First of all, the raw data received by a provider must mean something very specific to the party which receives it. There are thousands of different kinds of HL7 messages which are sent to share patient encounters or lab results for the purpose of supporting care teams. Or a doctor can send an electronic prescription to a pharmacy to be filled. In all cases patient data must move.

Unfortunately, the format of the raw data differs widely depending on the EHR system being used. Usually, the raw data, inside the message, does not mean anything outside of the context of the EHR system from which it came. Hence, it is imperative to map local coded data to an internationally agreed upon standardized reference terminology. For example, hospitals should use standardized codes for all of the drug names. Subsequently, the codes for the drug names must be compiled and regularly maintained. 

What is Coded Medical Data?

In order to understand interoperability, we must first understand how medical data is coded for storage in a patient database.

The actual data stored in the various EHR systems, such as Cerner and Epic, store codes instead of text. When a clinician selects from a drop-down list, the text is not stored, but an invisible code mapped to it. For example, hospital A may use 10520, to represent the blood type O+. Meanwhile, in a different hospital, a clinician selects the same choice O+. But the EHR system for hospital B codes O+ as 99375. As long as these codes stay inside the proprietary EHR systems, they have local meaning. Once this data is exchanged, hospital A's system does not know what to do with code 99375. It is a data error to this hospital's EHR system. Neither does hospital B know what to do with the code 10520.

This makes it very difficult for two healthcare providers to exchange any medical records. So how are we to exchange medical data when the actual file contents lose their defined meaning when outside of the local EHR system? The solution is to perform interoperability planning and map these local EHR codes to an internationally standardized set of reference codes. Then the data can be moved outside the local EHR system.

"The ability to exchange and use information, usually in a large and heterogeneous network ..." (

Many people expect medical data to be as easy to exchange as banking data or airline reservations. Unfortunately, medical data is much more complicated. The process of exchanging data is complicated by the fact that the Electronic Health Records (EHR) system code their data differently. 

International data standards, standardized reference terminologies and message standards are foundations of interoperability.

Before these HL7 messages can be consumed by an Electronic Healthcare System, the various parts of the message must be very specifically defined and agreed upon by the sender and the receiver. Part of the work which goes into design and implementation of a clinical message, which describes the clinical process involved. To this end, HL7 is an organization dedicated to creating standards for the structures of clinical messages. HL7 has developed several standards for interoperability including: HL7 Version 2, CDA Documents, and FHIR.   

Founded over 50 years ago, HL7 works to allow anyone in the world to exchange medical data. 

Consequently, many countries are cooperating to refine these international medical standards. Along with the clinical data, the security layers are transported. These govern who is allowed to see the data in the EHR record, and when and how could that be overridden in an emergency.  Roles and responsibilities are defined for each user.  A very complex dance is orchestrated to run through who can see and or change information and under which circumstances this can occur. In the case of an emergency, 'Need to know' protocols are invoked much like in a defense agency to protect patient privacy and safety.   

Interoperability Insights

80% of the challenge of interoperability is the establishment of practical and implementable data standards. The other 20% includes healthcare policy, human languages, and legal problems. This is a technical challenge which must be solved in an international arena with international standards so the effort and costs can be spread out between various countries. Canada, the U. K., Australia, Japan, Brazil, Italy, and Germany are already dedicated to data standards. Galen Mulrooney,  Exec. V.P.  J P Systems

The ideal state of healthcare interoperability would be that of healthcare providers being able to send data to each other as easily as banks can now. The real state is that of a budget driven lack of cooperation to agree on a "standard" standard.  Software vendors are a part of the puzzle.

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