[ Changed 11th June 1998 ]
The Xtrend project involves collecting drug prescription (and collection) data from pharmacies and creating a database that supports evaluation of general practitioners' (GPs') prescription trends by district. The data is collected without patient identity information, but GPs' identity has to be protected carefully by subsequent processing - only some GPs have consented to their identity being known to data users (usually drug wholesalers or manufacturers) and the identity of the others has to be concealed.
The talk will analyse the problems in protecting the identity of the non-consenting GPs. The solution involves measures like setting a minimal number of participating GPs, practices and pharmacies in a district, and concealing the telltale signs of GPs moving between practices or going on holiday. Another interesting issue concerns the fact that the system is currently being built and this provides a certain level of `noise' against malicious data analysis. However, the situation once the system stabilises will almost certainly be different.