Résumé :
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[BDSP. Notice produite par INIST sR0xKwZI. Diffusion soumise à autorisation]. Aim : The purpose of this study is to evaluate the encryption and record linkage procedure implemented by the Belgian National Cancer Registry (NCR). Methods : In order to conform to the privacy legislation, an encryption procedure has been developed for the exchange of cancer notifications between data sources and the NCR. This procedure consists of two steps. 1) A hashing algorithm irreversibly transforms identification data at source into a unique pseudonym. 2) A reversible DES-encryption of the pseudonym is performed at the NCR. Record linkage according to the pseudonym has been evaluated with 43.990 records from 16 sources. False negative and false positive matches were estimated using a deterministic linkage with a concatenation variable (month and year of birth, sex, zipcode, initial of first name). Results : Linkage based on the pseudonym resulted in 8.936 duplicate registrations. Concatenation variable linkage detected 580 more matches. Additional use of the day of birth in the variable with visual inspection of these 580 probable matches lead to 398 false negative matches (4,3%) due to spelling mistakes in the identification data. Only 4 linked pairs of tumour records were false positive matches (0,01%) due to very common last names. Conclusions : The encryption procedure is feasible. Due to errors in personal data, record linkage based on the pseudonym leads to missed duplicates and an overestimation of cancer incidence. (...)
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