Volume-based referral policies do not appear to steer patients toward hospitals with high average costs for inpatient surgery in the elderly. A University of Michigan study found that the lowest-volume hospitals had considerably higher case-mix-adjusted episode payments for CABG and abdominal aortic aneurysm surgeries, but not for colectomy, when compared with the highest-volume hospitals.

Abstract: Journal of the American College of Surgeons, December 2012.