The linkages between the database and supporting files enables the data to be easily updated.
The NSW Centre for Health Record Linkage carried out probabilistic record linkage between the two databases, with linkage proportions over 98%% [ 25], prior to providing the researchers with de-identified records for analysis.
The linkage between the two databases was done using a unique patient identifier, which permitted a very reliable correspondence of medical services data [ 31].
Table 1 summarises all the data items to be requested and those that will be used to facilitate data linkage between the three databases.
The linkage between the three databases was performed using women's 'Numero d'Assurance Maladie', which is the unique identifier for all Quebec residents (RAMQ and Med-Écho), and using mothers and babies dates of birth, first names, and family names (RAMQ and ISQ).
11 Examples of studies involving linkage between the LABKA database and other data sources are given below.
Linkage between the pharmacy database and the computer-based program developed to identify inappropriate prescriptions involved two steps.
Follow-up for mortality status upto the 31st December 2006 was performed through record linkage between the APCR database and the Australian National Death Index.
Furthermore, a linkage between the SSATG database and the Swedish in-hospital discharge register was performed to identify possible differences in co-morbidities at treatment initiation for the infliximab and the etanercept groups.
It is relevant to mention that the linkage between the two independent databases allowed the detection of all PWA who died for any reason, and not only for AIDS-related conditions, without the inconvenience of losses to follow-up that can occur in cohort studies based on a unique data source.
