J.P. Morgan CEO Jamie Dimon renewed his criticism of health care in the U.S. on Wednesday, saying Americans have some of the "worst outcomes" despite having the best system in the world, he told CNBC's "Squawk Box."

"With health care, we have the best in the world — doctors, hospitals, pharma, you name it — but we also have some of the worst outcomes," he said in an interview at the World Economic Forum in Davos, Switzerland. "Obesity, wellness programs that could work better, the opioid problem, 40 million uninsured. So you know, to me, you look at the whole issue and what should we do about it."

Dimon has been a vocal critic of how much the nation, and especially employers, pay for health care. He teamed up last year with Berkshire Hathaway CEO Warren Buffett and Amazon CEO Jeff Bezos to form a joint venture aimed at tackling costs and hopefully providing better services for their employees.

In June, the trio named a prominent surgeon and health-care thought leader Dr. Atul Gawande to lead the still unnamed initiative. The group also hired Dana Gelb Safran, formerly a chief performance measurement and improvement officer at Blue Cross Blue Shield of Massachusetts as "head of measurement."

For now, the group is focused on building out its team and "looking at how to attack this problem," Dimon said Wednesday.

"It's a long-term view. We don't expect any announcement anytime soon," he said. "We will share if we come up with anything good, but we want to start small. Test a bunch of different things."

Health-care spending represents nearly 18 percent of the U.S. gross domestic product, far more than other developed nations, a statistic that Dimon pointed to as one that's unsustainable and that leaves American business at a disadvantage to foreign competitors.

"If you look at it as a competitive issue, that is a huge impediment to American business over the next 50 years," he said.