The “initiates” and “terminates” operators provide an inverse of the “starts during” and “ends during” operators. These operators provide the same functionality of the starts and ends during operators, but they allow the right hand and left hand side of the temporal relationship to be swapped. The introduction of these operators is important because it allows measures to be specified from the context of an encounter. Without the initiates and terminates operators, logic must often specify the target encounter both directly and indirectly. For instance, consider the following logic:

AND: Occurrence A of Encounter X during the Measure Period
AND: Occurrence A of Encounter X (length of stay < 120 days)
AND: Diagnosis, Active Y starts during Occurrence A of Encounter X

The first two logic statements above specify the target encounter directly by providing logic that filters the encounters associated with the patient. However, the third statement indirectly identifies the encounter by having it relative to the diagnoses on the patient. Using the “initiates” operator, all statements can be directly specified relative to the encounter.

AND: Occurrence A of Encounter X during the Measure Period
AND: Occurrence A of Encounter X (length of stay < 120 days)
AND: Occurrence A of Encounter X initiates Diagnosis, Active Y

While this may seem like a trivial distinction, it allows measures to focus more closely on identifying target encounters. This is of particular value for episode of care measures that identify an encounter to use as a basis for the evaluation of the measure logic. Additionally, with the introduction of the “satisfies” selectors (see QDM-4), the initiates and terminates operators would allow the target encounter to be identified with a single satisfies condition rather than relying on three separate logical conditions.