This is true for the individual doctor caring for the individual patient, as well as the health care organisation concerned with measuring outcomes and ensuring cost effective care. Furthermore it is recognised that patient-centred clinical information systems, integrated with decision support and other systems, are the key to high quality clinical information. However developing such systems has proved difficult and many problems remain. Perhaps the most pervasive and the most important of these problems is that of the clinical terminology or language that is used to represent the information.
Clinical terminologies are large, complex, and diverse.
For example the detail required in a patient's medical record which is used to support the daily care of the patient, is far greater than that needed for an epidemiological study or routine hospital statistics. Furthermore different users in different clinical settings require different but consistent views of that information. Clinical medicine is inherently large and complex and yet clean separations between medical specialities are not possible. Hence anything we do to represent the detailed record of clinical medicine will also be large and complex in one way or another. As the demand has grown for wider coverage and new uses, traditional techniques of coding and classification have proved inadequate, they tend to 'explode' in size and become unwieldy, inconsistent and unmanageable.