Existing Classifications and Nomenclatures

In the following sections we present some details of the most important standardised terminologies in terms of classifications, nomenclatures and thesauri.

1.1.1 The International Statistical Classification of Diseases and Related Health Problems, 10th revision — ICD10

The ICD is a classification system developed collaboratively by the World Health Organization (WHO) and ten international centers.

The Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems is the latest in a series that was formalised in 1893 as the Bertillon Classification or the International List of Causes of Death. While the title has been amended to make clearer the content and purpose and to reflect the progressive extension of the scope of the classification beyond diseases and injuries, the familiar abbreviation “ICD” has been retained. The ICD-10 was approved by the World Health Organization in 1990 and has been available for implementation since 1993.

ICD-10 classifies diseases, injuries and causes of death, as well as external causes of injury and poisoning. The classification has 21 chapters with alphanumeric categories and subcategories. ICD-10 contains about 8,000 categories that are valid causes of death. ICD-10 uses 4-digit alphanumeric codes compared with 4- digit numeric codes in ICD-9. ICD-10 has an alphanumeric format with a code size ranging from 3 to 5 characters. Valid ICD-10 disease codes include three-, four- and five-character codes e.g. R11 Nausea and vomiting, J20.6 Acute bronchitis due to rhinovirus, M08.00 Juvenile Rheumatoid Arthritis. The range of ICD-10 codes is A00.00 to Z99.99. The Morphology code range is M0000/0 to M9999/9 [14], [7]. ICD-10 is published in three volumes.

Volume 1 — Tabular List:

The first volume, which runs well over 1,000 pages, contains the classification at the three- and four-character levels, the classification of the morphology of neoplasms, special tabulation lists for mortality and morbidity, definitions and the nomenclature regulations.

Volume 2 — Instruction Manual:

The second volume consolidates notes on certification and classification formerly included in Volume 1, supplemented by a great deal of new background information, instructions and guidelines for users of the tabular list. Volume 3 — Alphabetical Index:

The final volume presents the detailed alphabetical index [24]. Overview of ICD-10 Chapters and Code Ranges [3]:

I Certain infectious and parasitic diseases (A00-B99) II Neoplasm (C00-D49)

III Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D99)

IV Endocrine, nutritional and metabolic disease (E00-E99) V Mental and behavioural disorders (F00-F99)

VI Diseases of the nervous system (G00-G99) VII Diseases of the eye and adnexa (H00-H49)

VIII Diseases of the ear and mastoid process (H50-H99) IX Diseases of the circulatory system (I00-I99)

X Diseases of the respiratory system (J00-J99) XI Diseases of the digestive system (K00-K99)

XII Diseases of the skin and subcutaneous tissue (L00-L99)

XIII Diseases of the musculoskeletal system and connective tissue (M00- M99)

XIV Diseases of the genital urinary system (N00-N99) XV Pregnancy, childbirth and the puerperium (O00-O99)

XVI Certain conditions originating in the perinatal period (P00-P99) XVII Congenital malformations, deformations and chromosomal

abnormalities (Q00-Q99)

XVIII Symptoms, signs and abnormal clinical and laboratory findings not classified elsewhere (R00-R99)

XIX Injury, poisoning and certain other consequences of external causes (S00-T99)

XXI Factors influencing health status and contact with health services (Z00- Z99)

1.1.2 ICPM International Classification of Procedures in Medicine The German ICPM (International Classification of Procedures in Medicine) is a classification of clinical procedures, describing diagnostic, surgical or other conservative procedures. The ICPM serves scientific statements, quality assurance and the representation of insurance claims and is an obliging basis of procedure documentation.

The ICPM is the German translation, adaptation and extension of the ICPM- DE (International Classification of Procedures in Medicine, Dutch Extension), based on the ICPM-WHO. The Friedrich-Wingert-Foundation is responsible for the maintenance, development and extension of the ICPM. Since 1994 Version 1.0 has been used by hospitals for routine applications of classifications. In further developments of the ICPM, the SNOMED nomenclature will be incorporated.

The main chapters of the ICPM cover: x Diagnostic procedures, x Prophylactic procedures, x Surgical procedures,

x Other therapeutic procedures, x Additional procedures.

Drugs, laboratory and radiological procedures are not included in the German version.

The concepts are arranged in a hierarchy. Each concept has a six-character alphanumeric code. The nomenclature is organized into six levels of hierarchy. The following is a sample of the six-level hierarchy:

x Chapter: e.g. 5 — surgical procedures,

x Group: e.g. 5-010 to 5-049 — surgical procedures on the nervous system,

x Category: e.g. 5-01 — incision and excision on the skull, brain and meninges,

x Subcategory: e.g. 5-010 — cranial puncture,

The groups are ordered by the type of procedure. An exception is made in the chapter “surgical procedures”. Here a topographic-anatomical order by organs and body systems is used. The German version of the ICPM is available as a book or in three different CD-ROM versions [10]. The ICPM version 2.1 (Operationenschlüssel nach Paragraph 301 Sozialgesetzbuch V (OPS-301)) provided by DIMDI — the German Institute for Medical Documentation and Information — is available online [5]. Unfortunately, in order to modify the German procedure classification OPS with respect to the needs of the German DRG-system (G-DRGs), the newer versions of the OPS and the ICPM are no longer compatible.

