Coding and Nomenclatures: A Snapshot From Around the World

by R.G. Wilson, B.Sc., and I.N. Purves, MBBS, MRCGP

"Classification is a key to knowledge and an international classification makes for comparability between items of new knowledge arising out of work in new environments." Dr. M.K. Rajakumar, President of WONCA (World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians) (1).

Coded nomenclatures enable clinicians to record medical records in natural language. They are the route to added value from computerized medical record systems in that they enable computerized manipulation of data into clinical information. They also unlock the power of classification in real time via mappings. Dr. Ian Purves,Director of the Sowerby Unit for Primary Care Informatics, University of Newcastle, Newcastle-Upon-Tyne, United Kingdom.


This paper describes a preparatory phase of the American Medical Informatics Association Family Practice Primary Care Working Group's Standards in Primary Care Conference in New Orleans in 1995: an attempt to gather information using the Internet as the primary research tool. The initial phase was carried out from October to December 1995 and results continue to be gathered at the Sowerby Unit Web site:

The survey findings demonstrate the diversity of coding and nomenclature systems around the world and the variations within those systems, especially the International Classification of Primary Care (ICPC). This is partly a reflection of the marked differences among countries in the provision of health care and the resulting differences in information requirements. The consequences for the comparability of statistics derived from these coding systems are evident.


We employed a snowball sampling method using E-mail. We searched the GP-UK, Family-L, and Fam-Med LISTSERV®; approximately 70 personal contacts; and the WWW for other possible respondents. Additionally, all mailshots were prefaced with an introduction and a request to forward the survey to relevant individuals. This means we cannot be sure how many individuals eventually saw our questionnaire, although we estimate that we reached over 2,000 people. The first mailshot was sent four times due to a bug in an E-mail package, so some individuals received the survey as many as 14 times. How this may have affected the response rate is not clear. (However, no one could have claimed to have missed the message.) A second message was sent as a reminder, along with a list of the countries from which responses had already been received.


Overall 30 responses were received from 20 countries. Responses were heaviest from countries with relatively well developed primary care/family practice (PC/FP) systems with computers and therefore more widespread Internet facilities. Countries with the highest level of computerization in PC/FP, either by number (United States) or percentage (Iceland), are the most likely to be attempting to adopt a coherent national approach to coding—for example, the National Health Service Centre for Coding and Classification in the United Kingdom or the SNOMED (Systematized Nomenclature of Human and Veterinary Medicine) Secretariat in Canada.

The first set of surveys we received included the United States, Canada, Australia, New Zealand, and the United Kingdom. Responses from non-English-speakers were somewhat lower, partly because the LISTSERV® are largely dominated by English-speakers. Other supplementary explanations exist to explain nonresponse:

Coding and Nomenclature Systems

Figure 1 (the full image is 9K) shows the coding and nomenclature systems in use. Not all respondents from the same country gave the same response, which is evidence of the patchy nature of such information.

More than 90 percent of respondents stated that the 9th Revision of the International Classification of Diseases (ICD-9) continued to be used in their country in at least some areas of primary care. As the coding system used most often, the ICD-9 currently is the most common denominator and offers the best basis for comparisons among countries. However, its limitations in terms of PC/FP are well documented, and it was hoped that its successor, ICD-10, would be more applicable to the needs of health care. ICD-10 appears to be superseding ICD-9. Four of the countries responding already use ICD-10, one uses it in combination with ICPC, and South Africa and Iceland intend to implement it soon.

The development of coding schemes seems to be centered on three main systems: SNOMED (Canada), ICPC (The Netherlands), and the Read Codes (United Kingdom). Each system has its adherents and detractors, as well as strengths and weaknesses (described elsewhere in this summary). All of these systems are undergoing continuing development: The Dutch Thesaurus has been added to ICPC in the Netherlands, the ICPC is used in Australia, and SIN-FM is used in Canada. Read Version 3.1 is in the process of being finalized. The development of coding systems reflects the dynamism of PC/FP in some countries. Systems that received a mention in the "Other" category were Veska (Switzerland), TNM (Austria), NANDA (Iceland), CMBS and ATC (Australia), and PSK (Denmark).

ICPC was the second most popular coding system with survey respondents, although it is sometimes used in combination or competition with other systems or add-ons, such as the Dutch Thesaurus. Read was mentioned only in terms of the United Kingdom, Eire, and New Zealand, where it was more or less exclusive. In Australia, 10 classification systems are currently in use in a practitioner population that has only an estimated 5- to 20-percent computer usage but hundreds of computer suppliers.

Official Coding Body

The majority of respondents testified that their country has some form of centralized body for control over coding systems or that there were moves afoot to set one up. In some cases, there was confusion about who was to be in control. As one respondent put it:"Coding is a political issue here and you may well find that people in the public sector give different answers from those in the private sector."

Another put it even more bluntly: "I've forwarded the survey to Dr. X, but don't believe all that he says."

This is testimony to the ongoing controversy in this area. However, there continues to be recognition that standards are required. We hope that this conference will lead to an increased mutual understanding and a healthier dialogue.

