Patient identification for computer data linkage.

To permit linkage of computerized patient data obtained from different sources, a universal and efficient method of patient identification is necessary. A coding system of 16 characters with a high degree of discrimination is proposed. The first five characters code the individual's family name, the next four his given name; the next six digits are his date of birth expressed in day, month and year; and the last character codes his sex. This system, using readily available patient information, is simple to manipulate and generates codes that are also medically informative. When this method of identification was tested on a list of 18,000 persons, no identical codes were found.