KEY_ED is an HCUP record identifier created specifically for the Nationwide Emergency Department Sample (NEDS). Its purpose is to uniquely identify records so that the data elements from different NEDS files can be combined. KEY_ED does not link to other HCUP databases or to external databases.

KEY_ED is a unique record identifier and cannot be used to track a person over time.

Prior to data year 2023, the first digit of KEY_ED identifies the Census region. Starting in data year 2023, information on Census region is excluded.