The situation in some areas was harmonized. In the Netherlands, for instance, all clinicians used the ICPC in combination with the Dutch Thesaurus. Coding is led by the Department of Health in the United Kingdom, the Netherlands, and some other countries. In Norway the National Insurance Administration has made use of ICPC compulsory. As the respondent put it quite neatly: "No ICPC diagnosis, no pay!"

Computer Systems

Figure 2 (the full image is 7K) demonstrates the percentage of primary care doctors in each country who use computer systems. When interpreting this figure, it must be borne in mind that the majority of the respondents were able only to guess at the level of computer usage.

The most striking feature of the results was the variance among countries. Generally, usage was either more than 70 percent or less than 20 percent. The Icelandic respondent predicted that, under the SAGA 96 initiative to fully computerize Icelandic primary health care, 95 percent of clinicians would be computerized by February 1996, and all would be using the same computer system. The Icelandic respondent also reported: "We are implementing a new classification tool, including browser, where primary care providers can use ICPC as an index from subordinate sets of concepts or terms. This will submit proposals for new codes/concepts or terms. This will be an on-line feature. Therefore, you can E-mail your proposal instantly."

A similar level of computerization has been attained in the United Kingdom. The figure for computer usage in primary care given by survey respondents ranged from 5 percent to 95 percent. This range may reflect the problematic definition of "computerization." As two respondents observed, having a computer in the office is one thing, but if it is used only for appointments and accounts—and not for recording clinical data—the efforts of those working on coding and nomenclature systems will have been largely in vain.

The level of variance in the number of computer system suppliers was similarly marked, with Iceland having one and Australia having hundreds. Again these figures are approximations on the part of the respondents, but they indicate the different stages in the computerization process that the different countries have reached.


Although this is a very small-scale and skewed survey, both survey results and indications from the literature suggest that the countries from which responses were received tended to have fairly centralized health care systems. This is not a situation shared by all countries. Health care provision and the right to direct its operation and allocate resources are not powers that are relinquished easily. Health care represents a large part of the autonomy of devolved regions or states, both financially politically. This, we would argue, is the model for countries that have an organic model of health care, have a relatively unstructured pattern of access to care, or lack gatekeepers (2, 3).

A good example of this is Germany, where local PC/FP clinicians exist but are, to some extent, in competition with each other and with providers that other countries would regard as secondary care specialists. In contrast, the countries that are most advanced in using some form of coding or nomenclature seem to fit into a mechanistic model of health provision, which relies on the PC/FP sector to filter those receiving care and refer them to specialists when necessary. An example is the U.K. National Health Service. Probably a mechanistic and centrally organized model of health provision is more likely than the organic model to lead to attempts to record and classify on a national level, with resources allocated accordingly.

The survey shows the dearth of information about the state of coding and nomenclature systems, computer usage, and number of computer system suppliers in many countries. Also evident is the diversity in coding and nomenclature systems as countries modify systems to their own specific health care requirements.

If "comparability between items of new knowledge" is to be achieved, then agreement is needed on some standards or, perhaps more likely, standard methods of comparison.


  1. Lamberts H, Wood M, editors. ICPC International Classification of Primary Care. London: Oxford University Press; 1987.
  2. Fry J, Hoarder J. Primary care in an international context. London: Nuffield Provincial Hospitals Trust; 1994.
  3. Berma W, de Jong F, Mulder P, editors. European primary health care. Prepared for the WONCA (World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians) Congress. NIVEL & Royal College of Dutch Practitioners; 1993.

Other Works of Interest

Bernstein RM, Hollingsworth GR, Viner G. Evaluation of controlled medical terminologies for use in primary care electronic records. Discussion paper prepared for the American Medical Informatics Association Primary Care Working Group Conference, 1995 Nov 1; New Orleans.

Board of Directors of the American Medical Informatics Association. Standards for medical identifiers, codes, and messages needed to create an efficient computer-stored medical record. Journal of the American Medical Informatics Association 1994 Jan/Feb;1(1):1-7.

Campbell K, Das AK, Musen MA. A logical foundation for representation of clinical data. Journal of the American Medical Informatics Association 1994;1:218-32.

Côté RA, Rothwell DJ. The Systemized Nomenclature of Human and Veterinary Medicine: SNOMED International. Canadian Medical Informatics 1994 Nov/Dec;1(4):47-53.

Lamberts H, Wood M, Hofmans-Okkes I, editors. The International Classification of Primary Care in the European Communitywith a multi-language layer. London: Oxford University Press; 1993.

O'Neil M, Payne C, Read J. Read Codes Version 3: A user led terminology. Methods of Information in Medicine 1995;34:187-92.

Williams J. Do we need a classification for primary care? Journal of Informatics in Primary Care 1996 March;10:16-19. Accessible online at:

Wood M, Lamberts H, Meijer JS, et al. The conversion between ICPC and ICD-10: requirements for a family of classification systems for the next decade. Methods of Information in Medicine 1995;34(1/2).

Internet Resources

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