How does HL7 fit into EHR / EMR interoperability?

Modern healthcare technology needs to communicate and share information with others. That seems like an obvious statement. However, this has not been the legacy of the health IT industry – historically, Electronic Health Records (EHR) have been built as large, all-inclusive enterprise systems designed to function within a closed network environment.

In this setting, interoperability was not a key priority – after all, “everything you’d ever need” was already within the product. If anything, exchanging data with others was like “making nice with the competition.”

However, the national health IT policy as articulated by the Office of the National Coordinator (ONC) is focused on building a nationwide electronic health information infrastructure, in order to avoid medical errors, measurably improve clinical performance, improve patient access to their own health information, and reduce disparities in healthcare. And interoperability of health data is a key part of that.

So how should health data be communicated? There actually is a divergence of opinion about that – perhaps dubbed a “legacy approach” and a “web approach.”

The legacy approach
Given that legacy systems function behind the closed walls of their networks, it is not feasible for them to look into each other’s systems in any easy way. Instead, what legacy systems have to rely on is packaging up different pieces of data into (basically) a text file, and transmitting it securely to someone else. The main content-standard for these files has been HL7.

Health Level 7 (HL7) is an organization created by many large institutional players in over 55 countries, which try to agree on a standard format for all sorts of data exchange. HL7 has created Messaging Standards (version 2.3.1 and 2.5.1 are specifically mentioned in HHS Certification specs), as well as standards for Continuity of Care Documents (CCD), and Clinical Document Architecture (CDA) files. These standards describe structured data put together into a text file, and are how lab results are reported, immunization registry data is exchanged, public health events are reported, and legacy EHRs exchange clinical summary data with each other.

Other approaches to data exchange seen elsewhere also follow a method very similar to HL7 – the NCPDP standard for transmitting prescription information to the prescription clearinghouse (Surescripts) is a file structure very reminiscent of HL7.

In short? Legacy systems need to have agreed-upon file formats on which to write health data, so everyone knows what-goes-where and can report and consume such files. The transport of these encoded files can take place a number of ways – from FTP downloads, to secure web transport, to even modem-based bulletin-board BBS posting-and-download (Kermit protocol). So, legacy systems need to agree on (1) content of structured text files, and (2) secure transport methods.

Web approach
Internet technologies are built differently. To begin with, a web application is intended to be shared widely, not behind a closed wall. Security and permissions are therefore key for a web application – a good example is web-based personal banking. Web applications make use of “ web services,” which expose selected functions and features to authorized requestors. For instance, a credit-card payment piece of an e-commerce web site is typically a web service that is external to the e-commerce vendor, but functions seamlessly together for a unified end-user experience.

Web-based health IT is an emerging technology. Recognizing this, the department of Health and Human Services (HHS), along with Health 2.0, has launched a Developer Challenge to encourage web-application developers to come up with innovative solutions. Think “an App Store for health IT.”

These kinds of web-based solutions use web services to communicate with each other. They do not use HL7, or other legacy methods. It is true that such apps must be able to use HL7 documents (generate them and import them) in order to remain backwardly-compatible with large, legacy systems. But that is not necessarily the way of the future. Or at least, not the only way of the future.

Over the next 6 or 12 months, some very exciting collaborations are sure to emerge within the web-based sphere of health IT (so-called “Health 2.0 companies”). They will be based on sharing data using web-services, and not HL7. But – to be fair – as long as large systems, such as laboratories and prescription clearinghouses, remain as important centers for health information needing to be exchanged, then backwards-compatibility with their methods will need to be maintained. But future growth will be in a web-based direction. These will be exciting times!

Robert Rowley, MD
Chief Medical Officer
Practice Fusion EMR