What are the differences between the different types of VistA ?

This note (before editing) is from Nancy Anthracite:

By way of full disclosure before I begin, I am the CMO of WorldVistA.

FOIA VistA is released by the VA and to my knowledge, everything but the proprietary components such as the CPT codes are currently in the public domain. That makes this option attractive for those who wish to modify the code and make it into a proprietary product. Otherwise, it is a bit more difficult to configure and you do not get as many members of the community working on making things easier for use of it outside of the VA as you do if you choose another option. It can be run on Cache for Windows, or GTM on Linux, or on other systems such as the VA uses and probably for Linux, etc., but for practical purposes, outside of the VA, I think that Cache for Windows and GT.M for Linux are the two choices. Both FOIA VistA and the Patches for it are available from the VA FTP site, ftp://ftp.va.gov/vista/software/

FOIA caveats are that the VA is beginning to move to use some very expensive proprietary elements, so if this option is chosen, one must prepare to take those components on or provide their own support of the system which is probably something only experts in VistA should even consider.

Medsphere's OpenVista is a modified version of FOIA VistA with a client named CIS that is an enhanced version of CPRS compiled with Mono. The version is released under an open source license. As I understand it, updates are obtain with a support contract with Medsphere or an affiliate.

WorldVistA EHR is a slightly modified FOIA VistA which uses a slightly modified CPRS which remains 508 compliant as is CPRS. WorldVistA EHR is released under a GPL license and updates can be downloaded from Sourceforge.net. WorldVistA EHR achieved CCHIT certification in 2006 and with a proper agreement and use of WorldVistA EHR, sites could be certified for using a CCHIT certified EHR. CCHIT certification by the "old system" would have required renewal by the 2009 criteria, but things have now been changed with the advent of meaningful use and it is not entirely clear what will happen regarding future certification.

From reading Hardhats, I believe Astronaut is an easy to install, slightly modified version of WorldVistA EHR for Linux/GT.M that has more configuration done for you. It is also bundled with client GUIs that are pre-configured to function with their support RPC Calls already loaded. Updates for Astronaut presumably will be identical to those for WorldVistA EHR potentially with a few exceptions.

Enhancements for WorldVistA EHR/Astronaut enhancements may be compatible with Medsphere's OpenVista and some of Medsphere's enhancements may be used with WorldVistA EHR.

DSS announced it has an open source version of their vxVistA released under an Eclipse license. The Eclipse license is not compatible with a GPL license. I know very little about their product and I do not know whether both client and server are released under an open source license.