231 Days After Initial Dispense":
  ["Medication, Active": "Antidepressant Medication"] ActiveAntidepressant
    let ActiveMedPeriod: ActiveAntidepressant Meds
      return Meds.relevantPeriod
        intersect Interval[start of "Measurement Period" - 245 days,
        end of "Measurement Period"],
    InitialAntidepressantDispensed: "Earliest Antidepressant Dispensed 245 Days Before or 120 Days After Start of Measurement Period"
    where ActiveMedPeriod starts 231 days or less on or after day of InitialAntidepressantDispensed.relevantDatetime
    return ActiveMedPeriod
      intersect Interval[InitialAntidepressantDispensed.relevantDatetime, InitialAntidepressantDispensed.relevantDatetime + 231 days]

define "Antidepressant Medication Period In 114 Days After Initial Dispense":
  ["Medication, Active": "Antidepressant Medication"] ActiveAntidepressant
    let ActiveMedPeriod: ActiveAntidepressant Meds
      return Meds.relevantPeriod
        intersect Interval[start of "Measurement Period" - 245 days,
        end of "Measurement Period"],
    InitialAntidepressantDispensed: "Earliest Antidepressant Dispensed 245 Days Before or 120 Days After Start of Measurement Period"
    where ActiveMedPeriod starts 114 days or less on or after day of InitialAntidepressantDispensed.relevantDatetime
    return ActiveMedPeriod
      intersect Interval[InitialAntidepressantDispensed.relevantDatetime, InitialAntidepressantDispensed.relevantDatetime + 114 days]

define function "Cumulative Medication Duration"(Medication List<Interval<DateTime>> ):
  Sum((collapse(Medication))CumulativeAntidepressant
      return all duration in days of CumulativeAntidepressant
  )

//After

define "Cumulative Medication Duration Greater Than or Equal to 180 Days":
  "CumulativeDuration"("Antidepressant Medication Period In 231 Days After Initial Dispense")>= 180

define "Cumulative Medication Duration Greater Than or Equal to 84 Days":
  "CumulativeDuration"("Antidepressant Medication Period In 114 Days After Initial Dispense")>= 84

define "Antidepressant Medication Period In 114 Days After Initial Dispense":
["Medication, Dispensed": "Antidepressant Medication"] Antidepressant
  let IPSD: start of Global."NormalizeInterval" ( "Earliest Antidepressant Dispensed During Intake Period".relevantDatetime, "Earliest Antidepressant Dispensed During Intake Period".relevantPeriod ),
  MedicationPeriod: "MedicationDispensedPeriod"(Antidepressant)
  return MedicationPeriod
    intersect Interval[IPSD, IPSD + 114 days]

define "Antidepressant Medication Period In 231 Days After Initial Dispense":
["Medication, Dispensed": "Antidepressant Medication"] Antidepressant
  let IPSD: start of Global."NormalizeInterval" ( "Earliest Antidepressant Dispensed During Intake Period".relevantDatetime, "Earliest Antidepressant Dispensed During Intake Period".relevantPeriod ),
  MedicationPeriod: "MedicationDispensedPeriod"(Antidepressant)
  return MedicationPeriod
    intersect Interval[IPSD, IPSD + 231 days]

//Additional information about the "MedicationDispensedPeriod" and "CumulativeDuration" functions are available at: https://github.com/cqframework/CQL-Formatting-and-Usage-Wiki/blob/master/Source/Cooking%20With%20CQL/49/36_CumulativeMedicationDuration.cql.

Rationale for Change:
The goal of this change is to improve accuracy of cumulative medication duration calculation based on a dispensing event.