Evidence Based Design while still a fledgling process, seeks to provide hard data to verify if design concepts executed in healthcare construction really contribute to improved hospital environments and patients.
But just like Post Occupancy Evaluation information that architecture firms try obtain from clients, it takes a commitment from the client to collect the data to share with the designers. They often see it as important to their consultant but not to the hospital.
A recent NBC News post had some confusing reporting according to Sara Marberry, a Knowledge Expert in Healthcare Design, she discusses it at length here: http://www.saramarberry.com/believe-evidence-based-design/
And she explains more about evidence based design in this post on the 8 steps of EBD research: http://www.saramarberry.com/going-all-the-way-with-evidence-based-design/
Sara Marberry EDAC has a Blog covering EBD and healthcare design in general that is very informative, and well written, follow her blog: http://www.saramarberry.com/blog/