The trend over the last two or three years for many health care facilities has been to move to integrated systems.  This is a brief discussion of what integration can achieve vs. what interfacing can achieve.  Both approaches have pros and cons. This section discusses Interfaces.

Interfacing systems is a good solution for facilities that want the best possible applications for each function.  However interfacing brings its own issues as well as benefits.  Interfacing two or more applications which utilize different data base and data structures can be complex.  Each interface requires the cooperation of the vendors involved as well as the IT department of the facility.  Interfaces always require more IT involvement and maintenance than integration.  Most interfacing is now done utilizing an interface engine.   The interface engine controls the files passing back and forth between applications and is often used to direct the file to additional destinations.

In addition to the interface engine additional hardware may be required for interfacing.  Many applications require their own interface server which has no other purpose than to run the interface programs.  These programs are generally used to generate the data file, maintain backups of the data files and route the information to the engine or the receiving application.

Interfaces can be run without user intervention such as an ADT(Admission, Discharge, Transfer) interface which is constantly polling the application for new data.  This is an example of a real time interface.  Interfaces such as billing interfaces are usually batch interfaces.  This type of interface may require user intervention to generate the data file and initiate the interface program.  Many batch file interfaces can also be programmed to execute once a day at a specific time or several times throughout the day.

Utilizing interfaces to achieve system integration can connect many disparate applications.  The data is normally formatted using HL7 specifications.  HL7 is an industry standard format for passing data from one application to another application.  The vendors must agree upon which data fields will be used and the format of the data within the fields.  Before HL7 standards became utilized many vendors used flat ASCII files or proprietary file formats to interface data.  This always required custom formatting and programming.

This is one of the main issues in the ARRA HITECH. Intraoperability between systems is a key point in EHR functionality, including lab, CPOE, and eRx.