We found that utilization rates in some major categories, including emergency departments and ambulatory surgery or procedures, generally were 20-30 percent lower in Medicare Advantage HMOs in all years. Medicare Advantage HMO enrollees initially had lower rates of ambulatory visits and hospitalizations, although these rates converged by 2008; they also received about 10 percent fewer hip or knee replacements. In contrast, HMO enrollees underwent more coronary bypass surgery than patients in traditional Medicare. These findings suggest that overall, Medicare Advantage HMO enrollees might use fewer services and be experiencing more appropriate use of services than enrollees in traditional Medicare.
Entire Health Affairs study on Medicare Advantage vs. traditional Medicare.