MIAMI, FL - DECEMBER 11: Marlene Gonzalez (L) sits with Alberto Gonzalez (C) as they and Marinely Perez (R) speak with insurance agents with Sunshine Life and Health Advisors about purchasing insurance under the Affordable Care Act at a kiosk setup at the Mall of Americas on December 11, 2013 in Miami, Florida. As Health and Human Services Secretary Kathleen Sebelius tesified in Washington, DC before a congressional panel that the Affordable Care Act website was improving, the Sunshine Life and Health Advisors said, that they are starting to see a steady increase in the numbers of people coming to them to purchase and understand the policies offered under the Affordable Care Act. (Photo by Joe Raedle/Getty Images)

In health care, as in the rest of American life, the gap between rich and poor is growing. That's the take-home message from our analysis of 50 years of data on health care use and expenditures that appears in the July issue of the journal Health Affairs.

In the bad old days of the 1960s -- before Medicare and Medicaid -- the wealthy got twice as much care as the poor. But those programs changed things. By 1977, the poor were getting 14 percent more care than the wealthy -- an appropriate difference since the poor are sicker and need more care.

The pattern changed again in 2004. Over the next eight years, use of care by the wealthiest fifth of Americans grew by 19.7 percent, outpacing growth for the middle class by 57 percent. Meanwhile, care for the poorest fifth actually fell.

By 2012 the wealthy were getting 40 percent more doctor visits than other Americans. Overall, after adjusting for differences in age and health, the wealthy got 43 percent more care than the poor -- $1,743 per person -- and left the middle class in the dust too; the latter got $1,082 less care than the rich.

What's behind widening health care inequality?

Ballooning copayments and deductibles are the most likely culprits.

As health care costs soared, employers shifted more and more of the burden to their workers. Over the past decade, the average deductible in employer-sponsored health plans has risen 255 percent.

Where the copay for a trip to the doctor used to be a few dollars, now it's often $50. An MRI or night in the hospital? We're talking hundreds, or even thousands of dollars out of pocket.

With incomes of the poor and middle class stagnant or worse, many Americans don't have that kind of money; half can't afford an unplanned $400 expense without borrowing money or selling off a possession. That leaves many facing a choice between debt and care. Medical bills have become collection agencies' biggest business.

Health policy wonks have applauded rising deductibles and copayments as the right way to get health care inflation under control - they call it giving patients more skin in the game.

But as doctors we've seen the human toll these policies exact: Women who waited and hoped that their breast lump would just disappear. Men with strokes because they couldn't afford high blood pressure treatment.

Obamacare offered a partial solution to health care inequity by covering about half of the uninsured. But the health law is also part of the problem. The new insurance policies demand punishing deductibles -- an average of $3,064 per person in the exchanges' silver plans, and even more, $5,765, in the bronze plans. And after paying that, patients still face steep copayments.

That kind of insurance is akin to a hospital gown: it gives the impression that you're covered, but doesn't actually cover your butt.

The health care inequality we found is uniquely American. In every other wealthy nation, people are shielded from the costs of illness by a comprehensive and truly universal national health insurance program.

Every Canadian, for instance, has first-dollar coverage through a Medicare-for-all system (they actually call it "Medicare") that distributes care according to need, not wealth. As a result, poor Canadians get 26 percent more care (and the middle class 11 percent more) than the wealthy.

The growing inequality in health care use in America is reflected in worsening outcomes for those with lesser incomes. While the health gap between rich and poor Canadians has been closing, ours has been widening. Today, the wealthiest American men live 15 years longer than their poor counterparts.

For the past decade or more U.S. health policy has blamed patients for skyrocketing health costs, and sought solutions in ever-skimpier insurance coverage and market-based competition.

Those policies have fueled a boom for giant insurers, drug firms and hospital chains. But they've been a bust for poor and middle-class Americans.

Drs. Steffie Woolhandler and David U. Himmelstein are primary care physicians, professors of health policy at the City University of New York at Hunter College, and lecturers in medicine at Harvard Medical School. They co-founded Physicians for a National Health Program (pnhp.org), a nonpartisan organization that advocates for single-payer health reform.

This article originally appeared at The Hill. The views expressed by contributors are their own and not the views of The Hill.