The Tri Council Policy Statement (TCPS 2) defines identifiable information as follows:

Information that may reasonably be expected to identify an individual, alone or in combination with other available information, is considered identifiable information…

It goes on to further categorize identifiable information.

• Directly identifying information – the information identifies a specific individual through direct identifiers (e.g., name, social insurance number, personal health number).

• Indirectly identifying information – the information can reasonably be expected to identify an individual through a combination of indirect identifiers (e.g., date of birth, place of residence or unique personal characteristic).

• Coded information – direct identifiers are removed from the information and replaced with a code. Depending on access to the code, it may be possible to re-identify specific participants (e.g., the principal investigator retains a list that links the participants’ code names with their actual name so data can be re-linked if necessary).

• Anonymized information – the information is irrevocably stripped of direct identifiers, a code is not kept to allow future re-linkage, and risk of re-identification of individuals from remaining indirect identifiers is low or very low.

• Anonymous information – the information never had identifiers associated with it (e.g., anonymous surveys) and risk of identification of individuals is low or very low.

Examples of Identifiers

The US Government’s Health Insurance Portability and Accountability Act (HIPPA) contains useful examples of data items that constitute identifiers. These may be categorized as either direct or indirect identifiers. This categorization is not intended to be definitive but should be considered as guidance for investigators when considering the context of their own study data.