What’s the value of Medicaid? Read Chris Conover

I recently discussed how the expansion of Medicaid through the ACA may benefit people living with HIV/AIDS. Specifically, getting insurance may encourage previously uninsured people at risk to get tested. Some of them will discover that they are HIV+, enabling them to benefit from early combined antiretroviral treatment (cART). If so, they will not only greatly extend their own lives, but also prevent significant numbers of fresh HIV infections, because cART radically reduces the probability of sexual transmission of HIV.

This is a plausible argument for one benefit of expanding Medicaid. But plausible arguments are one thing, confirmatory data are another. A critic can and should ask: If expanding Medicaid really saves lives, why don’t we have data supporting a strong mortality benefit for people receiving Medicaid versus being uninsured?

Chris Conover has a thoughtful post on just this question. He makes two valuable points. First, he questions some previous research that purported to show a large mortality cost of being uninsured. Second, he poses a nifty thought experiment designed to raise questions about whether expanding Medicaid is a cost-effective way to increase life expectancy.

Conover begins by reviewing some claims for dramatic mortality benefits associated with becoming insured, based on observational studies (such as this one). He demolishes these claims, for reasons that are worth quoting.

All are so-called observational studies meaning that the two groups being compared (uninsured and privately insured) each self-selected itself into the group. Many uninsured admittedly are in that group because they lack the means to pay for coverage, but the key point here is that unlike a randomized controlled trial, in which people are randomly assigned to be in either the “treatment” group or “control” group, there is no reason to suppose that the characteristics of the two groups will be comparable.

This argument also demolishes the commonly heard claim that Medicaid is harmful compared to being uninsured. This claim is similarly based on observational studies that are methodologically weak for causal inference purposes, studies that Conover sensibly ignores.

Unfortunately, Conover does not discuss the most relevant scientific studies on the effects of getting health insurance (like this one). This is the instrumental variables literature, summarized by Austin here. In these studies, researchers look at ‘experiments of nature,’ where large groups of people received or did not receive Medicaid for arbitrary reasons that mimic random assignment. Austin:

My take-away from the Medicaid-[Instrumental Variable] literature review is: there is no credible evidence that Medicaid results in worse or equivalent health outcomes as being uninsured. […] [It] strongly suggests Medicaid is better for health than no insurance at all.

This conclusion was reprised in the NEJM by Austin, Aaron, Harold Pollack, and Uwe Reinhardt.

So what’s my bottom line on the mortality benefit of Medicaid? Getting Medicaid will likely give the average uninsured person at best a small mortality benefit, albeit of uncertain amount. It likely gives the small group of uninsured people with dire health conditions — e.g., people living with HIV/AIDS — a larger benefit. (And, although this is a different question, we could build a better insurance program for the poor than Medicaid, and it would likely have a better effect.)

Conover, however, then poses a challenge to people who hold views like mine. He notes that there are preventive health interventions targeting smokers that would save lives with greater certainty than expanding Medicaid. So if we are interested in reducing mortality — and if the health benefit of Medicaid is likely small — then is increasing Medicaid the most cost-effective way to improve longevity?

It would be uncharitable to read Conover as literally proposing to repeal the Medicaid expansion and instead invest billions of dollars in preventive health care. This is, instead, a worthwhile thought experiment. Conover wants people who defend the Medicaid expansion to explain why given the small (possibly negligible in his view, but not mine) and uncertain (his view and mine) mortality benefit.

I have no trouble defending the expansion, in part because I have no need to do so on mortality benefits alone. Insurance has financial and quality of life benefits over and above its effect on mortality. And even though it may have only a small mortality benefit for the average uninsured person, it will mean life or death for others, and those people matter. For these reasons, people across the world view access to health care for all citizens as a matter of justice.

Moreover, I do not attribute the small benefit of Medicaid primarily to the deficiencies of that scheme for financing health care. Remember, what insurance does for health is to provide access to health care. My view is that the effect of insurance is much smaller than it should be, given the money that we spend on it, because the effect of accessing health care is much smaller than it should be, given the money that we spend on it. Universal access to health care is a solvable problem: check almost any developed country. Conover’s thought experiment ought to shock us into asking the harder and deeper question: “Why doesn’t our health care system give the poor and rich alike better value for our health care dollars?”

That question has many answers. Here are a few: We don’t pay enough attention to the social determinants of health. We don’t work hard enough to fix the manifold deficiencies in the quality of health care. We miss opportunities for cost-effective prevention. We don’t follow patients effectively, to support them in adhering to their treatments. And we don’t invest enough in medical research to achieve fundamental advances both in treatments and in how to deliver them.

Perhaps Conover sees the matter differently. Nevertheless, I urge you to think through the point highlighted by his thought experiment, that extending health insurance has only a small and uncertain effect on mortality. One thing that I hope we can all agree on is that our reaction to the literature on the effect of Medicaid on health should be: We can do better.


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