Performance of record linkage for cancer registry data linked with mammography screening data

• Published in: Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz Vol. 53; no. 7; pp. 740 - 747
• Main Authors: Giersiepen, K, Bachteler, T, Gramlich, T, Reiher, J, Schubert, B, Novopashenny, I, Schnell, R
• Format: Journal Article
• Language: German
• Published: Germany 01-07-2010
• Subjects: Breast Neoplasms - epidemiology; Breast Neoplasms - prevention & control; Diagnostic Errors; Early Detection of Cancer - standards; Early Detection of Cancer - statistics & numerical data; False Negative Reactions; Female; Germany; Humans; Mammography - standards; Mammography - statistics & numerical data; Medical Record Linkage - standards; Quality Assurance, Health Care - standards; Quality Assurance, Health Care - statistics & numerical data; Registries - standards; Registries - statistics & numerical data; Germany
• ISSN: 1437-1588
• DOI: 10.1007/s00103-010-1084-1

The evaluation of the German Mammography Screening Program requires record linkage with data from cancer registries in order to measure the number of false-negative mammograms and interval cancers. This study aims at evaluating the performance of the established linkage method based on identifiers encrypted by the standard procedure of the German cancer registries. In addition, the results are compared with an alternative method based on plain text identifiers. A total of 16,572 records from the Bremen Mammography Screening Pilot Study were linked with data from the Bremen Cancer Registry. Based on a gold standard set of matching record pairs, homonym and synonym errors were determined. Given the customary threshold value in cancer registries, the plain text method showed a lower rate of synonym errors (2.1-5.1%) and a lower rate of homonym errors (0.01-0.15%). As 10.4 million women are invited to take part biennially in screening, the corresponding figures would be 3,237 homonym errors for the standard procedure and 294 using the plain text method provided equivalent conditions. The 11-fold increase in the homonym error rate documents the trade-off for better data protection using encrypted data.