Medical expenses remain out of control in the U.S., where Americans have an "unsustainable attitude" that ignores the increasing cost of health care, the chief executive officer of insurer Aetna Inc. (AET) said. While the rise in medical costs has slowed since the last recession, the U.S. still needs to switch to a "fundamentally different" system that pays for the quality of care rather than the quantity, Mark Bertolini said in a Bloomberg Television interview from Davos, Switzerland. "Our health-care costs are not under control right now," Bertolini said. "We really need to look at how health care is delivered and how we pay for it. Today, we pay for each piece of work done and so we get a lot of pieces of work done."