The conflict between relational databases and the hierarchical structure of clinical trials data

Relational database software has become popular for the management of certain types of commercial data. Its use is being given serious consideration in the management of data from clinical trials. Relational systems have a number of advantages over hierarchical or network systems for some types of data. However, as illustrated by an example, the data from clinical trials typically have an inherent hierarchical structure. The incorporation of hierarchically structured data into a relational database raises difficult problems of data integrity versus the complexity of the database structure. These problems, together with the long execution times of many relational operations, indicate that relational systems are not necessarily well suited for clinical trials data management.