WHY CENTRALIZED DATA BANKS WON’T WORK FOR HEALTH INFORMATION EXCHANGE (A Lightweight Approach to Implementing a Federated Model for HIE) Rex E. Gantenbein PhD, IEEE Senior Member Center for Rural Health Research and Education, University of Wyoming Federated storage In a federated model of storage, local information is stored on local servers and shared only when there is a need to exchange that information. This avoids many of the issues with centralized storage, particularly in the areas of cost, reliability, and security. However, for a fully federated model to be useful, a common, standardized format to and from which information from the local systems can be translated is required. Such standards have been proposed, but not all EHR systems necessarily adhere to them. Our research group at the University of Wyoming has developed a lightweight approach to implementing a federated model. We use Extensible Markup Language (XML) constructs to provide a Web-based interface among different information systems. We then use Web services to transport data from platform to platform. Each platform describes its interface in an XML document that resides on a network-accessible server; this platform receives messages from other platforms as requests for information, which are formatted by the requester as described by the receiver’s XML document. The platform accepts these messages and processes the requests according to its local protocol and returns the requested information via another message. Achieving interoperability This particular approach requires two interfaces to the network for each platform, one for requests and another for responses. Furthermore, when a new entity joins the network, all participating platforms need to have their interfaces modified to accept from, and send messages to, that new platform. A way to address this problem is to adopt a hybrid federated approach, which still stores data locally but includes a centralized information management system that receives messages from the platforms and routes them to the appropriate destination. In this way, only the centralized system needs to be aware of new entities. The centralized system would not contain any patient data, so it would not be an especially tempting target for hackers. However, the system could contain a basic patient registry, updated from each of the participating platforms, that would allow a specific individual to be identified anywhere within the system without the need for a system-wide unique identifier. Background Interoperability among different electronic health records (EHRs) is a critical component in implementing the exchange of health information among organizations. Non-standardized terminology and different representations of data in an EHR make the translation of the data from one format to another difficult. As a result, the use of a centralized data bank to store EHRs for multiple facilities has been proposed. Unfortunately, storing health information in a centralized location is expensive and requires all participating facilities to use the same EHR and to agree upon a unique patient identification scheme. Security and reliability are concerns, in that a large data bank would be a tempting target for unauthorized access. In addition, using a centralized data bank that only encompassed a single region (a state, for example) would still require an interface to the data banks of other regions in order to exchange information across their borders. For more information, contact Rex Gantenbein,