Read code: Difference between revisions

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{{Short description|Medical code system used in the UK}}

'''Read codes''' are the standard [[Medical terminology|clinical terminology]] system used in [[General Practice]] in the United Kingdom. It supports detailed clinical encoding of multiple patient phenomena including: occupation; social circumstances; ethnicity and religion; clinical signs, symptoms and observations; laboratory tests and results; diagnoses; diagnostic, therapeutic or surgical procedures performed; and a variety of administrative items (e.g. whether a screening recall has been sent and by what communication modality, or whether an item of service fee has been claimed). It therefore includes but goes significantly beyond the expressivity of a [[diagnosis code|diagnosis coding]] system.

{{Use dmy dates|date=June 2019}}

'''Read codes''' are the standarda [[Medical terminology|clinical terminology]] system usedthat was in widespread use in [[General Practice]] in the United Kingdom until around 2018, when NHS England switched to using [[SNOMED CT]]. ItRead codes are still in use in Scotland and in England were permitted for use in NHS secondary care settings, such as dentistry and mental health care until 31 March 2020. Read codes supportssupport detailed clinical encoding of multiple patient phenomena including: occupation; social circumstances; ethnicity and religion; clinical signs, symptoms and observations; laboratory tests and results; diagnoses; diagnostic, therapeutic or surgical procedures performed; and a variety of administrative items (e.g. whether a screening recall has been sent and by what communication modality, or whether an item of service fee has been claimed). It therefore includes but goes significantly beyond the expressivity of a [[diagnosis code|diagnosis coding]] system.

==History==

Since its origins in the 1980s,<ref>{{cite journal|last=Benson, |first=Tim. "|title=The history of the Read codes: the inaugural James Read Memorial Lecture 2011." ''|journal=Informatics in primaryPrimary care''Care |volume=19. |issue=3 (|date=2011): 173-182|pages=173–182 |doi=10. http:14236//wwwjhi.ingentaconnectv19i3.com/content/bcs/ipc/2011/00000019/00000003/art00008811|pmid=22688227 |doi-access=free }}</ref> the system has evolved through three major technical design changes and significantly expanded its content.

===READRead version 1 (4-byte READRead)===

The first version was developed in the early 1980s by [[Dr James Read]], a Loughborough general medical practitioner.<ref name="BCS">{{cite web |vauthors=Bentley T, Price C, Brown P |title=Structural and lexical features of successive versions of the Read Codes |url=http://www.phcsg.org/main/pastconf/camb96/readcode.htm |work=The Proceedings of the 1996 Annual Conference of The Primary Health Care Specialist Group of the [[British Computer Society]] |date=13–15 September 1996 |accessdateaccess-date=2010-04-17 |url-status=dead |archive-url=https://web.archive.org/web/20100829143656/http://www.phcsg.org/main/pastconf/camb96/readcode.htm |archive-date=29 August 2010 }}</ref> The scheme was structured similarly to [[International Statistical Classification of Diseases and Related Health Problems|ICD-9]]:

* each code was composed of four consecutive characters: first character 0-9, A-Z (excepting I and O), remaining three characters 0-9, A-Z/a-z (excepting i,I,o and O) plus up to three trailing period '.' characters

* the relative position of one code to another was represented through the code itself: [J...] is the common ancestor of all other codes with 'J' as the first character, and [J1..] in turn the common ancestor of all codes beginning 'J1'.

Because of its four character code structure, READRead Codes version 1 was more commonly known as 4-Byte READRead. The first release was in April 1986; the final official release of 4-Byte READRead occurred in April 2009.

===READRead version 2 (5-byte READRead)===

4-Byte READRead could only encode a monoaxial hierarchy with a maximum of 4 hierarchical levels. The operational NHS requirement to provide a direct crossmap to both [[ICD|ICD-9-CM]] and [[OPCS|OPCS-4]] implied an additional hierarchical level was required. Accordingly, a new scheme was devised with exactly the same technical properties as 4-Byte READRead except that the code structure was extended to 5-Bytes. This became known as READ2Read2, or 5-Byte READRead. The first release of 5-Byte READRead occurred sometime prior to January 1991. The October 2010 release contained 82,967 discrete 5-byte codes (although the actual number of discrete clinical concepts that may be represented is estimated to be slightly lower - 82,593 - because of duplicate entries).

A later extension of READRead version 2 product family was the co-publication of a drug and appliance dictionary. This follows the same technical structure (5-character alphanumeric codes with first character lower case alpha organised in a monohierarchy). Released every four weeks, the October 2010 release contained 52,316 codes.

A popular misconception is that all 4-Byte codes are also present in 5-Byte, where they will also carry the same meaning. Whilst in the majority of cases any 4-Byte code of the general form 'wxyz' will be equivalent to a 5-Byte code of the form 'wxyz.', there are notable exceptions. The 4-Byte code [E333 Fear of flying], for example, corresponds to 5-Byte [E202A Fear of flying]; no [E333.] code exists in 5-Byte READRead at all.

===NHS mandationmandate===

In 1988 a joint conference of the [[Royal College of General Practitioners]] and the [[British Medical Association]] recommended standardisation of the system in general practice [[Electronic medical record|Electronic Medical Record (EMR)]] systems and the [[National Health Service]] mandated this in April 1999.<ref name="NHS-CfH">{{cite web |title=Frequently Asked Questions about Clinical Terms (The Read Codes) |url=http://www.connectingforhealth.nhs.uk/systemsandservices/data/readcodes/faqs/index_html#1 |publisher=NHS Connecting for Health |accessdateaccess-date=2010-04-17}}</ref> The intellectual property of the codes themselves was purchased outright by the UK government, and they have therefore been published under [[Crown Copyright]] ever since.

