Cross-enterprise, intersectoral communication often involves data exchange scenarios specified by the recipients, for example concerning subjects like infection protection and cancer registries. The vocabularies to be used are defined in the form of code lists or tables. Manufacturers of healthcare information systems usually have little influence over them, and James Cimino’s desiderata  are almost completely disregarded.
A thorough understanding of how to handle coded information is essential. It is not enough to look at codes as simple lists and manage them as such. The following issues must be kept in mind:
- How is the code list generated? Is it fully specified (“extensional”), or can it be derived according to a system of rules (“intensional”)?
- Can terms be added to the code at will (“open”) or not (“closed”)?
- Is the use of the code list mandatory (“required”) or only recommended (“suggested”)?
- At what point is the code list bound to the relevant data element (“design-time binding” vs. “run-time binding”)?
- Can the codes change over time (“dynamic”), or are they unchangeable (“static”)?
Interoperability based on IHE
Interoperability between different applications can only be advanced through appropriate use cases. Regardless of whether they involve electronic health records (EGAs), patient records (EPAs), case records (EFAs), or personal cross-enterprise patient records (PEPAs), the use of records systems represents an adequate use case for communication both within and across facilities. These records systems have a high level of acceptance because the parties involved see an immediate benefit from direct access to treatment-relevant documents.
To achieve this goal, IHE developed the integration profile “Cross-Enterprise Document Sharing”—better known as XDS—some years ago based on ebXML. On the basis of this profile, documents in any data format can be archived in a central location so that authorized users can access them efficiently. To be used efficiently, the system must give users the option of searching a record for specific documents without having to look at each one individually, or even download them.
The problem: Not every document format allows for the inclusion of descriptive attributes. Sometimes the format itself does not allow it, or changes are not permitted. The result: Metadata describing the various characteristics of a document has to be attached to it “from the outside.” In that case the metadata consists either of specific values for a particular document, e.g. “discharge letter from Dr. Meier” (title), patient “4711” (patient ID), and “created 1/7/2017” (date created), or of a selection of codes, such as “DE” (“German”) for the language.
Recommendations from IHE Germany
To standardize the metadata, a working group at IHE Germany reviewed and merged existing code lists. The value sets compiled in this way went through an official reconciliation process in the summer of 2016.
The following value sets have been compiled to date:
- Document class (DocumentEntry.classCode)
- Document type (DocumentEntry.typeCode)
- Facility type (DocumentEntry.healthcareFacilityTypeCode)
- Specialization (DocumentEntry.practiceSettingCode)
- Document format (DocumentEntry.formatCode)
- Document language (DocumentEntry.languageCode)
- Folder classification (Folder.codeList)
The value sets are now freely accessible in ART-DECOR , so they can be processed electronically by applications. An IHE guideline  contains further information on the subject generally as well as deployment. The final first edition of the guideline is now available for download; it can be regarded as a national recommendation, as the value sets are not normative.
The IHE working group is currently drafting additional value sets for metadata that has yet to be considered in the recommendation, e.g. the document’s confidentiality status (DocumentEntry.confidentialityCode), the healthcare services for which the document was created (DocumentEntry.eventCode-List), the author’s role (DocumentEntry.authorRole), the author’s specialization (DocumentEntry.authorSpeciality), and the event leading to the exchange of the document or documents (SubmissionSet.contentTypeCode).
Concerns at IHE Europe
At the European level, the question arises of how metadata is handled in XDS in individual projects. Therefore, IHE Europe has also formed a working group to collect information on deployments and derive best practices from it. However, the early feedback indicates that shared value sets are probably not practicable owing to the highly variable, nationally oriented XDS guidelines.
Assistance from XDS users from the various projects in Germany is absolutely necessary so that the recommendations developed by the working group can gain a foothold and undergo further development. IHE Germany is particularly interested in receiving modification requests and feedback, and welcomes anyone with an interest in the working group. Anyone who wants to help is invited!
Contact address: firstname.lastname@example.org.
 James J. Cimino: Desiderata for controlled vocabularies in the Twenty-First Century, http://www.ncbi.nlm.nih.gov/pubmed/9865037
 Value Sets in ART-DECOR: https://art-decor.org/art-decor/decor-valuesets–ihede-
 Leitfaden für Value Sets: http://wiki.hl7.de/index.php?title=IG:Value_Sets_f%C3%BCr_XDS