WASHINGTON (AP) — More than 16 million Americans have gained coverage since President Barack Obama's health care law took effect five years ago, the administration said Monday.
But measuring a different way, an independent expert who took into account insurance losses during some of those years had a much lower estimate: 9.7 million.
The Department of Health and Human Services estimated that 16.4 million adults have gained health insurance since the law's major coverage provisions began taking effect in 2010.
The lower independent estimate is based on a large daily survey called the Gallup-Healthways Well-Being Index.
There seems to be no dispute that Obama's law has significantly reduced the number of uninsured Americans. The question is, by how much?
It will take time for authoritative statistics to emerge, particularly when the government and outside experts are using different estimating methods.
The HHS estimate comes as the administration prepares to commemorate the fifth anniversary of the law's signing on Mar. 23, 2010. The Affordable Care Act has been politically divisive from the start.
HHS Secretary Sylvia M. Burwell said it's brought about "the largest reduction in the uninsured in four decades."
Democrats hailed the law's passage as the culmination of decades of effort to guarantee health coverage for all Americans, including people with health problems who previously could be turned away by insurance companies.
Republicans called it government overreach, and haven't stopped trying to repeal or roll back what they dismiss as "Obamacare." That opposition has helped the GOP win control of Congress.
The health care law offers subsidized private coverage for people who don't have health insurance on the job, along with an expanded Medicaid program that a majority of states have accepted.
According to the HHS estimate, 14.1 million adults got their insurance after the law's big expansion began at the end of 2013. HHS said it used Gallup-Healthways data to arrive at that figure.
Even before that, another 2.3 million people had gained coverage under a provision that lets young adults stay on a parent's plan until age 26, the administration said. HHS reached that estimate using data from a different source, a government survey.
The administration says that means 16.4 million people gained coverage since Obama's law took effect. The White House said that's the total number of people who would likely have been uninsured were it not for the law.
Gallup's lower number was computed in a different way.
Dan Witters, research director for the Gallup-Healthways Well-Being Index, said his survey shows the uninsured rate declined from 16.3 percent in early 2010 to 12.3 percent this year among adults 18-64. That translates to about 9.7 million fewer uninsured adults over that time period.
Witters said he has not had time to review the government's methodology.
But he noted that the uninsured rate has fluctuated during the past five years. On balance, fewer young adults went without coverage starting in 2010. However, older adults saw coverage losses until 2013 and the opening of the health care law's insurance markets.
Witters added he would want to know more about how HHS combined its two separate estimates to arrive at the figure of 16.4 million gaining coverage.
HHS official Richard Frank, in charge of the government report, said the two numbers "can be added together as coverage gains associated with our policy."
But asked if the overall figure represents a net reduction in the US uninsured rate in the five years since the law's passage, Frank responded "that is not precisely what they represent."
He said they are "two sets of net reductions, but they are slightly separate in the analysis."
The administration said all racial and ethnic groups have seen gains in coverage, but the biggest improvement has come among minority groups such as Hispanics and African Americans. States that agreed to expand Medicaid continue to outperform those that did not broaden coverage for low-income people.
The law's coverage gains haven't settled the political debate. Republicans now in charge of both chambers of Congress remain committed to repeal, although Obama is sure to veto any such legislation.
The biggest question hanging over the law now is a Supreme Court case in which opponents argue that subsidies are illegal in most states. They contend that the exact wording of the law only allows subsidized coverage in states that have set up their own insurance markets, and most have not done so, relying instead on the federal marketplace. The administration counters that the context of the law makes it clear the purpose was to expand coverage in every state.
Independent estimates say about 8 million people could lose coverage if the subsidies are rolled back. A decision is expected by the end of June.