Special Epic versus Legacy Considerations

Name	Description
Data Domain:	Medication Orders
Data Type:	Numeric and Text
Definition	Epic and Legacy medication data differs in the following important ways: In Epic data, medication information is associated with specific encounters; this relationship is carried over into i2b2. In Legacy data, medication information is at the patient level with no specific link to an individual encounter. Legacy data includes outpatient and discharge medications only; legacy inpatient drug orders are not available in i2b2, but may be available in the CDW-H by request. Most of the Medication Modifiers (see ‘Medication Modifiers’, below) do not apply to legacy medications, other than the “Discharge Medication Indicator,” which is available for legacy medications. Thus, if constraining on a modifier other than Discharge Medication, you may inadvertently drop legacy medications from your dataset. To accommodate the fact that Epic medications are linked to encounters and Legacy medications are linked to patients, we have created a single “shell” legacy encounter for each patient that holds all of their legacy medication orders. This can affect how you query when you want to use the “Selected group occur in the same encounter” constraint in i2b2., Remember that legacy medications will not connect to any additional information since they are “shell” encounters that have been created to hold the patient’s legacy medication history Tip! Our recommendations for how to query on medications spanning legacy and Epic data in the same query are: Build specific patient sets that apply your medication criteria separate from other criteria OR Apply date constraints to all of your criteria and use a temporal constraint of “Treat Independently”
Source:	Epic and Legacy