Workflow and standards

Purpose With this presentation we want to share initial experiences in deploying IHE integration profiles, primarily XDS (Cross-Enterprise Document Sharing) and XCA (Cross Community Access). This is part of a national project in Belgium that aims at making medical history of a patient available to any physician who is currently in contact with that patient, regardless of which institution that information was collected in. In this project the medical documents typically remain at the source (for example a hospital) but there is a system that allows to find out which documents are available and to retrieve them. That system is implemented on two levels: regional partnerships between health care providers maintain an index of documents available within that hub, while a national metahub manages information about which hubs have any data on a specific patient. Our hub will group around 20 hospitals throughout the Flanders region. That national system is being developed around a Belgian standard for medical communication, as that standard was already used in a number of local initiatives. In our hub, in contrast, we have decided to use IHE profiles. We therefore must build bridges between the local standard and IHE and match the concepts in IHE to the policies in the national project. More in general, we study possibilities to advance the use of IHE in a gradual fashion. Methods Document sharing within the hub is in principle based on the XDS profile. In practice, however, current information systems in the connecting hospitals do not provide an XDS interface. At the same time we believe that the largest bottleneck in this project is exactly the effort required to connect such local information systems. Commercial software has been identified that enables those systems to connect using HL7 feeds. This solves some of the connectivity problems but not all. Already in the local setting, connecting medical information systems is more involved than just sending HL7; in an organization that extends beyond the own institution, complexity is even much higher. For example, at the time at which the information is generated the global (national) patient ID may not yet be known, or the patient may not yet have provided consent for data sharing. Handling such exceptions could be rather difficult (e.g., putting data aside and implementing an explicit trigger to transmit it later). Patient merges, which occur frequently in medical practice, can now be at the local as well as the global level. From experience in technical pilots we are now finalizing adaptations to the system that enable to concentrate most, if not all, of the complexity within the central software. The HL7 feeds from the local systems can take abstraction from these aspects, and local workflows need only be adapted in minimal ways. We did not limit ourselves to the basic XDS profile. For example, we want to provide access to previous data right after consent has been provided, but in the absence of such consent the XDS index may not yet have been populated. A lot of consideration must go to protection of personal data anyhow. We use a combination of XDS and XCA. The XCA profile was designed to exchange information between loosely coupled domains. In our project we deploy XCA for its possibilities to query information dynamically (whereas XDS assumes that the index has been populated before). This makes is possible to define a separate XDS domain for each hospital (in which even the index data is contained) while from the outside this looks as a single domain that always contains up to date information. Most importantly, this gives us more implementation options within the hub while still sticking to IHE profiles. By deploying the IHE PIX profile (Patient Identifier Cross Referencing) the local systems can keep using local patient IDs. This is particularly important for information feeds that the hospital does not want to interfere with, such as DICOM communication with a PACS. Results The system is still in technical pilot, internally as well as in connectivity to other (non IHE) hubs and the national metahub. As illustrated in Fig. 1, in the technical implementation we try to rigorously stay with IHE profiles internally, even if the environment in which this system must operate is not particularly IHE friendly. The bridge between this IHE hub and the other hubs in the Belgian project is implemented as an XCA responding and initiating gateway. For the connecting systems, and for the interactive viewing software provided over the Internet, the other hubs therefore look like IHE hubs. Current work includes integrating the national concepts for user authentication (in part based on the electronic ID card) and for secure communication, and this in such a way that we can keep using commercial components that were developed in international competition.