De-identification is the process by which a collection of data is stripped of information which would allow the identification of the source of the data. Common uses of de-identification include human subject research for the sake of privacy for research participants. Common strategies for de-identifying datasets are deleting or masking personal identifiers, such as name and social security number, and suppressing or generalizing quasi-identifiers, such as date of birth and zip code. The reverse process of defeating de-identification to identify individuals is known as re-identification.
A survey is conducted, such as a census, to collect information about a group of people. To encourage participation and to protect the privacy of survey respondents, the researchers attempt to design the survey in such a way that people can participate in the survey and when the result is published it will not be possible to match any participant's individual response with any data published in the result.
Anonymization and de-identification
Anonymization refers to irreversibly severing a data set from the identity of the data contributor in a study to prevent any future re-identification, even by the study organizers under any condition. De-identification is also a severing of a data set from the identity of the data contributor, but may include preserving identifying information which could only be re-linked by a trusted party in certain situations.
Whenever a person participates in genetics research the donation of a biological specimen often results in the creation of a large amount of personalized data. Such data is uniquely difficult to de-identify.
Anonymization of genetic data is particularly difficult because of the huge amount of genotypic information in biospecimens, the ties that specimens often have to medical history, and the advent of modern bioinformatics tools for data mining. There have been demonstrations that data for individuals in aggregate collections of genotypic data sets can be tied to the identities of the specimen donors.
Some researchers have suggested that it is not reasonable to ever promise participants in genetics research that they can retain their anonymity, but instead such participants should be taught the limits of using coded identifiers in a de-identification process.
De-identification laws in the United States of America
Sometimes a researcher will have data about human subjects of significance to other researchers and want to share that data. A common case is that hospitals collect large amounts of medical statistics on their patients and it would be useful for medical research for other entities to review that data. In this case, it would be unethical to reveal the identities of the people whose data would be shared, because those people have a right to privacy. In order to share the data, it must first be de-identified so that no particular person can be associated with their data set by anyone who sees the data.
The problem is that it is hard to determine what kind of data can identify a person. One model for determining what data cannot be shared is the United States' policy on protected health information, which gives a list of identifying data. If a researcher removes protected health information from a data set, then the term for that researcher's state is that the researcher is in a "safe harbor" for having taken reasonable action to protect the identities of those whose data the researchers collected.
Research on decedents
The key law about research in electronic health record data is HIPAA Privacy Rule. This law allows use of electronic health record of deceased subjects for research (HIPAA Privacy Rule (section 164.512(i)(1)(iii)))
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- 45 C.F.R. 164.512)
- a training series on United States government de-identification standards