===READRead version 3 (Clinical Terms Version 3 or 'CTV3')===

A third and more radically progressive version was devised through the 1990s in an attempt to address some of the more serious technical limitations of the earlier designs, including:

* Although codes remain 5-bytes in length, the hierarchical relationship between codes is no longer represented through the codes themselves but rather through a separate table listing all binary parent-child relations; this allows for a [[polyhierarchy]] of indefinite depth.

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==Production and license==

In the 1990s the Read codes were released on a quarterly basis for clinical terms, and monthly for drugs and appliances.<ref>{{cite journal|last1=Robinson |first1=David |last2=Schulz |first2=Erich |last3=Brown |first3=Philip |last4=Price |first4=Colin |title= Updating the Read Codes. User-interactive Maintenance of a Dynamic Clinical Vocabulary |journal=Journal of the American Medical Informatics Association |volume=4 |issue=6 |date=1997 |pages=465–472 |doi=10.1136/jamia.1997.0040465|pmid=9391934 |pmc=61264 |doi-access=free }}</ref> Latterly, they were maintained by the UK Terminology Centre, a division within NHS Data Standards and Products (in turn a division of [[NHS Connecting for Health]]) and both versions were released biannually, in October and April, under the [[Open Government Licence]].<ref>{{cite web|url=https://data.gov.uk/dataset/f262aa32-9c4e-44f1-99eb-4900deada7a4/uk-read-code |title=UK Read Code |website=data.gov.uk |date=24 March 2015 |publisher=[[UK Government]] |access-date=18 March 2020}}</ref>

Both actively maintained versions of the READ codes are now maintained by the UK Terminology Centre, a division within NHS Data Standards and Products (currently in turn a division of [[NHS Connecting for Health]]).

Both versions are released biannually, in October and April, under the [[Open Government Licence]].

License application, and distribution, are now electronic only via the UKTC [https://www.uktcregistration.nss.cfh.nhs.uk Terminology Reference data Update Distribution] service.

==READRead and SNOMED==

[[SNOMED CT]] was created in 2001 out of a technical, editorial and content merger of CTV3 and [[Systematized Nomenclature of Medicine|SNOMED RT]], an American system. A significant part of the International Core content of SNOMED CT derives directly from CTV3; most of this content is identifiable as those SNOMED ConceptIDs where the CTV3ID column in the sct_concept table cites a code NOT beginning with the characters 'XU'.

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==Deprecation and withdrawal==

In preparation for the whole English health system moving to SNOMED CT by April 2020, [[primary care]] systems arewere to have adopted the new [[nomenclature]] by April 2018.<ref>{{cite web|title=SNOMED CT Implementation in Primary Care|url=https://digital.nhs.uk/SNOMED-CT-implementation-in-primary-care|publisher=NHS Digital|accessdateaccess-date=1 October 2017}}</ref> Secondary care, including Mental Health and Dentistry, iswas mandated to move to SNOMED by April 2020.<ref>{{cite web|title=SNOMED CT |url=https://digital.nhs.uk/snomed-ct|publisher=NHS Digital |accessdatearchive-url=https://web.archive.org/web/20171001213917/https://digital.nhs.uk/snomed-ct|archive-date=1 October 2017}}</ref>

The former Information Standards Board for Health and Social Care (ISB) set December 2010 as the deprecation date for Read version 2, but did not set a date for its withdrawal at the time.<ref>{{cite web|title=Information Standards Notice – Deprecation|url=http://www.hscic.gov.uk/media/15868/1553disn/pdf/1553disn.pdf|publisher=Standardisation Committee for Care Information|accessdateaccess-date=15 May 2015}}</ref> In August 2014 the ISB's successor, the Standardisation Committee for Care Information (SCCI), formalised the withdrawal time frame of Read version 2: A final updated release for Read version 2 is to be made available on 1 April 2016, and will be withdrawn completely on 1 April 2020.<ref name=HSCIC-Read>{{cite web|title=Deprecation of Read Version 2 and Clinical Terms Version 3|url=http://systems.hscic.gov.uk/data/uktc/readcodes|publisher=Health & Social Care Information Centre|accessdateaccess-date=15 May 2015}}</ref>

The deprecation and withdrawal time frame for Read version 3 was also agreed by the SCCI in August 2014. The deprecation date was set at 1 September 2014,<ref>{{cite web|title=Information Standards Notice – Deprecation|url=http://www.hscic.gov.uk/media/15869/1552disn/pdf/1552disn.pdf|publisher=Standardisation Committee for Care Information (SCCI)|accessdateaccess-date=15 May 2015}}</ref> with a final updated release for 1 April 2018, and complete withdrawal on 1 April 2020.<ref name=HSCIC-Read />

The Read Codes Drug and Appliance Dictionary (DAAD) was published for the final time on 1st1 April 2016, with data since being pulled from public circulation.<ref>{{cite web|title=Read Codes|url=https://digital.nhs.uk/article/1104/Read-Codes|publisher=NHS Digital|accessdateaccess-date=1 October 2017}}</ref>. The intent of [[NHS Digital]] is to migrate users to the Drugs and Medicines Dictionary (dm+d), which itself is based upon SNOMED CT.

==See also==

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==References==

{{reflist|2}}

{{Medical classification}}

[[Category:National Health Service]]

[[Category:Diagnosis classificationcodes]]

[[Category:Health standards]]

[[Category:General practice]]

[[Category:Clinical procedure classification]]