As Congress debates changes to Medicaid and the Affordable Care Act, researchers studying two decades of health reform say the evidence points to several clear lessons: expanding coverage works, small barriers can keep eligible people from enrolling, and health insurance saves lives.
Those were the key takeaways from a recent webinar hosted by the Institute for Research on Poverty, where economists and policy researchers reflected on what policymakers have learned from Massachusetts' landmark 2006 health reform—the blueprint for many provisions of the ACA—and the decade-plus of evidence that has followed.
The biggest lesson, according to Harvard Kennedy School economist Mark Shepard, is that incremental reforms can dramatically reduce the number of uninsured Americans without overhauling the nation's employer-based insurance system.
"The Massachusetts model really does work to get uninsurance quite low," Shepard said, noting that the state's uninsured rate has fallen to just 2.8 percent—the lowest in the nation. While no system is perfect, he said, the experience demonstrates that policymakers can fill gaps in coverage through targeted reforms rather than replacing the existing insurance framework.
Just as important are the design choices that make those reforms successful.
Massachusetts paired insurance market reforms with generous premium subsidies and a streamlined enrollment process. Those decisions mattered. Shepard's research found that relatively small increases in premiums—or even modest paperwork requirements—can significantly reduce enrollment among low- and moderate-income households.
"If you just increase premiums by around $40 a month," he said, "about 25 percent of people drop out" among lower-income participants. Likewise, adding a single administrative step during enrollment reduced participation by roughly one-third and lowered annual retention by about 15 percent.
Those findings carry particular significance today as states prepare to implement new Medicaid eligibility checks and work requirements under recently enacted federal legislation.
"Small coverage barriers really matter," Shepard said, arguing that seemingly minor administrative changes can have outsized consequences for coverage, especially among younger and healthier adults who are more sensitive to paperwork and costs.
Affordability emerged as another central lesson.
Massachusetts supplemented federal ACA subsidies with additional state assistance, allowing many residents to obtain comprehensive coverage at little or no cost. Shepard argued that keeping premiums low helped attract healthier enrollees into the insurance pool, reducing premiums for everyone while maintaining a stable marketplace.
"The secret sauce," he said, is simple: "Make it affordable, make it easy."
While expanding coverage has proven achievable, controlling healthcare costs has been much more difficult.
Shepard noted that Massachusetts intentionally separated those goals, first expanding insurance and only later adopting measures aimed at slowing healthcare spending. Although the state has had some success in moderating cost growth, he acknowledged that "costs are very much harder than coverage."
Perhaps the strongest evidence presented during the webinar came from University of Chicago economist Angela Wyse, whose new research examined Medicaid expansion's impact on mortality using records from 37 million low-income adults.
Previous studies had consistently shown that Medicaid expansion increased insurance coverage and improved access to care, but questions remained about whether it measurably improved health outcomes.
Wyse's findings provide one of the clearest answers to date.
Her research estimates that adults who gained Medicaid coverage experienced roughly a 20 percent reduction in their risk of death. Nationwide, Medicaid expansions are estimated to have saved more than 27,000 lives between 2010 and 2022, while states that declined to expand Medicaid likely experienced thousands of avoidable deaths.
The findings also suggest Medicaid expansion compares favorably with many other accepted public health investments when measured by cost per life-year saved.
As moderator Dan Sacks, the Leslie P. Schultz Associate Professor in Risk Management and Insurance in the Wisconsin School of Business, summarized, "Policy can indeed increase health insurance coverage." Equally important, he said, the accumulated evidence now demonstrates that "health insurance coverage improves health."
The discussion concluded with one final lesson that extends beyond Massachusetts.
Even in states with near-universal eligibility, many people remain uninsured because they never complete the enrollment process. The remaining challenge, Shepard argued, is no longer simply making people eligible for coverage.
"The Obamacare law is a framework for universal eligibility," he said. "It's not a framework for universal automatic coverage."