Critical State of Coding, Classification, and Terminologies in the UK: a Clinician's Perspective

Dr. Georg A. Brox, MIHM and Janis L Huston, PhD, MEd, RHIA

An Historical Review


The need to classify diseases and the causes of death dates back to the 17th century in the United Kingdom (UK), when John Graunt first published his weekly London Bills of Mortality in 1629. In 1769, William Cullen of Edinburgh, Scotland, then developed a disease classification which he titled Synopsis Nosologiae Methodicae. Not long after, William Farr, who was the Registrar General of England and Wales, worked to achieve better classification and uniformity of the use of medical statistics and in 1837 proposed a system that later became the basis of the first International List of Causes of Death. Following on this, in 1869, the Royal College of Physicians in London published a Nomenclature of Diseases. In 1893, Dr. Jacques Bertillon of France developed a uniform classification of deaths which was later published in 1903 as Nomenclature des Maladies. From these works, particularly from the International List of Causes of Death, came the foundation for the first version of International Classification of Death Causes (ICD-1). The eventual sixth revision of the classification included both diseases and causes of death and became known as the International Classification of Diseases, Injuries and Causes of Death in 1946. This was finally adopted by the World Health Organization (WHO) in 1948. WHO has continued to update both the mortality and morbidity classification schemes until the present version of ICD-10 which is now referred to as the International Statistical Classification of Diseases and Related Health Problems, 10th Edition.


In 1950, the UK General Register Office developed the first version of a classification scheme for coding operations and procedures for the UK, which was eventually taken over by the Office of Population Census and Surveys (OPCS). The first version contained 664 unsubdivided 3-character categories which was then revised in 1956 to add 10 more categories. By the third edition in 1975, the procedural classification contained 1426 valid codes. The current 4th edition was revised in 1987, with minor changes being made to the Tabular List and Alphabetic Index in 1990 to include surgical eponyms and a final index revision in 1993. The OPCS-4 now contains 1183 3-character categories with over 4000 valid codes. As it has not been updated for well over a decade, it is in dire need of a major overhaul, and there are currently plans for the development of a new procedural classification system in the UK called the National Intervention Classification (NIC) Project.

READ Codes/Clinical Terms (CT)

A classification system was introduced in 1983 in the UK for coding of primary care known as ICHPPC-2-Defined (International Classification of Health Problems in Primary Care-2nd Edition-Defined). This system, developed by the Classification Committee of the WONCA (World Organization of National Colleges, Academies, and Academic Associations of General Practitioners/Family Physicians) was first published by the American Hospital Association (AHA) in 1975 in collaboration with WHO and was related to ICD-8. The second edition, ICHPPC-2 published in 1979 by Oxford University Press, was related to ICD-9. The 1983 "Defined" version arrived in the UK, but since ICD was not currently being used by the NHS at that time, use was not widespread. Around that same time in 1982, Dr. James Read, a General Practitioner from Loughborough in the UK was developing a classification system for his own practice, which was not related to any other existing systems. These Read Codes developed into several versions and in 1990, he sold his coding system to the British Government, which intended to use it throughout the NHS. Versions 2 and 3 of the Read Codes are still both currently in use in the UK, even though the 3rd version, called Clinical Terms (CTV3), has been available since 1994. It is this version of the Read Codes that have been adopted in the collaborative project between the NHS and the College of American Pathologists (CAP) to develop SNOMED CT®.


In the 1960's, a need was identified for a nomenclature and classification system to be developed for pathology. In 1965, Dr. Roger Côté developed the multi-axial Standard Nomenclature of Pathology (SNOP) system for the CAP in the United States (US), which included four axes of topography, morphology, etiology, and function for classifying diseases. SNOP was revised in 1977 with the publication of SNOMED (Standard Nomenclature of Medicine) which added two axes of classification (for statistics and coding) to the original system. The system then became SNOMED (Standard Nomenclature of Medical and Veterinary Medical Terms) which was expanded to 11 axes. In 1992, Dr. Côté's system continued to develop to become SNOMED International (Version 2), then on to Version 3.5, SNOMED-RT (Research Terminology), and finally on to the most recent version which is combined with the UK Clinical Terms (CT) system to form SNOMED CT®.


