Initial question posed by Lisa Nelson:
The measure’s definition in theSpecification Manual for National Hospital Inpatient Quality Measures (version 5a) uses the concepts of Arrival Date, Arrival Time, and ED Departure Date, ED to compute the difference used in median calculation. The definition for ED Departure Date is: The month, day, and year at which the patient departed from the emergency department, and the definition for ED Departure Time is: The time (military time) represented in hours and minutes at which the patient departed from the emergency department (page 1-135). The definition for Arrival Date is: The earliest documented month, day, and year the patient arrived at the hospital, Arrival Time is: The earliest documented time (military time) the patient arrived at the hospital.

When we go into QDM 4.2 to find similar temporal concepts, we find there are four available for an Encounter, Performed:
Temporal attribute available for an Encounter, Performed
QDM 4.2 definition
Facility Location Arrival Datetime

The time that the patient arrived at the specific facility for the encounter.
Facility Location Departure Datetime

The time that the patient departed the specific facility related to the encounter.
Admission Datetime

The start date and time for admission to an encounter in an inpatient setting. This attribute should not be used for outpatient encounters.

Discharge Datetime

The date and time that the patient was discharged from an inpatient encounter. This attribute should not be used for outpatient encounters.

Note that Encounter, Performed does not include the following two attributes:
Temporal attribute NOT available for an Encounter, Performed
QDM 4.2 definition
Start Datetime

The time the indicated event starts. In the case of Order datatypes, this is the “author time” (when the order was signed).

Stop Datetime

The time the indicated event ends. In the case of Order datatypes, this corresponds to the QRDA “author time” (when the order was signed).

The problem arises because the ED-1 Measure Population is constrained to include Inpatient Encounters where there was a prior Emergency Department Visit (within a specified time period) that occurred at the same facility. This means that ED-1 is constrained to situations where the patient arrives at the facility, has an encounter in the ED which is followed by an Inpatient Encounter at the same facility. The patient does not leave the facility. Their ED visit and inpatient care happen at the same facility.

The problem is that there does not appear to be an appropriate temporal attribute to indicate the end-point of the Encounter, Performed for an Emergency Department visit that is part of an episode of care which results in an inpatient encounter at the same facility. Facility Location Departure Datetime is not correct because the patient does not leave the facility at the end of the ED Visit. Discharge Datetime is not correct because the patient is not being discharged from an inpatient encounter and the definition says it should not be used for outpatient encounters. Stop Datetime is not available for use with the Encounter, Performed datatype.
Measure Observation =
Median of:
Datetime difference of:
"Occurrence A of Encounter, Performed: Emergency Department Visit (????????????)"
"Occurrence A of Encounter, Performed: Emergency Department Visit (facility location arrival datetime)"

What do you recommend we do to specify a suitable temporal end-point for the measure observation in ED-1?