HL7 and HCLS

The Semantic Web Health Care and Life Sciences (HCLS) Interest Group has been a driving force behind a number of interesting Semantic Web-related ventures within the clinical and biological domains, including the Translational Medicine Ontology and the Semantic Web Applications in Neuroscience (SWAN) and Neurocommons projects.

Each of these ventures rested on use of RDF or OWL to contribute in valuable ways to information exchange and integration in medical care and biological research. The initiatives formed a valuable supplement to the more general work of the W3C in supporting standards in the area of Semantic Technology, and the published results of these efforts shared the same standards of clarity and consistency as are characteristic of W3C-supported efforts in general. Their documentation has been carefully vetted by both domain experts and by those with expertise in logical model theory and in its application in Semantic Technology.

Recently, however, HCLS has taken a strange turn, which is illustrated here:

http://www.w3.org/wiki/HCLS/ClinicalObservationsInteroperability

Some samples, selected at random (punctuation and syntax as in the original):

1. From http://www.w3.org/wiki/HCLS/ClinicalObservationsInteroperability/TermInfo

Structured clinical data is often viewed as being distributed between two "domains" (also called "views," "perspectives," "layers," "components," etc.) For the purposes of this discussion, we refer to those two "component parts of a fully-formed semantic utterance of clinical data" through by visualizing them as being distributed between two models: an Information Model and a Terminology Model. Note that the term "model" is used rather specifically in the context of this discussion for the purposes of building a concrete example, the terms Information Model and Terminology Model refer to specific, well-defined model, i.e. the HL7 RIM and the SNOMED-CT models. However the concepts of Information Model and Terminology Model in the larger discussion of the full representation of a fully-formed semantic utterance need not be restricted to a single Information Model or single Terminology Model. The critical feature about the separation of the two components is that each contains its own semantics, i.e. its own concepts, relationships, etc. In general, the Information Model expresses a network of generic concepts such roles, actions, observations and their inter-relationships, etc. -- this collection of information (small"i") is also often referred to as "meta-data" or "contextual knowledge." In contrast, the information (small "i") represented by the concepts, relationships, etc. in theTerminology Model provides specific "instance-level" descriptions of higher-order constructs. It is often heavily reliant on "is-a" and "a-part-of" relationships between concepts, and is sometimes referred to as the "data layer" or "definitional knowledge model." This is the conceptual view of the world, a view in which the Information and Terminology Models provide complementary semantics and therefore at least implicitly are clearly, cleanly, and consistently related to each other via some sort of "binding interface.

2. From http://www.w3.org/wiki/HCLS/ClinicalObservationsInteroperability/HL7_RIM

OWL distinguish two kinds of properties -- object and data type properties. Their domain is always a class. The range of an object property is a class, while the range of data type properties is a data type. For example, in RIM class figure above the classCode attribute within the Entity class has a type CS class. Additionally, the classCode attribute has a range constraint restricting it to contain only one value from the CS type (CS here represents a set of code described in the RIM vocabulary domain). There are two design options to represent the classCode attribute as an OWL object property. The first option can use the restriction feature of the OWL language:

Class: Entity

SubClassOf:

entity.classCode max 1 CS, entity.classCode min 1 CS

In this case restriction is applied on the Entity class. Please note that in addition to this restriction definition, first the classCode needs to described as an object property with a domain: Entity class and Range: CS class. For the second option, thanks to OWL 2 for allowing restrictions (i.e., minimum and maximum cardinality) on properties definition as below[.]

HL7 and HCLS are both volunteer efforts comprising people with good intentions who wish to advance the use and sophistication of information technology in clinical domains. When HL7 representatives volunteered to contribute to the work of HCLS they were, accordingly, warmly greeted – not least given the fact that the HL7 community has been for some time itself talking of its standards as contributing to what they called 'semantic interoperability'.

For W3C talk of the ‘semantic interoperability’ of independent information systems signifies that these systems are able to exchange, correctly interpret, reuse and aggregate data. This is achieved by formalizing information to be exchanged using semantically well-defined languages such as RDF or OWL. "Semantics" here refers to traditional, model-theoretic semantics, as originally conceived by Alfred Tarski, and as utilized in ‘semantic technology’ for instance here. (For background see here. It is on this basis that the inferential and computational properties of OWL are defined -- just those properties which are widely held to lend significance to the work of W3C within the framework of HCLS and similar initiatives.)

For HL7, in contrast, 'semantic interoperability' is something that is to be achieved by having multiple IT systems use (or be mapped) to a common reference information model called HL7 RIM. Several groups have attempted to create ontological representations of the RIM, but – for reasons discussed extensively on this blog – such attempts have failed, because the RIM has no consistent documentation.