Answer: Birth Date
Explanation: A limited data set is middle ground between identifiable and de-identified information. In a limited data set, most identifying information has been removed. It must not include any of the individual identifiers [45 CFR 164.514(e)]. Limited data sets don’t directly identify a patient, but they may contain some identifiers. The following identifiers may be included as part of a limited data set:
* Geographic data (town, city, state, and ZIP code, but no street address)
* Dates relating to an individual (birth date, admission and discharge dates)
* Unique identifying numbers, characteristics, or codes other than those listed under individual identifiers