Despite the technology community’s persistent interest in that which is new, in healthcare a comparatively ancient integration technology is still used for many (possibly even most) integration projects: HL7 2.x.
This interfacing technology has been used for a long period of time and is capable of transmitting large amounts of data in a format that is both relatively standardized and flexible. Information in such interfaces are sent in messages that are structured as segments of text broken up into specific fields (in a way, it is analogous to a spreadsheet with columns and rows, but each segment and field can be a different length and data type).
Sending systems such as EMRs, LIS (lab information systems), and PACS radiology systems generate messages when specific workflow triggers are achieved such as creating a new patient, completing an order, or scheduling a visit.
There are some common variants that are used more often than not.
• ADT (Admission, Discharge, and Transfer) – An ADT interface is used to transmit primarily demographic information. Messages are created when a patient account is created, patient information has been updated, when a patient has been moved from one bed to another, or when a patient is discharged. This is likely the most common HL7 interface.
• SIU (Scheduling Information Unsolicited) – This is another extremely common interface that is used to transmit scheduling information from one system to another. An extremely common use is when an organization has a separate scheduling or practice management system from their medical record (i.e., there are two products possibly a centralized practice management product and then various specialty EMRs). An SIU interface can transmit appointment information and ADTs to the EMR from the practice management system to ensure that patient IDs and demographics are consistent throughout the organization.
• ORM Message – An ORM interface sends orders to another system. For example, a physician may enter a lab order in their EMR and send an ORM message to the LIS.
• ORU Message – An ORU message transmit the results of an order. An order can include such categories as labs, cardiology tests, and radiology tests. A useful benefit is that encoding can be used to include a PDF or text formatted interpretation of the result to the receiver to allow for even more detailed information to be sent in a standardized way. For example, the PDF of an EKG waveform with the interpretation can be encoding and enclosed in the ORU message sent from the cardiology information system to the ordering physicians EMR.
Implementing an HL7 interface often requires at least one recipient to have an integration engine such as Interfaceware’s Iguana or QSI’s Mirth to process the messages and perform any transformations needed to ensure that it is processed correctly.
This can be done on either end (and sometimes on both); moreover, an integration engine allows for the interface data to split and sent to multiple locations or systems if desired. A party seeking to use an integration engine will need to involve an interface programmer to assist in configuring the system and programming any transformations needed.
Connectivity is extremely flexible with HL7 interfaces. At the most primitive level, some simply use sFTP (Secure File Transfer Protocol) to batch messages over periodically, others use a VPN and mLLP (low level protocol) to send messages through a direct connection between the sender and the receiver, and others use web services that either push or pull messages.
In the latter case, a pull process would require the receiver to send a request periodically to receiver all messages since the last request; whereas, a push process would involve the sending system to send messages over as they are generated.
While HL7 2.x relies on older technologies than some new integration options (e.g., APIs), it is a mainstay in healthcare, and it will likely persist for the time as it is a vital component to many different workflows both between entities and within healthcare enterprises.
Its flexibility is one of its primary benefits along with its near universal support.