The divide between health outcomes for the richest and poorest Americans is among the largest in the world, according to a new study.

Of people in households making less than $22,500 a year, 38 percent reported being in poor or fair health in a survey taken between 2011 and 2013. That’s more than three times the rate of health troubles faced by individuals in households making more than $47,700 a year, where only 12 percent of people reported being in poor to fair health, according to the findings published in Health Affairs.

While wealthy people around the world generally have better health outcomes than their fellow low-income citizens, the gap in the United States was among the world’s largest. Of the 32 rich and middle-income countries studied, only Chile and Portugal had a wider gulf.

The timing of the study is important — it was conducted just before many of the Affordable Care Act’s major policies were enacted. A major facet of the ACA was a redistribution of income, a tax on the richest Americans that helped pay to expand health coverage for the country’s poorest, and the study’s authors said it suggests that any reduction in coverage could be a step backward, in an area where the United States has been underperforming.

Now the policies that expanded health coverage are on the chopping block. A recent Congressional Budget Office analysis found that the latest version of House Republicans’ proposal to replace the ACA would leave 23 million more Americans uninsured than under current law by 2026. Senate Republicans are crafting their own health-care bill.

“Anything, any changes that are made that threaten to undo gains in insurance that have occurred since the Affordable Care Act . . . would risk setting us back in an area where the U.S. is in sore need of improvements,” said Joachim Hero, who recently earned his doctorate in health policy at Harvard University and led the study. But he and his co-authors caution that there’s more to closing the health outcome gap than providing insurance. When the researchers tried to do more of an apples-to-apples comparison by adjusting for whether people had insurance or not when making the cross-country comparison, they found that the disparity was only slightly decreased.

Read more: America is a world leader in health inequality – The Washington Post