The Affordable Care Act (ACA) turns 10 years old on Monday. To celebrate the law's "tin anniversary," researchers and experts are looking at ways the ACA has improved the U.S. health system—and areas where the ACA has fallen short. And, with a looming legal challenge, many are wondering whether the health reform law will survive another year.

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ACA spurs major declines in the US uninsured rate, but progress has started to reverse

The most significant change the United States has seen because of the ACA is a drastic decline in the number of Americans without health insurance.

The ACA expanded Americans' access to health insurance in four notable ways: creating the federal and state insurance exchanges and subsidies to help qualifying Americans pay for exchange plans, allowing states to expand their Medicaid program's income eligibility thresholds, barring insurers from denying coverage or charging higher rates to individuals based on pre-existing medical conditions, and allowing young adults to remain enrolled in their parents' health plans until age 26.

The U.S. uninsured rate reached a high point at 16.3% in 2010, when the ACA was signed into law, but declined after the ACA's passage, reaching 14.5% in 2013—the last year before the ACA's exchanges, Medicaid expansion, and pre-existing condition protections took effect. The uninsured rate then continued to decline from 2014 to 2017, falling to 8.8% in 2016 and 7.9% in 2017. However, the country's uninsured rate then began ticking back up, climbing to 8.5% in 2018.

Observers have hypothesized that the recent increase in the U.S. uninsured rate is tied in part to changes put in place by the Trump administration, such as allowing states to implement Medicaid work requirements, shortening the open enrollment period for the federal exchange, and reducing funding for outreach regarding the ACA's open enrollment period. The occurrence highlights the fact that, although the ACA made great strides in increasing Americans' access to health coverage, there are still many in the United States who are uninsured—and the health reform law on its own might not be the solution to that problem.

ACA improved patient outcomes and health care disparities, but progress is limited

Research also has shown some progress around heath care-related disparities and patient outcomes since the ACA became law, though the health reform law's effects in those areas aren't as widespread as some might have hoped.

For instance, various studies analyzing the ACA's effects over the past 10 years found mixed results on these topics. For example, one study found "that there have been promising improvements for certain health outcomes, including early-stage cancer diagnosis and cardiovascular health," but noted that "results for self-reported physical and mental health are mixed."

And the ACA's effects on reducing health-related disparities among certain groups appear even less clear. For instance, researchers in one study wrote that the ACA drove "some of the most significant advances for women's health in recent decades through its increased access to health insurance and health care for women." However, the researchers also noted that many disparities persist, particularly "among members of racial/ethnic minority groups and low-income women."

A recent report from the Commonwealth Fund also found that while the ACA spurred notable progress in addressing racial disparities in uninsured rates and access to care, that progress appears to have stalled since 2016.

ACA helped nudge nation toward value-based care, but effects are murky

The ACA also aimed to shift the United States away from its fee-for-service health care system that pays clinicians based on the amount of care they provide to a value-based system that ties clinicians' pay to quality of care and patient outcomes. The law created the Center for Medicare & Medicaid Innovation (CMMI), which has launched several voluntary value-based payment programs for clinicians and is gearing up to launch more—as well as some mandatory value-based payment programs.

But experts are still weighing whether these value-based initiatives work, health economist Austin Frakt recently noted in the New York Times' "The Upshot." For instance, Frakt wrote that initial analyses of Medicare's Hospital Readmissions Reduction Program suggested the initiative reduced hospital readmissions and saved Medicare billions of dollars per year, but later studies found the numbers in the reports were overstated. Meanwhile, a study examining the Medicare's Hospital Value-Based Purchasing program found "no effect from financial incentives of the program on quality of care," Frakt wrote, while another study found no differences in changes in mortality rates between hospitals in the program versus hospitals exempt from it.

Conversely, Frakt wrote that evidence has suggested CMMI's bundled payment programs have had some success; and that research has shown ACOs reduce spending without lowering quality—though the savings vary by program design.

ACA's future unclear

While the ACA's overall effects might still be foggy, many have touted the positive effects the United States has definitively seen because of the law, such as the proven increases in many Americans' access to coverage and care. While disparities remain, some progress is better than no progress at all, they argue.

But despite that progress, the ACA's future remains uncertain for two main reasons.

First, the Supreme Court earlier this year announced that it will hear a case seeking to overturn the ACA in its entirety. The lawsuit puts millions' of Americans' health coverage at risk, as well as the law's value-based payment reforms.

Second, increasing calls and support for transitioning the United States to a single-payer health system could render the ACA moot, though uncertainty over who will be in the White House and which party will control the House and Senate next year make the likelihood of such a major transition taking place anytime soon pretty small.

Regardless of what the future holds for the ACA, Kathleen Sebelius, who was serving as the nation's HHS secretary when the ACA became law, during an interview with Kaiser Health News' Julia Rovner said the law marks "a very positive step forward" for the United States' health care system. She explained, "I get stopped every day. I get stopped on airplanes and in grocery stores. And the stories are always very personal. People say to me, aren't you that health lady? My husband lost his job and we had to buy coverage in the market. And then he could get surgery. And because of you, we could get that coverage. They are breathtaking and heartbreaking stories where people say [their lives are] very different" because of the ACA.