Protected health information

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Protected health information (PHI) is any information about health status, provision of health care, or payment for health care that can be linked to a specific individual. This is interpreted rather broadly[dubious ] and includes any part of a patient's medical record or payment history.

PHI is often sought out in datasets for de-identification before researchers share the dataset publicly. When researchers remove PHI from a dataset they do so in an attempt to preserve privacy for research participants.

United States[edit]

Under the US Health Insurance Portability and Accountability Act (HIPAA), PHI that is linked based on the following list of 18 identifiers must be treated with special care:[1]

  1. Names
  2. All geographical identifiers smaller than a state, except for the initial three digits of a zip code if, according to the current publicly available data from the Bureau of the Census: the geographic unit formed by combining all zip codes with the same three initial digits contains more than 20,000 people; and the initial three digits of a zip code for all such geographic units containing 20,000 or fewer people is changed to 000
  3. Dates (other than year) directly related to an individual
  4. Phone numbers
  5. Fax numbers
  6. Email addresses
  7. Social Security numbers
  8. Medical record numbers
  9. Health insurance beneficiary numbers
  10. Account numbers
  11. Certificate/license numbers
  12. Vehicle identifiers and serial numbers, including license plate numbers;
  13. Device identifiers and serial numbers;
  14. Web Uniform Resource Locators (URLs)
  15. Internet Protocol (IP) address numbers
  16. Biometric identifiers, including finger, retinal and voice prints
  17. Full face photographic images and any comparable images
  18. Any other unique identifying number, characteristic, or code except the unique code assigned by the investigator to code the data

De-identification versus anonymization[edit]

Anonymization is a process in which PHI elements are eliminated or manipulated with the purpose of hindering the possibility of going back to the original data set.[2] This involves removing all identifying data to create unlinkable data.[3] De-identification under the Health Insurance Portability and Accountability Act Privacy rule occurs when data has been stripped of common identifiers by two methods:

  1. The removal of 18 specific identifiers (Safe Harbor Method):
  • Names
  • Geographic data
  • All elements of dates
  • Telephone numbers
  • FAX numbers
  • Email addresses
  • Social Security numbers
  • Medical record numbers
  • Health plan beneficiary numbers
  • Account numbers
  • Certificate/license numbers
  • Vehicle identifiers and serial numbers including license plates
  • Device identifiers and serial numbers
  • Web URLs
  • Internet protocol addresses
  • Biometric identifiers (i.e. retinal scan, fingerprints)
  • Full face photos and comparable images
  • Any unique identifying number, characteristic or code
2. Obtain the expertise of an experienced statistical expert to validate and document the statistical risk of re-identification is very small (Statistical Method).[4][5]

De-identified data is coded, with a link to the original, fully identified data set kept by an honest broker. Links exist in coded de-identified data making the data considered indirectly identifiable and not anonymized. Coded de-identified data is not protected by the HIPAA Privacy Rule, but is protected under the Common Rule. The purpose of de-identification and anonymization is to use health care data in larger increments, for research purposes. Universities, government agencies, and private health care entities use such data for research, development and marketing purposes.[3]


  1. ^ "De-identification". 2011. Retrieved 9 December 2011. safe 
  2. ^ Ohm, Paul (August 2010). "Broken Promises of Privacy: Responding to the Surprising Failure of Anonymization". UCLA Law Review 57 (6): 1701–1777. 
  3. ^ a b
  4. ^ "Encouraging the Use of, and Rethinking Protections for De-Identified (and "Anonymized") Health Data" (PDF). Center for Democracy and Technology. June 2009. Retrieved June 12, 2014. 
  5. ^ "HIPAA: What? De-identification of Protected Health Information (PHI)". HIPAA Research Guide. University of Wisconsin-Madison. August 26, 2003. Retrieved June 12, 2014. 

Further reading[edit]