The traditional approach to medical terminologies: coding and classification schemes
For over one-hundred and thirty years the systematic collecting and recording of medical information has been based on the use of traditional classifications, nomenclatures, and coding schemes of various kinds. Until relatively recently such schemes were used mainly for recording causes of death and gathering minimal diagnostic information for statistical and epidemiological purposes. Despite their many limitations, schemes such as the International Classification of Diseases (ICD) have been successful in supporting the collation and comparison of national and international statistics on morbidity and mortality, and advancing our understanding of the distribution and causes of diseases. Traditionally it has been necessary for these schemes to support:
- a relatively small number of predefined summary descriptions;
- a limited range of uses;
- manual use and direct human interpretation;
- normative use in a single language and linguistic community.
- rare and controlled extensions
All traditional schemes have been developed for a specific purpose, and that purpose is built into the structure of the scheme. For example the ICD takes a pathophysiological and aetiological view of medicine and thus it classifies diseases primarily according to the organ system involved with some important exceptions such as infectious diseases, neoplasms, and causes of injury. The assumptions and medical knowledge that go into defining and classifying the terms are embedded in the structure of the scheme. For this reason such a traditional scheme is strongly goal-oriented. This makes the scheme compact and suitable for manual use by a skilled human interpreter for an appropriate task. However the goal-orientation of systems built with this scheme makes the scheme unsuitable for other purposes. For example the management of health care resources is concerned with the demands a patient suffering from a disease places on services, and not in the aetiology and pathophysiology of the disease.