A new report from the Commonwealth Fund adds to the evidence that the embattled Affordable Care Act has been doing its job.  Since the law's implementation, the number of people without health insurance has dropped in all states. It fell by at least three percentage points in 48 of them and the District of Columbia.

The rates are now at "historic lows," said David Blumental, president of the Commonwealth Fund, a private foundation that supports research on healthy policy issues.

"The historic decline in uninsured rates has been accompanied by widespread reductions in cost-related access problems and improvements in access to routine care for at-risk adults," the report said.

Republican leaders and president-elect Donald Trump have vowed to do away with the health reform law, also known as Obamacare, but have not revealed clear plans for what they would do instead.  The report said the impact on consumers of changing the law will depend on its replacement.  It quoted an analysis by RAND that concluded that 20 million people would lose health insurance by 2018 if the law were repealed.

The law was passed in 2010 after years of rising rates of uninsurance.  According to a November report from the U.S. Centers for Disease Control and Prevention, the percentage of  working-age adults (18 to 64) without insurance was 18.9 percent in 1997 and rose to 22.3 percent in 2010.  It's been falling ever since.

Insurance matters, Blumenthal said, because "a large body of research" has tied having it to better health.  Without adequate insurance, people are more likely to delay care until they have serious problems.  They also may not be able to afford prescribed care.  From a policy standpoint, when some patients aren't able to pay for the care they receive, it means that providers like hospitals must raise prices for everybody else.  This, he said, leads to a "hidden tax" that is absorbed by paying customers.

Whatever changes in the law, he said, it is best for the nation's health if the trend is toward more coverage, better access and improved quality and affordability.

The new report, which was released Wednesday, found that the percentage of American adults (19 to 64)  without insurance dropped from 20 percent in 2013 to 13 percent in 2015. Thirteen percent of adults still said they went without care because of the cost last year, down from 16 percent in 2013.  The states with the biggest improvements were those that had expanded eligibility for Medicaid as soon as that was possible.

The trend was similar in this region.  Rates in New Jersey, which most surveys find are better than the national average, were almost the same as the nation's in the Commonwealth Fund report. The number of adults without insurance fell from 19 percent in 2013 to 12 percent last year, the report said.

Pennsylvania and Delaware were better than the national average to begin with and stayed that way, according to the report.

In Pennsylvania, the percentage for adults without insurance fell from 14 percent in 2013 to 9 percent in 2015.  The rate in Delaware dropped from 14 percent in 2013 to 8 percent last year. (New Jersey and Delaware opted into the Medicaid expansion the first year, 2013. Then-Gov. Tom Corbett waited a year before implementing a private-market alternative in Pennsylvania that took effect just as his successor was being sworn in; Gov. Wolf spent much of 2014 transitioning the program to the standard expansion that the federal law had envisioned.)

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