Metadata—structured information that describes, explains,
locates, and otherwise makes it easier to retrieve and use
an information resource.
Administrative metadata—metadata related to the use,
management, and encoding processes of digital objects
over a period of time.
Descriptive metadata—metadata that describes a work
for purposes of discovery and identification, such as creator, title, and subject.
Structural metadata—metadata that indicates how
compound objects are structured, provided to support
use of the objects.
Scheme (schema)—a metadata element set and rules
for using it.
Semantics—the names and meanings of metadata elements.
Syntax—rules for how metadata elements and their content are encoded.
Metadata schemes (also called schema) are sets of metadata elements designed for a specific purpose, such as describing a particular type of information resource. The definition or meaning of the elements themselves is known as
the semantics of the scheme. The values given to metadata elements are the content. Metadata schemes generally specify names of elements and their semantics.
There may also be syntax rules for how the elements
and their content should be encoded. Metadata can be
encoded in any definable syntax. Many current metadata
schemes use SGML (Standard Generalized Mark-up Language) or XML (Extensible Mark-up Language).
Excerpted from: National Information Standards Organization. “Understanding Metadata.” 2004. www.niso.org.
Metadata’s Uses in Healthcare
Metadata have application in healthcare at any point where
they may provide useful information about a particular piece of
health data. This includes indexing information for storage and
retrieval as well as describing data when exchanging it beyond
the facility walls.
The best way to manage data for advanced data mining,
PCAST wrote, is to “break it down into the smallest individual
pieces that make sense to exchange or aggregate.” The authors
call these pieces “tagged data elements,” because “each unit of
data is accompanied by a mandatory ‘metadata tag’ that de-
scribes the attributes, provenance, and required privacy protec-
tions of the data.”
Metadata can be developed and managed through a metadata
repository that indexes and consolidates metadata from differ-
ent documents and information systems. From there the re-
pository can integrate with an electronic health record system.
Queries against a patient name will retrieve all relevant data for
In this manner, metadata can be used in a decision support
tool to identify contradicting medications, allergies, and other
factors that would affect the patient’s care. Take for example a
physician using a medication system that is not tied to other aspects of the patient’s record and does not reflect the patient’s
other disease states. If the physician prescribes the patient aspirin for a chronic headache, metadata could be used to retrieve
other patient information, alerting the physician that the patient currently takes a blood thinner.
On the other hand, metadata could be viewed as a security
vulnerability. If not secured, they could expose information and
software assets to theft or infiltration via hijacking, compromised certification, or viruses. In healthcare, breach of information can lead to damaging disclosure of confidential patient
Metadata can provoke controversy related to confidentiality,
compliance, and litigation because they can be used to confirm
who has seen or edited a record and in some cases establish a
series of actions. This can benefit physicians by giving them a
more accurate picture of the sequence of events in a patient file.
It could also offer patients and their attorneys evidence during litigation that malpractice took place—or, conversely, offer
providers evidence that it did not. Metadata trails can alert organizations that staff have been accessing patient records they
are not authorized to view, which could in turn be an effective
deterrent against snooping.
ONC’s advance notice proposes three categories of metadata,
which include recommendations from the Health IT Standards
Committee’s Metadata Power Team: patient identity, provenance, and privacy.
Patient identity metadata are used to select a particular patient from a population. The proposed standard would require:
ONC sought comments on whether additional elements are
needed for patient identity categories or if any of the listed elements should be removed. ONC also sought input on what to do