How Do We Know if ACA Expansion Worked?

The best available study found no improvements in mortality or any other physical health outcome from expanding Medicaid

Letter to the WSJ. 

"Angela Wyse and Bruce D. Meyer argue that their research shows ObamaCare’s Medicaid expansion reduced mortality among low-income able-bodied adults in states that implemented it (Letters, June 4). We hope they’re right. We hate to think Congress increased Medicaid spending by one third—ferrying more than $200 billion annually from bondholders to insurance companies—without saving a single life in the process.

Unfortunately, that may be the case. The best evidence on the health effects of the Medicaid expansion comes from the Oregon Health Insurance Experiment. The OHIE is a randomized controlled trial, or RCT—the gold standard for such research, and more reliable than Profs. Wyse and Meyer’s evaluation or any other non-RCT. The OHIE found no improvements in mortality or any other physical health outcome from expanding Medicaid. That was true among the most vulnerable members of the Medicaid-expansion population and for the measures amenable to medical care within the study’s timeframe.

The OHIE isn’t the final word, but it is the best word, in part because it is consistent with other randomized controlled trials showing that, at the margin, health insurance often has little or no effect on health. Profs. Wyse and Meyer conducted a sophisticated observational study. But such studies don’t establish causation with nearly as much reliability. Consider, for instance, that the available observational studies offer conflicting evidence. Several have found no effect of Medicaid expansions on mortality, while one suggests the expansion worsened mortality by fueling the opioid crisis in states that implemented it.

In complex systems, RCTs do a superior job of controlling other variables to illuminate the true effect of the variable of interest. They are less susceptible to spurious results and cherry-picking to confirm one’s ideological priors.

Unfortunately, the question of Medicaid’s effects on health has only become more political as Congress reconsiders the program’s funding levels. We hope Profs. Wyse and Meyer will join us in acknowledging the uncertainty surrounding this question and join our call for the only type of research that can dispel it: further, larger and longer RCTs of the effects of Medicaid on health outcomes.

Brian Blase and Michael F. Cannon

Paragon Health Institute and
Cato Institute"