In 1976, the first edition of ICD-O (Oncology) was developed from the MOTNAC (Manual of Tumor Nomenclature and Coding), a system which was published by the National Cancer Institute in 1951 and revised in 1968. By 1976, the classification was based on the ICD-9 system structure and published by WHO. A second edition was published in 1990 which extended the Neoplasms chapter (Chapter II) of ICD-10, to include topography and morphology (histology) of tumors.  

TNM Classification

The Union Internationale Contre le Cancer (UICC) (International Union Against Cancer) developed an international classification system to describe the extent of disease in cancer. The system categorizes cancer stages and progression of malignant tumors according to primary tumor (T), regional lymph nodes (N), and distant metastasis (M) . This system was developed to aid the clinician in staging tumors in order to plan treatment, to provide a prognosis, to assist in the evaluation of treatment results, and to facilitate the exchange of information.


Health Resource Groups (HRGs), similar to the DRGs (Diagnostic Related Groups) in the US, were developed in the early 1990's by Dr. Hugh Sanderson through the NHS Executive Headquarters and National Casemix Office. Governmental reforms in 1991 required a costing review of the healthcare services provided by the National Health Service in England and Wales. Dr Sanderson's work produced a grouping scheme that was derived from ICD-10 and OPCS-4 codes to determine the cost of the provision of diagnostic and treatment services, which previously had not been monitored. HRG-3 (Version 3) is the current system in use in the UK and is presently licensed by the NHS Information Authority (NHS IA). Although the NHS IA provides technical and management courses, Clinical Coders are not the intended audience.

Clinical Coding Standardization and Training in the UK

From its inception, the NHS delivered a rigid approach to public and social healthcare services. Up until the early 1990's, there was little awareness, understanding, or vision that provision of healthcare should consider management decisions based on accurate data, patient outcomes, or resource utilization to determine treatment effectiveness or cost. As a result, until resource management and case mix was highlighted with the introduction of HRGs, the quality and uniformity of coding of clinical data was not deemed as an important part of healthcare. Uniform training of clinical coders in the UK did not exist until the latter half of the decade and even then, the approach was haphazard. A standard qualification pathway has only recently been developed with an aim to finally raise the level of coding quality in the NHS. The NHS IA has only recently developed some standardized training materials and presently delivers courses on a limited basis to Clinical Coders. To date, there is no required curriculum as a prerequisite to sit for the ACC (Accredited Clinical Coder) assessment, but there are short workshops on offer throughout the year that are recommended prior to sitting for the examination. The main course suggested to be completed is the Basic Clinical Coding Foundation Course which only recently has been expanded to just a 14-day workshop, which still lacks adequate preparation for an acceptable level of medical terminology and anatomy/physiology background. The Course provides less than two days to focus on these two important areas of coding, so there is still a long way to go to meet the criteria for quality coding that is standard in programs elsewhere, such as in Australia, Canada, and the US. Nevertheless, this approach to training, however limited, is still a good starting point.

Current Critical State of Coding from a Clinician's Perspective

From a histopathologist's point of view of the coding and classification systems described earlier, the one which provides for the best description for diagnoses based on the findings in biotic histopathology samples and post mortem findings is the SNOMED system. This is especially true since Version 2 (International) was published and, in particular, SNOMED Version 3.5. While SNOMED is currently being used in histopathology laboratories throughout the UK, there is no version control in place. Outdated and often abbreviated versions are routinely being used, though more current versions have been available up through Version 3, Version 3.5, and SNOMED-RT. Without proper version control, it has been difficult to determine just which version is actually in place, and there is a serious lack of awareness about the differences between the versions and their incompatibilities. Additionally, there appears to be no understanding of the importance of in-depth coding principles or consistency in medical terminologies. This inconsistency is further intensified by the fact that it is the histopathology specialists themselves who assign SNOMED codes or, in some cases, they delegate the coding of diseases to untrained secretarial personnel. There has been no communication with the Clinical Coders in an attempt to support cross-mapping into ICD-10 classifications.

