Syntactic interoperability. Not exactly a popular topic of conversation at most dinner parties. But it's an important concept to grasp if you're in medical informatics.

It helps if you understand the concept of syntax in the English language itself. The best way to explain syntax is by listening to someone who ignores it. Jedi Master Yoda, for instance, was famous for lines like "Truly wonderful, the mind of a child is" and "Much to learn, you still have."

XML, HTML, and other formatting languages likewise have their own structures, or syntax. XML is used to identify different pieces of information and structure that information so that it forms a meaningful document. One advantage of XML over HTML is that it serves as a set of guidelines rather than a rigid set of tags, which means you can define your own tags depending on what you need to accomplish. So if you're putting a cake receipt on the Internet, you can create separate tags for food, calories, and so on.

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HL7, which stands for Health Level Seven, is the set of standards that lets a healthcare provider format electronic information so that it can be exchanged between two or more databases that speak different languages. It allows data in a hospital's radiology information system, for instance, to be shared with the laboratory information system as well as the hospital information system that contains a patient's basic identification and admission data.

Altova, a vendor that provides various XML and database tools, explains it succinctly on its site: "An HL7 message is composed of a series of segments, each of which identifies the type of information the message contains (e.g., diagnosis, insurance, observation result). In turn, each segment includes one or more composites (or fields) that carry the actual information being conveyed (e.g., name, test value, dosage)."

Unfortunately, EMRs from one vendor don't always play nicely with EMRs from other vendors or with other hospital information management systems because they speak different languages. Some healthcare providers have tried to solve this problem with integration engines that normalize the HL7 messages so that EMRs can better understand them.

Health Story, an alliance of healthcare vendors, providers, and associations, has taken a different approach, developing implementation guides for nine clinical document types that conform to HL7's Clinical Document Architecture. The XML-based CDA documents--collectively known as the Consolidated CDA--include the revised Continuity-of-Care Document, which the Center for Medicare and Medicare Services has proposed as the sole format for the clinical summaries that must be exchanged during transitions of care under its Meaningful Use Stage 2 rules.

In a separate interoperability initiative, pharmacy chain Walgreens recently announced that it will use Surescripts' Clinical Interoperability services to electronically deliver patient data directly to primary care providers to improve the coordination of care.

Walgreens and Duane Reade pharmacies and their affiliated Take Care Clinics will use the Surescripts network to deliver immunization records to patients' primary care providers. Walgreens will also use the Surescripts network to provide immunization reporting to state and local public health agencies, and Take Care Clinic patient summaries to the patient's primary care provider. The interoperability network is using several approaches, including the Direct messaging system and HL7 messaging.

A single nationwide health information exchange that relies on a single interoperability standard is a long way off, but attempts by Health Story, Walgreens, and others are promising.

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