Medication, Order includes a frequency attribute defined in QDM 5.3 (and 5.4) as: 

• Indicates how frequently the medication or substance
  • Is administered to a patient for an active medication (Medication, Active).
  • Was administered to the patient (Medication, Administered; Substance, Administered).
  • Should be taken by the patient or administered to the patient (Medication, Discharge; Medication, Dispensed; Medication, Order; Substance, Order).
  • Is recommended to be given to the patient (Substance, Recommended).

In defining the QDM for a measure calculating Opioid usage that must calculate 'morphine milligram equivalents' the measure developer used the 'frequency' attribute to calculate maximum dosage.  Since frequency may be narrative or numerical (e.g., 4 times per day, every 6 hours, etc.) the QDM model info uses a code to represent the various options for the frequency field and then the CQL converts the code to a number for the calculation.  The challenge is defining the maximum dose when considering 'as needed', or "PRN" medications. Often the frequency for PRN medications includes a range such as "every 4-6 hours". The CQL expression for the current measure logic identifies the most frequent administration (i.e., every 4 hours).  However, QDM does not allow a range for frequency.

Recommend adding a range for frequency modeled similar to the reference range high and reference range low for laboratory tests:

Frequency range high - i.e., most frequent

Frequency range low - i.e., least frequent

The change would allow measures to specify the calculation based on the QDM model more directly. The frequency maps to HL7 FHIR MedicationRequest.dosageInstruction (http://hl7.org/fhir/medicationrequest-definitions.html#MedicationRequest.dosageInstruction).