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SCOTTISH DIABETES CORE DATASET
ANNEX B - CLINICAL CODING IN THE NHS
Currently in Scotland, there are two main 'coding systems' - Read V2, used by GPs in Primary Care and ICD10/OPCS4 used in Secondary Care for recording information on diagnoses and procedures, mainly for central returns.
Read Version 2 - Full name is the Read Clinical Classification and it is a coded nomenclature of medical terms, designed specifically for use by clinicians in the day-to-day care of patients. They only exist as computer files, in the form of a medical thesaurus with which specially designed software can be used to look up the various terms. Version 2 evolved from an earlier
'4-byte' version and developed into a hierarchical 5-level structure, containing approximately 100,000 preferred terms and a further 150,000 synonyms which are linked to the preferred terms.
Read V2 is mapped (where possible) to ICD9, ICD10, OPCS4 and British National Formulary (BNF). The codes are maintained and developed by the English NHS Information Authority (NHSIA) in Birmingham. In addition to GPs, V2 is being used in Scotland in Child Health systems and in Law Hospital.
Clinical Terms (Read V3/CTV3) - Version 3 was developed when it was realised that V2 could not be expanded enough to take into account the requirements of the different specialties of secondary care. In 1995, consultants in various specialties, nurses, PAMs and midwives were consulted (in Working Groups) to produce lists of appropriate terms which were designed to provide greater specialist detail and to encompass the wider domain of healthcare. The resulting thesaurus of clinical terms was much larger and had a much more complex structure than V2. It is currently used in many specialised systems (mainly in England) for recording clinical data about patients on a routine basis.
SNOMED-CT - In 1999, the NHSIA, joined together with the College of American Pathologists which produces SNOMED to develop a new clinical terminology, - a merger of the best features of SNOMED and CTV3, called SNOMED-Clinical Terms (SNOMED-CT). The first release is now undergoing formal evaluation and developers are beginning to consider implementation in supporting software applications. During the development period, support for V2 codes will be phased out. Migration for users of existing terminologies will require careful planning.
It is envisaged that SCT will be pervasive in all care settings across the UK over the next 5 to 8 years. Use of a common terminology will facilitate integration of clinical information into Electronic Health Records and improve appropriate sharing of clinical information. It describes all aspects of care, i.e. not just diagnoses and procedures.
ICD10 - The International Classification of Diseases and Related Health Problems is published by the World Health Organization and is used for epidemiological and research purposes internationally. It is a classification which groups like-diseases together into meaningful categories. A new version is published approximately every 15 years. Diagnostic information collected for in-patient and out-patient episodes throughout the U.K. is coded to this classification by trained clinical coders. This information, although used locally for planning and management, is also submitted to ISD to allow national data to be collected, analysed and published for research, planning and epidemiological purposes.
OPCS4 - The Classification of Surgical Operations and Procedures was until recently maintained by the Office of Population and Census, which has now been taken over by the National Statistics Office. This classification is used mainly in the UK for grouping together like-operations and procedures to allow comparative data to be collected. The current version was published in 1990 and as yet, there has been no action to update it, despite its failure to keep up with modern surgical techniques. As with ICD, patients treated at Secondary Care level have their operations and procedures coded to OPCS and the information is then submitted centrally to ISD.
Definitions
There are three distinct processes in information handling:
Terming - for recording patient care
Encoding - for statistics and management
Grouping - for costing and other analysis.
Currently, each of the processes require different systems or 'languages', i.e. Read codes for terming, ICD/OPCS classifications for encoding and Healthcare Resource Groups/Diagnostic Resource Groups (HRGs/DRGs) for grouping. In due course, it is envisaged that SCT would be the common 'language' able to fulfil all of these roles when implemented in supporting systems.
'
Terminology' is used in the sense of a body of specialised words relating to a particular subject. A
'Standardised Terminology' is a terminology comprising specialised words which its users have agreed are appropriate names for the concepts within their subject. Usually the terms will be arranged in hierarchy or hierarchies which represent current clinical opinion concerning for example, the relationships of diseases to one another, in respect of the system involved and the type of pathology. Where several terms can correctly be used to describe a given concept, all of these may be included and linked as synonyms. A
'Standardised Coded Terminology' is a standardised terminology in which alphanumeric (usually) ciphers have been attached to the agreed terms to assist with organisation, storage, transmission and analysis. The process of selecting a term from a Standardised Coded Terminology to describe a clinical concept is described as
'Terming'. Inserting the attached code into a Clinical Information System is 'Coding'. These are
two logically distinct activities, although in an automated system, the act of selecting a term may result in a code being automatically stored in a defined field. A clinical terminology can represent clinical information on all aspects of care including symptoms, signs, investigations, diagnoses, social care, etc.
A
'Classification' is the systematic arrangement of concepts such as diseases or drugs into categories according to shared characteristics. Each category is identified by a name or
'Rubric'. The Rubrics may have codes attached for the same reasons as with the terms described earlier. Allocating a concept to a category is
'Classifying'. Inserting the attached code into an information system is
'Coding'.
A
'Grouping system' is a type of classification with highly aggregated categories to which episodes of care may be assigned according to several attributes which have already been classified, such as operation, co-morbidity and age. Allocating a unit of care to a group is called
'Grouping'.
Further Information
For further information about the clinical coding in the NHS contact:
Mrs Kate Harley,
Head,
Data Intelligence Group,
ISD Scotland,
Trinity Park House,
Edinburgh
EH5 3SE
(email:
Kate.Harley@isd.csa.scot.nhs.uk).
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