[Deterministic record linkage with indirect identifiers: data of the Berlin Myocardial Infarction Registry and the AOK Nordost for patients with myocardial infarction].

AIM OF THE STUDY: How can 2 pseudonymised data sets be linked? Using the example of data from the Berlin Myocardial Infarction Registry and from a German sickness fund (AOK Nordost) we will demonstrate how record linkage can be achieved without personal identifiers.
METHODS: In different steps the method of deterministic record linkage with indirect identifiers: age, sex, hospital admission date and time, will be explained.
RESULTS: We were able to show that 80.6% of the expected maximum number of patients were matched with our approach. As a result we had no duplicate matches in the linkage process, where one AOK patient was linked to 2 or more BMIR patients or vice versa. The matching variables produced enough uniqueness to be used as indirect patient identifiers.
CONCLUSION: Deterministic record linkage with the following indirect indicators: age, sex, hospital admission date and time was possible in our study of patients with myocardial infarction in a circumscribed geographical region, which limited the number of cases and avoided mismatches. © Georg Thieme Verlag KG Stuttgart · New York.