Presently, SNOMED CT® is not being used by histopathologists in the NHS, even though the first version was released in 2002. As of April 2004, neither has there been any pilot testing of the new system. The uptake of the system in the NHS has been slow and, except for awareness tutorials and release updates, there has been no training or even development of a training plan for implementation of SNOMED CT®. This is in spite of the large amount of time and resources that have been invested in the development of this comprehensive collaboration between the UK and the US.

On the other hand, histopathologists in the UK have been more consistent in their use of the TNM Classification of Malignant Tumours (TNM) for staging malignancies. The TNM codes which appear in the format of "pTx;pNx;pMx" are being applied to all malignant diseases except for hematological and systemic malignancies. Nevertheless, this rich clinical information is not being explained to or shared with the coding staff.

For cytopathologists, there is no clinical coding scheme available for cervical screening cytopathology other than the assignment of ICD-10 codes, such as the CIN (cervical intraepithelial neoplasia) grading scheme for severity of dysplasia. While CIN I, II, and III assignments are often made on the reports, these pathology results are often delayed or not made available at all to the Clinical Coders for an accurate assignment of the ICD-10 neoplasm codes.

In cytopathology there is, however, a sorting regimen in place from the Family Service Health Authority (FSHA) which associates health information letters to patients at different levels of risk based on the cervical screening report (A,B,C,H,X) to generate recommendation letters for follow-ups or in case of suspicion of malignancy referral recommendations to colposcopy for tissue biopsy. However, again it appears that this information is not available to coders either.

As far as the implementation of the HRG-3 Grouping system, until now, there has only been patchy usage being carried out by the financial department of hospitals. Although a cross-mapping is provided to ICD-10 and OPCS-4 codes, there is little evidence that a resources requirement of healthcare could be totally based on the HRG-3 system, primarily because of the poor quality and inconsistent application of the current classification and coding systems in the UK. Until there is more focus on data quality, on adequate mandatory training of clinical coders, and mandatory use of systematized terminology such as that provided by the SNOMED CT® scheme, the planned payment by results which will hinge on the quality of coding will be substandard and misleading. There must be a bridge between clinician and coder and, at present, there is little or no communication between clinicians and coders and the financial managers in the NHS.

A Vision for the (Near) Future

Communication between clinical coders and healthcare professionals, especially the Specialist Consultants, must be established or, if already in place, must be improved. There also must be a reliable and error-free cross-mapping between ICD-10 and SNOMED CT®. An accurate cross-mapping would allow for a financial audit based on HRG-3 data alone, which would then enable the allocation of sufficient resources to areas of diseases identified through the reported ICD-10 codes.

The coded language of healthcare professionals should be SNOMED CT®, which would also encompass all clinical procedures. This would mean that the outdated and poorly indexed OPCS-4 procedural coding scheme could be phased out. The SNOMED CT® system is the only coding language which has specific "machine" identification codes which would provide an ideal foundation for the current development in the UK to launch a paperless patient record nationwide. This initiative, called the NHS Care Records Service (NCRS), intends to provide a complete care record for every NHS patient from cradle to grave including social care information as well.

More leadership by the NHSIA is needed to encourage interested clinicians and, in particular, General Practitioners to use SNOMED CT®, and it should be carried out in pilot tests across the country. This would increase the speed of acceptance and usage of SNOMED CT® and would establish ownership of the system by health professionals.

Provided that health professionals adopt SNOMED CT®, which is primarily software- based with background cross-mapping to ICD-10, the role of clinical coders will change from that of basic coding to coding auditors. To enable trained coders to audit the quality and consistency of code assignments, it will be necessary that all software-based coding systems allow for the production of audit trails of the entire coding and mapping process over a given time period. The systems should also allow "screen shots" of individual coding episodes to be selected at random across all specialities for the purpose of monitoring and assurance of quality coding.

Once seamless coding and mapping procedures based on record text recognition are established, a secure and anonymous (after assigning a unique patient identifier) exchange of patient information will be possible for expert reference or individual disclosure to patients as needed. Only then could portable mobile devices in wireless networks safely be used with respect to patient information confidence in extracting patient information on a need-to-know basis by all healthcare providers on the healthcare team.


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Source: 2004 IFHRO Congress & AHIMA Convention Proceedings, October 2004