Many QDM datatypes contain attributes that represent date/times. These attributes often align with an effective start or end time for the element (for example, Encounter, Performed (discharge datetime) maps to Encounter, Performed's effective end time).

In this regard, certain attributes do not make sense with certain timing relationships. For example, it does not make sense for an end date to "start before" something (e.g., Encounter, Performed (discharge datetime) starts before start of "Measurement Period" does not make sense since discharge datetime is an end date). Aligning end dates with "start" relationships or start dates with "end" relationships causes problems for mapping to HQMF R2.1.

Mapping of date attributes to their datatype's effective start / end times

When possible, measure developers should avoid using timing relationships with attributes when the same concept can be expressed without the attribute. For example, prefer Encounter, Performed ends before start of "Measurement Period" rather than Encounter, Performed (discharge datetime) ends before start of "Measurement Period". These mappings will be defined in the QDM specification so that measure authors understand what timing relationships to use.

Date attributes that do not map to their datatype's effective start / end time

Some attributes do not map directly to their datatype's effective start or end times (for example, Procedure, Performed (incision datetime)). In these cases, measure authors should still be careful to use the correct timing relationships based on the HQMF mappings. These mappings will be defined in the QDM specification