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MEDICAL CLASSIFICATION SYSTEMS
Since the introduction of clinical information systems,
clinical coding and clinical systems have acquired important roles in medical
informatics. Over the years, classification and codification systems have
evolved, not only to reduce software development, maintenance and processing
time but also to become the heart of electronic medical records (EMRs).
- Codes – are numeric or alphanumeric abbreviations
that can expand into some meaning.
- Nomenclature – An agreed system of assigned names.
- Classification – Systematic representation of terms
and concepts and the relationship between them.
- Terminology – A set of words or expressions
together with a definition used within a certain field.
Clinical classifications are useful in the areas of
decision-making and research. They usually aim to be accurate, have unambiguous
expressions and complete. In the UK, the British
Association of Clinical Terminology Specialists (BACTS) ensures the
quality of terminology development through its professional members.
The following are examples of clinical classification systems
Classification of Disease – 10 (ICD-10) – International
Classification of Disease is the oldest classification and is available
worldwide. It is maintained by the World Health
Organisation (WHO) and ICD-10 is the latest revision and came into use
in April 1994. ICD-10 differs from the previous version (ICD-9) in that it has
alphanumeric categories rather numeric categories. There is an
ICD-10 homepage at the World Health Organisation site. A clinical
modification of ICD-10 (ICD-10-CM) has been developed by the
National Centre for Health Statistics
Systematized Nomenclature of Medicine (SNOMED)
– SNOMED is a classification that is maintained by SNOMED
International, a division of the College of American Pathologists (CAP).
SNOMED’s design is based on detailed and specific nomenclature and has been
successfully implemented internationally. The National Health Service in the UK
has adopted a clinical version (SNOMED
CT) as its preferred clinical terminology.
NHS Clinical Terms (formerly
READ Clinical Classification) -
The READ Clinical Classification was designed by Dr James Read, a UK General
Practitioner, for use by clinicians to cover the deficiencies that were not
addressed by the already available codes. The UK’s National Health Service
(NHS) purchased the READ codes in 1990 and since then many clinicians have been
involved in the development of subsequent versions. The third version, which is
also the latest, has a complete structural organisation with five hierarchical
levels that takes advantage of modern day database technology. The READ
Clinical Classification is still being used in the NHS, even though the NHS
Executive has adopted SNOMED CT, as it preferred terminology.
Observation Identities, Names and Codes (LONIC) –
The LONIC database facilitates the exchange of laboratory results and the
identification of clinical observations through a set of universal identifiers.
The Regenstrief Institute maintains the LONIC database and its supporting
Medical Subject Headings (MeSH)
Thesaurus – MeSH was developed by the
National Library of Medicine (NLM) to create the INDEX MEDICUS, which
is a scientific publications directory. MeSH has two categories of headings,
which are arranged hierarchically. There are the Major MeSH headings, which are
used for the description of the primary content of journals and the MeSH
Headings, which describe the secondary content. The MeSH headings are published
in a book called Medical Subject Headings – Annoted Alphabetic List. The
headings are also used when accessing materials from the online medical journal
Unified Medical Language System
(UMLS) – the National Library of Medicine (NLM) has developed
UMLS since 1986. It has allowed healthcare professionals and researchers
retrieve and integrate information from multiple electronic biomedical sources
ranging from clinical records databases through directories of people and
organisations to knowledge-based systems. UMLS is especially useful in
overcoming multiple expressions of a single concept. The 11th
edition of UMLS contains about three quarters of a million of such concepts,
which map to MeSH, ICD-9-CM, SNOMED and other coding systems through its
Metathesaurus. The UMLS Metathesaurus is just one of the components that make
up the UMLS knowledge source. Some of the others include the Semantic Network,
which provides a network of semantic types of all concepts represented in the
Metathesaurus, and the Specialist Lexicon that contains linguistic information
about biomedical and general English terms.
North American Nursing Diagnosis Association (NANDA)
Classification – The NANDA classification is a set of nursing
diagnosis introduced by the North American Nursing Diagnosis Association
(NANDA) in 1973. According to NANDA, the classification is based on “a
selection of nursing interventions to achieve outcomes for which the nurse is