Evaluation of different database designs for integration of heterogeneous distributed Electronic Health Records

EHR (Electronic Health Records) describing the diseases and treatments of patients are normally stored in the hospital locations or regions, where they are created. However, patients may be treated in different hospitals, and, therefore, there is a need for integrating health records from different hospitals to enable any hospital to obtain a total overview of a patient´s health-history. Two different types of heterogeneity problems have to be solved in order to integrate EHR systems from different hospitals in a consistent way. The first problem is that different hospitals normally do not use a common DBMS system and therefore, the traditional ACID (Atomicity, Consistency, Isolation and Durability) properties are missing across the different hospital locations. This may cause performance, autonomy, and consistency problems. However, this problem may be solved by using so called relaxed ACID properties across the different hospitals locations [1]. The second heterogeneity problem is that there are different incompatible standards for how to make EHR registrations. There is per definition no perfect solution to the second problem if the registrations from different locations are incompatible. However, the objective of this paper is to describe and evaluate different database designs for storing more or less incompatible health records from different hospitals. This is important as a solution must be chosen before it is possible to integrate different EHR systems. The Danish government has decided that the different EHR systems in Denmark have to be integrated. We hope that the evaluations of this paper can help in making the necessary architecture decisions for both the Danish hospital authorities and hospital authorities in other countries that sooner or later have to make the same type of decisions.