Use of a health information exchange can limit the number of redundant medical imaging and tests, often leading to savings for providers.
A good link roundup here by Katie Wike that includes studies and analysis from the Journal of the American College of Radiology, Fierce Health IT, and iHealth Beat.
Each report shows that use of HIE reduces costs and test redundancy. What is even more important — many of those tests involve radiation, and limiting the patient exposure is of utmost importance, especially if the exam has already been conducted.