Development of a computer linkage system for a blood recipient notification program in Nova Scotia.

OBJECTIVES To assess the potential uses of computer-assisted record linkage in the surveillance of infectious diseases, using the Nova Scotia blood recipient notification program as the example. METHODS We developed a computer-assisted, multiple-pass, probabilistic record linkage to link records for blood recipients identified by the Nova Scotia notification program (Nova Scotia Phase I Blood Bank File information) with corresponding Nova Scotia Health Card Registration File records to obtain current mailing addresses to contact potentially living recipients. We used variables available from both files (e.g., name, date of birth, gender, and health care registration number) to link records, after eliminating duplicates/deceased cases. RESULTS Among 23,925 eligible records in the Nova Scotia Phase I Blood Bank File (1984-1990), there were 1,818 (7.8%) duplications and 8,675 deceased cases, leaving 13,432 cases for linkage. 8,713 (65%) cases were successfully linked to the 1998 Health Card Registration Data File for current mailing addresses. INTERPRETATION Multiple-pass linkage seems acceptable for maximizing detection of correctly matched records for look-back projects. To overcome quality/lack of information obstacles, future look-back linkages should explore the use of supplementary data files (tax files, voter lists, license files, other provincial databases) to obtain most current addresses.