Additionally, the authors add: “Most important, our quasi-experimental approach cannot definitively demonstrate a causal relationship underlying the association between the Massachusetts reform and the state’s declining mortality relative to other states. It is possible that the postreform reduction in mortality in Massachusetts was due to other factors that differentially affected Massachusetts, such as the recession. ”

There is more uncertainty as to whether the results of the study can be applied more broadly to Obamacare. The authors note that the study does provide “suggestive evidence” that the national health care law will have an impact on mortality. “However,” the authors add, “it is critical to note the many dimensions in which Massachusetts differs from the rest of the nation, including lower mortality, higher income and baseline insurance coverage rates, fewer minorities, and the most per capita physicians in the country. The extent to which our results generalize to the United States as a whole is therefore unclear, which underscores the need to monitor closely the Affordable Care Act’s effect on coverage, access, and population health across all states.”

Thus, it will take many future studies of the implementation of Obamacare to determine whether the nation as a whole can achieve the type of reduction in mortality that the authors detected in Massachusetts.