If the United States' health system was a high-school student, its latest report card would be mediocre, at best—but next quarter could see some real improvement if that "Obamacare" tutor works out, a new study suggests.
The Commonwealth Fund's "scorecard" of the nation's states released Wednesday shows that a majority of them either declined or failed to improve on nearly two dozen health indicators from 2007 to 2012—a period of time before the Affordable Care Act began to take full effect.
The group noted that during that time the overall rate of uninsured working-age adults grew to 21 percent from 19 percent nationally, and health care became less affordable, leading to a reduction in the number of people seeking needed care because of cost barriers.
And not only was the nation in a rut during those years when it came to improving the overall health system—which includes access to services, quality, costs and outcomes—but there were wide gaps in performance between individual states, the Commonwealth Research found in its report "Aiming Higher: Results from a State Scorecard on Health System Performance, 2014."
Top-performing states sometimes performed between two-to-eight-times better than the worst-performing states when it came to things such as the rate of elderly people receiving high-risk medication and the number of children hospitalized for asthma, the report found.
"There has been little progress among states leading up to the major coverage reforms of the Affordable Care Act," said David Blumenthal, president of the Commonwealth Fund.
The scorecard noted that during the time frame that was examined, health-care spending in the U.S. grew by nearly $500 billion annually, reaching $2.8 trillion.
"And still, the scorecard points to deteriorating access to care for adults, stagnant or worsening performance on other key measures such as preventative care for adults, and widespread disparities in peoples' health-care experience across and within states," the report said. "These findings suggest that the return on our nation's health is falling woefully short."
The group did identify a handful of bright spots, including 17 states seeing reductions in their rates of uninsured children by at least two percentage points. A majority of states also saw improvements in the rate of childhood immunizations, avoidable hospital readmissions and cancer-related deaths.
However, Blumenthal added that even states above average in the 42 health indicators are far from perfect.
"There is room for improvement also in every state," he said.
The report found that if all states achieved top rates of performance in the indicators measured, there would be 35 million more insured adults and children, 25 million more adults with a usual source of primary care, and there also would be 18 million fewer adults who would go without care because of its cost.
And, strikingly, the report said there would also be 84,000 fewer deaths of people under the age of 75 from treatable diseases.
The years reviewed by the Commonwealth Fund include ones that bore the brunt of the Great Recession, and those were the most pronounced. Also, Obamacare's requirement that nearly all Americans have some form of health insurance or face a tax penalty was not yet in effect, as it is this year for the first time.
The best-performing states on the scorecard were clustered in the Northeast and upper Midwest, with Hawaii also scoring well. In contrast, the worst-performing states were largely in the South and Southeast, with Nevada also trailing the much of the rest of the nation in metrics such as preventable deaths for people under the age of 75.
"In the U.S., where you live has long been a major influence on the kind of health care you receive," Blumenthal said. "That shouldn't be true."
But Blumenthal noted that "the Affordable Care Act has the potential to level the playing field, as all states have the opportunity to make substantial improvements to the health-care systems if they take full advantage of the provisions of the law."
Blumenthal was specifically referring to the ACA's provision allowing individual states to expand their Medicaid eligibility standards to include nearly all poor adults. About half of the states have expanded Medicaid, with the federal government picking up the tab for the newly eligible for three years, and 90 percent of the costs thereafter.
"Notably, 16 of the states at the bottom half of the scorecard have not yet decided whether to participate in Medicaid expansion," said Cathy Schoen, a Commonwealth Fund senior vice president, and a co-author of the scorecard research.
Those include three states at the very bottom of the scorecard, Mississippi, Oklahoma and Louisiana, where the rate of uninsured adults ranged between 22 percent and 28 percent from 2011 to 2012.
But Schoen cautioned that to improve the overall health system of the U.S., "it will not be enough to give insurance cards to everyone."
"We will need to improve the care system," she said.
An article about that scorecard that also was published Wednesday in the Journal of American Medicine by Schoen and her fellow scorecard authors noted that among the few indicators that saw improvement in a majority of states from 2007 until 2012, "there was often concerted, coordinated attention to improvement at federal, state and local levels."
"These successes suggest an opportunity for physicians to join with others to exert leadership in both medical practice and the policy arena so that such gains become the norm in coming years," the article said.
"With new resources and tools provided by national reforms, this opportunity extends across all states."
—By CNBC's Dan Mangan.