Health Care and the Semantic Web

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“Information consumes the attention of its recipients. Hence a wealth of information creates a poverty of attention, and a need to allocate that attention efficiently among the overabundance of information sources that might consume it.” – Dr. Herbert A. Simon, Nobel laureate, Economics, 1978.

The quote from Dr. Simon above simultaneously and accurately describes the state of the World Wide Web today – a collection of narratives - and an argument for the organizing the web into a distributed knowledge base as it was meant to be by its original creator Tim Berners-Lee.

Semantic Net

The semantic net is an old Artificial Intelligence (AI) concept. The idea behind semantic nets is that meanings of concepts are derived by their relationship to other concepts. In a graphical representation of a semantic net, concepts would constitute the nodes while being connected by lines (relationships) to other nodes or concepts. This essentially is the definition of a knowledge base, unrelated facts or information linked to arrive at knowledge.

Definition - Semantic Web

The semantic web is an evolution of the current web. The web of today is largely made up of information that is understandable by humans. The semantic web entails the addition of another layer of information that is unambiguous to machines (computers) in order to link disparate pieces information into a useful knowledge base (i.e. semantic net).


The additional machine processable layer that is a requirement of the semantic web is nothing but metadata. Previous avatars of metadata on the web are the META flags used in HTML documents and PICS (Platform for Internet Content Selection) used primarily to describe and rate adult web sites. In 1999, the W3C combined these approaches into a single effort and called it Resource Description Framework (RDF).

Resource Description Framework (RDF)

RDF uses the XML syntax for exchange of metadata over the web. In addition to transporting metadata across the web RDF also enforces rules about the use of metadata keywords in order remove ambiguity. This is done by linking a concept referred to in a web site to another concept (semantic net) thereby providing meaning (semantics).

Basically, RDF is a XML file that helps in validation. Unlike the XML schema which explains to a machine what a document should look like, RDF explains to a machine the meaning of that document through the use of a semantic net.

Semantic Web - Applications in Health Care

1.MedCIRCLE – The circle in MedCIRCLE stands for Collaboration for Internet Rating, Certification, Labeling, and Evaluation of Health Information). An effort to manage the quality of health information on the web.

2.Clinical Knowledge Management, Partners Healthcare Systems – An effort to exploit the vast amount of knowledge stored in clinical systems across the organization.

3.Active Semantic EMR – Active Semantic Documents (ASD) used to reduce medical errors and improve efficiency.


1.Lewis D, Eysenbach G, Kukafka R, Stavri ZP, Jimison H. Consumer Health Informatics: Informing Consumers and Informing Health Care. New York: Springer, 2005.

2.W3C, Health and Life Sciences SIG -

3. MedCircle -

4. Partners Clinical Knowledge Management -

5. Active Semantic EMR -

6. Semantic Web Portal -

7. Tim Berners-Lee, Scientific American -

Rajiv Haravu 00:27, 29 May 2006 (CDT)