Introduction WHO Collaborating Centres for Classification ...

1 IContents WHO Collaborating Centres for Classification of Report of the International Conference for the Tenth Revision of the International Classification of List of three-character Tabular list of inclusions and four-character subcategories I Certain infectious and parasitic diseases ..I-1 II II-1 III Diseases of the blood and blood-forming organs and certain disorders involving the immune IV Endocrine, nutritional and metabolic diseases ..IV-1 V Mental and behavioural V-1 VI Diseases of the nervous system.

2 VI-1 VII Diseases of the eye and adnexa ..VII-1 VIII Diseases of the ear and mastoid VIII-1 IX Diseases of the circulatory X Diseases of the respiratory X-1 XI Diseases of the digestive system ..XI-1 XII Diseases of the skin and subcutaneous XIII Diseases of the musculoskeletal system and connective XIII-1 XIV Diseases of the genitourinary system ..XIV-1 XV Pregnancy, childbirth and the XV-1 XVI Certain conditions originating in the perinatal XVII Congenital malformations, deformations and chromosomal XVIII Symptoms, signs and abnormal clinical and laboratory findings not elsewhere XVIII-1 XIX Injury.

3 Poisoning and certain other consequences of external XX External causes of morbidity and XX-1 ii Morphology of 1 Introduction A Classification of diseases may be defined as a system of categories to which morbid entities are assigned according to established criteria. There are many possible axes of Classification and the one selected will depend upon the use to be made of the statistics to be compiled.

4 A statistical Classification of diseases must encompass the entire range of morbid conditions within a manageable number of categories. The Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems is the latest in a series that was formalized in 1893 as the Bertillon Classification or International List of Causes of Death. A complete review of the historical background to the Classification is given in Part 2a Instruction Manual (NCHS). 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.

5 In the updated Classification , conditions have been grouped in a way that was felt to be most suitable for general epidemiological purposes and the evaluation of health care. Work on the Tenth Revision of the ICD started in September 1983 when a Preparatory Meeting on ICD-10 was convened in Geneva. The programme of work was guided by regular meetings of Heads of WHO Collaborating Centres for Classification of Diseases. Policy guidance was provided by a number of special meetings including those of the Expert Committee on the International Classification of disease - Tenth Revision, held in 1984 and 1987.

6 In addition to the technical contributions provided by many specialist groups and individual experts, a large number of comments and suggestions were received from WHO Member States and Regional Offices as a result of the global circulation of draft proposals for revision in 1984 and 1986. From the comments received, it was clear that many users wished the ICD to encompass types of data other than the "diagnostic information" (in the broadest sense of the term) that it has always covered. In order to accommodate the perceived needs of these users, the concept arose of a "family" of classifications centred on the traditional ICD with its familiar form and structure.

7 The ICD itself would thus meet the requirement for diagnostic information for general purposes, while a variety of other classifications would be used in conjunction with it and would deal either with different approaches to the same information or with different information (notably medical and surgical procedures and disablement). INTERNATIONAL Classification OF DISEASES 2 Following suggestions at the time of development of the Ninth Revision of the Classification that a different basic structure might better serve the needs of the many and varied users, several alternative models were evaluated.

8 It became clear, however, that the traditional single-variable-axis design of the Classification , and other aspects of its structure that gave emphasis to conditions that were frequent, costly or otherwise of public health importance, had withstood the test of time and that many users would be unhappy with any of the models that had been proposed as a possible replacement. Consequently, as study of the Tenth Revision will show, the traditional ICD structure has been retained but an alphanumeric coding scheme replaces the previous numeric one.

9 This provides a larger coding frame and leaves room for future revision without disruption of the numbering system, as has occurred at previous revisions. In order to make optimum use of the available space, certain disorders of the immune mechanism are included with diseases of the blood and blood-forming organs (Chapter III). New chapters have been created for diseases of the eye and adnexa and diseases of the ear and mastoid process. The former supplementary classifications of external causes and of factors influencing health status and contact with health services now form part of the main Classification .

10 The dagger and asterisk system of dual Classification for certain diagnostic statements, introduced in the Ninth Revision, has been retained and extended, with the asterisk axis being contained in homogeneous categories at the three-character level. Content of the three volumes of ICD-10 The presentation of the Classification has been changed and there are now three volumes: Volume 1. Tabular List. This contains the Report of the International Conference for the Tenth Revision, the Classification itself 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.