Development of an enterprise-wide clinical data repository: merging multiple legacy databases.

We describe the development of a clinical data repository whose core consists of four years of inpatient administrative and billing data from the mainframe legacy systems of the University of Virginia Health System (UVAHS). To these data we have linked a cardiac surgery clinical database and our physician billing data (inpatient and outpatient). Other databases will be merged in the future. A relational database management system (Sybase) running on a dedicated IBM RS/6000 minicomputer was employed to assemble 2.5 Gigabytes of core data describing approximately 100,000 hospital admissions over the four year period. To enable convenient data queries, the system has been equipped with a custom-built WWW user interface, which generates Structured Query Language (SQL) automatically. We illustrate the rapid reporting capabilities of the resulting system with reference to patients undergoing coronary artery bypass graft surgery (CABG). We conclude that this information system: a) constitutes a convenient and low-cost method to increase data availability across the UVAHS; b) provides clinicians with a tool for surveillance of patient care and outcomes; c) forms the core of a comprehensive database from which clinical research may proceed; d) provides a flexible interface empowering a wide variety of clinical departments to share and enrich their own clinical data.