Medical Terminologies

Why are standard vocabularies for Healthcare IT message structures not enough for interoperability between providers? Unless one has spent a lot of time considering the intricate problems of Healthcare IT (HIT) interoperability, the problems with the exchange of clinical messages are not easily perceived. It is not just the message formats that need to be defined, it is the actual contents of the data fields which must be interpreted properly as well.

Clinical Data is Stored in Databases as Codes

Medical data is stored with codes. Each healthcare provider, (a doctor's office or a hospital) stores the patient data in their EHR system. IT systems save space by storing codes or abbreviations. Systems evolved to code values different ways. One system might store a Blood type of O+ as a numeric value of 1935. Another system might store the text "O+". If one looks at the bits and bytes in the actual data file, the data values are not the same. Therefore, since one sends data alone, the meaning of the number 1935 is not easily understood by a person or another doctor. One has to know the sending database's terminology codes to know what 1935 meant to the sender. That requires mapping one set of codes to another so they can be translated. Once one knows that "O+" translates to 1935 and vice versa, then the data can be translated and understood. However, as mapping all possible clinical values (all blood types, all diagnoses, all drug names, all lab test names, etc.) takes years to finish and requires several teams of experts, it gets too expensive and time consuming. Hence, the need for standardized international terminologies.

Clinical Data Exchange Challenges

When exchanging data, one has to map your data elements to the data elements of the destination system. When you are sending data outside your organization or network. There is another problem inherent in mappings. That is one of the granularity of the concepts. If two systems have different granularities, that means they have established different levels of detail for similar concepts and as a consequence of that decision, the concepts will not map directly one to another. In a simple sense, one is more detailed that other.

To eliminate the need to map data, if systems use the same standardized reference terminologies, they can exchange data that is understandable. Then when you send the code 10928, the receiver already knows what that code means as both use the same reference terminologies.

Medical Terminologies and Service Oriented Architecture (SOA)

When one uses a terminology, you can create a Service Oriented Architecture terminology service to access it. Then everyone uses a common service to query the terminology. You use the service like a method. Medical Terminology differs from country to country. You can use a terminology service to ask "How do you say Rhinitis in German?" Add to this the existence of different concepts for the same word (like the term 'cold'), different languages for the same word, and one can appreciate the complexity level of the informatics problems. SNOMED CT handles all the various concepts and foreign languages.

Medical Concepts: Making Sense of Apples and Oranges

We all know the common saying about comparing apples to apples and oranges to oranges. To keep our concepts straight with medical terminology, we must compare similar concepts - apples with apples. In Healthcare IT, we have a huge variety of concepts and data fields which comprise the EHR fruit salad! The human body is complex and is subject to many diseases which need to be diagnosed and treated. Samples are tested, and drugs are prescribed. Many hundreds of thousands of concepts are involved here. So how is meaningful data exchange possible?

Care Teams Need to Exchange Data for a More Complete Patient Record

Care teams need healthcare providers to be able to send usable data to each other so private hospitals, clinics, and private practitioners can see more complete data. We as patients want to talk to our doctor's offices, testing labs, pharmacies, and insurance companies. The contents of the EHRs, lab orders, and test results must be able to be sent, understood, and processed with the meanings intact.

What is a concept?

What is a terminology concept? If you were to tell a web browser you want to search for the keyword orange, what kind of object should it look for? Do you want the color orange or do you want the fruit called orange? These are both concepts of the word 'orange', as orange is both a fruit and a color. Getting to the intended concept of 'orange' is achieving semantic understanding of the data. We have to verify that one person wants orange, as in a paint color and that person wants to eat an orange, as in the fruit. Then we know the underlying concept for the use of the word orange.

What is an Ontology?

An ontology is a way of showing the properties of a subject area and how they are related, by defining a set of terms and relational expressions that represent the entities in that subject are Wikipedia Ontologies]. Ontologies are used to create hierarchies so we can pinpoint where in the hierarchy a particular concept falls. "Medical concept representation is not an end in itself but is desirable for the capabilities it provides. There are at least three activities are made possible by a consistent representation of medical concepts:
1) the real-time exchange of medical data;
2) the exchange of decision-support programs including alerts, protocols, care pathways, and care plans;
3) the pooling of data for outcomes research, quality assurance programs, and clinical research.
One proposed model of medical concept representation, which we adopt here,5 breaks the representation model into three components: a medical vocabulary or lexicon, a semantic data model (an information model), and a knowledge base. We discuss only the first two of these components in the following paragraphs.

Components of an Ontology: Structured Medical Vocabulary

The first component, a structured medical vocabulary, is an organized set of terms or words with associated codes. Coded medical vocabularies are one of the foremost issues in the field of medical informatics. Indeed, Dr. Smith noted that a unified controlled medical vocabulary was one of the grand challenges of medical informatics. There is a large and growing set of publications related to the development and use of structured medical vocabularies.

Components of an Ontology: Semantic Data Model

The second component of medical concept representation, a semantic data model (SDM), is a description (template or data structure) of how vocabulary items can be combined to make a valid representation of medical information. Semantic Data Models have also generated a large number of publications. Often unrecognized as SDMs are the health care data exchange standards, particularly CEN TC251/PT-00822 and CEN TC251/PT-02223 of Technical Committee 251 (Health Informatics) of the European Committee for Standardization; HL7 (Health Level 7); the DICOM standards; and specifications E123829 and E139430 of the American Society for Testing and Materials (ASTM). These standards describe the interchange format and syntax for messages that can be exchanged between medical computing systems."

Case Study: Exchange of Gender Concepts Between Systems

Let's examine the challenges with exchanging data values between organizations with different missions. For example, one federal agency might send another agency the value for a data field called 'sex'. It contains not "M", "F" or "O", but the number 22. What does this mean? Well, the FBI has 23 different codes for sex, as their values include “male”, “female”, "male posing as female", "female posing as male", etc. What one expected to receive was the concept of medical gender. Really what the FBI needs is a "Sexual Appearance" concept apart from just the basic concept of medical gender. Their concepts rightly come from the job function they perform: it is their job to identify people. This is their mission. Data values come from ones mission. Healthcare providers need to treat people. Hence, hospitals use a concept called administrative gender.

Organization of Concepts into a Reference Framework of Hierarchies

How can we sort out all these concepts? SNOMED CT is a framework in which these concepts are organized in a vast carefully curated hierarchical database of over 1M entries. In here a construct is established which stores individual words properly in context. SNOMED CT is updated periodically by people who are professional medical Terminologists.The International Classification of Diseases, ICD, is another large terminology.

When one uses a terminology, you create a Service Oriented Architecture terminology service to access it. Then everyone can use a common service to query the terminology. Then you have to find out about and learn how to use the service.