New releases of QDM must be expressible in HQMF R2.1. While HQMF R2.1 is a notable improvement over HQMF R1, some concepts that were expressible in QDM R1 are no longer expressible in QDM R2.1.

Median and Average

The median and average operators are not supported in HQMF R2.1 for defining measure populations. For example:

AND: Average < 140 mmHg of: "Physical Exam, Performed: Systolic Blood Pressure (result)" during "Measurement Period"

Median and Average are still supported in the Measure Observation section.

Impact: Median and Average are not currently used in any measure population definitions in published MU-2 measures.

Solution: Create QDM extension to HQMF to support the MEDIAN and AVERAGE subset codes in data criteria excerpt. From a QDM user perspective, there is no change.

DateDiff and TimeDiff

The difference between dates and time difference operators are not supported in HQMF R2.1 for defining measure populations or measure observations. For example, this can no longer be expressed in HQMF R2.1:

AND: Difference between dates < 2 days of:
    AND: "Occurrence A of Encounter, Performed: Inpatient (facility location arrival datetime)"
    AND: "Occurrence A of Encounter, Performed: Inpatient (facility location departure datetime)"

Impact for Measure Populations: DateDiff is currently used in measure population definitions in CMS 72 and CMS 73, but TimeDiff is not used in any measure populations.

Solution for Measure Populations: Remove QDM support for DateDiff/TimeDiff in defining measure populations. In most cases, the same concept can be expressed without the DateDiff or TimeDiff operator. For example, the above could be expressed as:

AND: "Occurrence A of Encounter, Performed: Inpatient (facility location arrival datetime)" < 2 day(s) starts before end of "Occurrence A of Encounter, Performed: Inpatient (facility location departure datetime)"

CMS 72 and CMS 73 would need to be rewritten to replace the DateDiff operator with equivalent logic.

Impact for Measure Observations: DateDiff is not used in any measure observation definitions in published MU-2 measures, but TimeDiff is used in measure observation definitions for CMS 32, CMS 55, and CMS 111.

Solution for Measure Observations: Continue to support DateDiff/TimeDiff in Measure Observations by expressing it with javascript using HQMF R2.1's new expression support. From a QDM user perspective, there is no change.

DateDiff and TimeDiff --> DateTimeDiff

It has been noted that there is no significant difference between DateDiff and TimeDiff. With that in mind, the QDM User Group recommended merging DateDiff and TimeDiff into one function: DatetimeDiff. This function, however, will still be available only in MeasureObservations.

Median of: Datetime difference of:
    AND: "Occurrence A of Encounter, Performed: Emergency Department Visit (facility location arrival datetime)"
    AND: "Occurrence A of Encounter, Performed: Emergency Department Visit (facility location departure datetime)"