Read code: Difference between revisions

Revision as of 12:38, 23 January 2019

Revision as of 11:49, 13 March 2019

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

4-Byte Read 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 Read2, or 5-Byte Read. The first release of 5-Byte Read 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 Read 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.