Table 1.

Aggregated list of potential patient identifiers in datasets (Hrynaskiewicz [15])

Direct identifiers	Indirect identifiers
01. Name	A. Place of treatment or health professional responsible for care
02. Initials	B. Sex
03. Address, including full or partial postal code	C. Rare disease or treatment
04. Telephone or fax numbers or contact information	D. Sensitive data, such as illicit drug use or ‘risky behaviour’
05. Electronic mail addresses	E. Place of birth
06. Unique identifying numbers	F. Socioeconomic data, such as occupation or place of work, income, or education
07. Vehicle identifiers	G. Household and family composition
08. Medical device identifiers	H. Anthropometry measures
09. Web or internet protocol addresses	I. Multiple pregnancies
10. Biometric data	J. Ethnicity
11. Facial photograph or comparable image	K. Small denominators – population size of < 100
12. Audiotapes	L. Very small numerators – event counts of < 3
13. Names of relatives	M. Year of birth or age
14. Dates related to an individual (including date of birth)	N. Verbatim responses or transcripts
Superfluous
02. Superfluous information (audit trail data, administration data)