1.1.3 SNOMED Systematized Nomenclature of Human and Veterinary Medicine

The SNOMED Systematized Nomenclature of Human and Veterinary Medicine is a broad-based, comprehensive clinical terminology and knowledge base, developed and maintained by SNOMED International, a non-profit division of the College of American Pathologists.

SNOMED is a structured nomenclature and classification system created for indexing the entire medical record, including signs and symptoms, diagnoses and procedures. The terms are placed into natural hierarchies, each represented by a six-digit alphanumeric termcode. SNOMED International is updated annually; version 3.5, released in 1998, contains more than 150,000 terms. Additionally the ICD-9 terms and codes are incorporated, mostly along the Disease/Diagnosis axis. SNOMED International contains 11 axes:

x Topography (anatomy): A functional anatomy for human and veterinary medicine (13,165 records),

x Morphology: Terms used to name and describe structural changes in disease and abnormal development (5,898 records),

x Function: Terms used to describe the physiology and pathophysiology of disease processes (19,355 records),

x Disease/diagnosis: A classification of the recognised clinical conditions encountered in human and veterinary medicine (41,494 records),

x Procedures: A classification of healthcare procedures (30,796 records), x Occupations: Developed by, and used with permission from, the

International Labour Office in Geneva, Switzerland (1,949 records), x Living organisms: Living organisms of etiological significance in human

and animal disease (24,821 records),

x Chemicals, drugs and biological products: Including pharmaceutical manufacturers (14,859 records),

x Physical agents, forces and activities: A compilation of physical activities, physical hazards and forces of nature (1,601 records),

x Social context: Social conditions and relationships of importance to medicine (1,070 records),

x General linkage modifiers: Linkages, descriptors and qualifiers to link or modify terms from each module (1,594 records).

Of particular note is the systematised, multiaxial and controlled vocabulary. Terms in SNOMED are all arranged in a hierarchy, represented by an alphanumeric term code where each digit represents a specific location in the hierarchy. For example, T-20000 represents the respiratory system; T-28000 the lungs; and T-28010 the alveoli. Multiaxial refers to the ability of the nomenclature to express the meaning of a concept across several axes. For example Tuberculosis (D-0188) affects the lung (T-28000), is caused by M. Tuberculosis (E-2001), appears as Granuloma (M-44060) and causes Fever (F- 03003).

A controlled vocabulary allows the user to record data in the patient’s record using any one of a variety of synonyms, but references it back to a single primary concept. For example the preferred term Atopic dermatitis, NOS (D0- 10130) has the synonyms Allergic eczema, Besnier's prurigo, Atopic neurodermatitis, Allergic dermatitis, Prurigo of Besnier and disseminated neurodermatitis [13].

SNOMED International is rapidly being accepted worldwide. The American Veterinary Medical Association and the American Dental Association have adopted/endorsed SNOMED for their use. The American College of Radiology/National Equipment Manufacturers Association will be using a subset of SNOMED in their Digital Imaging Communication Standard (DICOM). SNOMED Clinical Terms will be a medical terminology resource that combines the content of SNOMED RT with the United Kingdom’s Clinical Terms Version 3 (formerly known as the Read Codes V3) [23].

1.1.4 Medical Subject Headings MeSH

The Medical Subject Headings, published by the National Library of Medicine, consists of a controlled vocabulary used for indexing articles, for cataloguing books and other holdings and for searching MeSH-indexed databases, including MEDLINE. The MeSH vocabulary is continually updated by subject specialists in various areas.

There are more than 19,000 main headings in MeSH. In addition to these headings, there are 103,500 headings called Supplementary Concept Records (formerly Supplementary Chemical Records) within a separate chemical thesaurus. There are also thousands of cross-references that assist in finding the most appropriate MeSH heading, for example, “Vitamin C - see Ascorbic Acid”. MeSH consists of a set of terms or subject headings that are arranged in both alphabetic and hierarchical structures. MeSH is a principal component vocabulary of the Unified Medical Language System (UMLS®) [15].

The Medical Subjects Heading is divided into two sections: Alphabetic List and Tree Structures. The Alphabetic List section contains the subject headings arranged in alphabetic order with cross-references. The tree structure is a list in which the subject headings are divided into categories. Most categories are further divided into subcategories, identified by an alphanumeric designation. The terms in each subcategory are arranged hierarchically, in up to seven levels, from the most general to the most specific.

MeSH Categories:

x Analytical, Diagnostic and Therapeutic Techniques and Equipment Category E,

x Anatomy Category A,

x Anthropology, Education, Sociology and Social Phenomena Category I, x Biological Sciences Category G,

x Chemicals and Drugs Category D, x Diseases Category C,

x Geographical Locations Category Z, x Healthcare Category N,

x Humanities Category K,

x Information Science Category L, x Organisms Category B,

x Persons Category M,

x Physical Sciences Category H,

x Psychiatry and Psychology Category F,

x Technology and Food and Beverages Category J [19].