Most existing Medicare-for-All projections assume that when everybody in the United States finally has the ability to seek medical care that’s free at the point of service, people will head to the doctor in droves, and this will cause a major increase in overall health-care expenditures.

Researchers usually factor a large spike in utilization into their cost estimates for Medicare for All. For example, a recent estimate from the Urban Institute assumes that health-care spending will rise 20 percent because of more frequent hospital care and doctor visits. This contributed to their conclusion that federal expenses would increase $32 trillion over ten years, an especially high estimate.

But what if the common wisdom about increased utilization is wrong? A new paper in the Journal of General Internal Medicine authored by Adam Gaffney, Steffie Woolhandler, and David Himmelstein, who teach at Harvard Medical School and lead Physicians for a National Health Program, presents some evidence to the contrary. The authors reviewed thirteen universal coverage expansions in eleven wealthy nations over the course of eight decades, and they found that overall increases in use of services were mostly either modest or nonexistent.

When the United Kingdom introduced the National Health Service (NHS), people who had been previously uninsured did start to go to the doctor more often. But this was partially offset by a decrease in utilization from higher-income people who had already had access to health care. The same thing happened in Canada — low-income people were finally able to go to the doctor, and they did, but their wealthier counterparts actually started going less. Overall usage was relatively stable, but the distribution of care became more equitable.

From Finland and Sweden to Portugal and Greece, the study’s authors found no major spike in overall utilization rates after implementation of universal health care. What did happen in these countries was that people who had previously been unable to afford a visit a doctor were finally able to seek necessary care. But universal coverage didn’t cause a tidal wave of care-seekers, as many researchers now predict will happen in the United States if we implement Medicare for All.

“In general, coverage expansions led only to small or often no overall increases in hospitalizations or the use of physician services,” says Adam Gaffney, one of the paper’s authors. “In many instances, what seems to have happened is that these coverage expansions directed more services toward those who were newly covered, but at the same time, doctors provided slightly less (likely unnecessary) services or elective procedures to well-off individuals.”

The authors point to a missing piece in the prevailing approach to cost estimates: supply. At any given time, a country only has so many physicians, and they stay busy. When there are large numbers of uninsured or underinsured people, those physicians tend to provide less care to people who can’t afford it, and more to those who can. But when coverage is expanded, those same physicians start providing more necessary care to those who might otherwise not even seek it, shifting their focus away from providing often low-value and unnecessary care to the healthy and wealthy.

Thus, the study’s authors conclude, “History suggests that coverage expansions such as Medicare-for-All redirect care to the poor and sick, but need not drive up overall utilization if growth in supply is regulated.”

Ultimately, what we’re aiming for is a society in which every person gets the care they need. When you have large populations of uninsured or underinsured people and huge out-of-pocket expenses, the available supply of physician services is distributed unequally: people who desperately need care can’t get it, while at the same time there is an abundance of services available to those who don’t really need it. Universal health coverage evens it out, refocusing physician time and attention on healing the sick, whoever they may be.

Not only will Medicare for All probably cost less than many estimates suggest, but it will also result in a more equitable distribution of medical care. “When financial barriers to care are erased, in other words,” says Gaffney, “patients get services on the basis of their medical needs — not merely because they are well-to-do.”