“It would be nice if giving people insurance did get them so healthy and so much access to other care that they didn’t need to go to the emergency department, but that does not seem to be the case,” said Katherine Baicker, dean of the University of Chicago’s Harris School of Public Policy. “It seems clear to me that expanding insurance, in and of itself, does not contain spending. It increases spending, by giving people who had very limited access to care the ability to get their health-care needs met.”

Another Health Affairs study poked a hole in a different health-care mantra: that the key to cutting spending is to coordinate care for high-risk patients with chronic diseases, to keep them out of the hospital.

The study examined accountable care organizations, groups of hospitals and doctors that work together to improve health care and reduce costs. There were savings overall, but they weren’t mostly from reductions in spending on high-risk patients. The researchers measured some modest increases in hospitalizations for avoidable procedures, one of the categories of care that would be expected to be affected by efforts to help high-risk patients stay well.

These studies both chip away at ideas that stem from the overarching belief that improving the quality of health care will also save money.

“It turns out, when you do the math, it’s just very tough to save money when you’re doing things to improve quality. It’s very hard to save a dollar when you spend a dollar,” said J. Michael McWilliams, a professor of health-care policy at Harvard Medical School. “Why has this become such a widespread notion — that we can sort of coordinate our way out of the cost problem? One reason is that it’s a much easier conversation to have: We can all subscribe to this notion of prevention saves money and care coordination saves money — and we don’t have to talk about regulating prices, or breaking up monopolies.”

By now, it shouldn’t be a surprise that getting health coverage doesn’t drive down emergency room usage. A provocative study four years ago found that expanding Medicaid in Oregon had caused emergency room visits to increase. A follow-up study last year found the surge in ER visits wasn’t temporary at least two years out.

The study did find one possible reason the myth hasn’t died. Uninsured people used other kinds of care — such as visits to a doctor or other hospital departments — far less than insured people. That could contribute to the perception that they’re using the emergency room more, since they are so rarely seen in other care settings.

There are reasonable arguments for providing health coverage to uninsured people and helping chronically sick people better manage their diseases. But policymakers often return to the idea that such interventions will improve quality and costs, in one swoop — even as the evidence points to another conclusion.

“Just because something sounds true doesn’t mean that it is,” Baicker and Amitabh Chandra of the Harvard Kennedy School of Government wrote in a recent article in the New England Journal of Medicine calling for the use of more evidence in health policy. “And magical thinking won’t improve our health care system.”