VistA has been a very successful open source project and is being continued in OpenVistA [1]. Originating as a software project in the Veterans Administration (named VA MUMPS) in 1977 it only took on the name VistA in 1994[2]. Internationally it has been used freely in hospitals in the U.S., Mexico, India, various countries in Africa, ...[3].

It was a truly open source project within the VA with programmers customizing this national patient record software in cooperation with doctors (to meet their needs) locally and sharing the modifications nationally. Perhaps its greatest technical challenge (besides complexity arising from decades of evolution) was finding programmers to work with the MUMPS language that it was written in. FYI MUMPS is a language with an integral db -a concept which was out of vogue for some time.

Political challenges are another story[4].

[1] https://sourceforge.net/projects/worldvista/ [2] https://www.hardhats.org/history/hardhats.html [3] https://worldvista.org/AboutVistA [4] https://www.politico.com/agenda/story/2017/03/vista-computer...

As far as software success goes, all healthcare providers at the VA have used VistA daily for a couple of decades (actually CPRS -- it's like an MFC app or something on top of VistA). A relative who works at the VA likes it, and is not excited about moving to Cerner.

Why Cerner? I don't know.