Table 2 Identifier cleaning
From: An efficient record linkage scheme using graphical analysis for identifier error detection
| All fields | Fields converted to uppercase blanks (e.g. whitespace) deleted | All fields |
|---|---|---|
| Forename & Surname |
remove of forenames containing baby/infant/twins, or synonyms. Remove all symbols, e.g. '. deletion of records matching internal hospital test individuals. removal of non-alphabetic values remove values containing only one letter reverse forename and surname if stated forename does not exist in any patient administration records as a forename | Forename & Surname |
| Sex | Remove unless M, F, U characters, representing male, female or unknown, respectively | Sex |
| Hospital numbers |
Remove checkdigits Remove out-of-range numeric values Deleted, along with all other identifiers, if the patient is from a Genito Urinary medicine clinic, or from the Occupational Health Department. | Hospital numbers |
| NHS numbers |
Delete out-of-range values Delete values not conforming to checkdigit requirement as described: http://www.datadictionary.nhs.uk/data_dictionary/attributes/n/nhs_number_de.asp | NHS numbers |
| Birthdate & Deathdate |
Conversion to SQL date format remove dates before 1860-01-01 remove dates in the future | Birthdate & Deathdate |