A new working paper published in the National Bureau of Economic Research shows that the link between Medicaid expansion and improved rates of adult mortality is not as clear as previous research has suggested.

Titled “Revisiting the connection between state Medicaid expansions and adult mortality,” the paper reviewed data over a nine year period from eight states that have expanded Medicaid — Arizona, Illinois, Maine, Michigan, New Mexico, New York, Oregon, and Vermont. The lineup of states included those that had expanded Medicaid prior to the enactment of the Affordable Care Act expansions in 2014, plus those that had done so after that date.

“The main implication of our results, when combined with the prior literature, is that one should not assume that state Medicaid expansions automatically lead to reductions in adult mortality,” the authors concluded. “Instead, the effects of each expansion are likely dependent on a number of factors, such as the availability of services and providers for Medicaid enrollees, the demographic characteristics of the population, and other concurrent changes in the health care system.”

The authors noted that they stopped “short of claiming that our results show conclusively that Medicaid expansions do not have any effect on mortality at all. Rather, we argue merely that the evidence that pre-ACA Medicaid expansions to adults saved lives is not as clear as suggested by previous research.”

The working paper debunks recent research which found a positive correlation between Medicaid expansion and saving adult lives, including a 2021 study that found a 9.4% reduction in adult mortality in expansion states compared to non-expansion states.

“This latest study calls into question previous research that supposedly showed that Medicaid expansion saves lives,” noted Brian Balfour, senior vice president of research at the John Locke Foundation. “For advocates of expanding Medicaid in North Carolina, they’ve been insisting that blocking expansion has been costing lives. This latest study shows that such proclamations are not based on conclusive evidence.”

Medicaid expansion is expected to be a major issue in the upcoming long session of the North Carolina General Assembly. In June, the N.C. Senate passed a Medicaid expansion bill in a 44-2 vote that included a repeal of some certificate-of-need (or CON) laws and an expansion of practice of authority for nurses. The state House has been unwilling to tie CON reform to its own version of Medicaid expansion.

Reforming CON laws would ease the regulatory burden faced by new medical facilities, and experts argue that such reforms would increase the availability of medical services and lower costs.