The myth of the University of Virginia "Medicaid is worse than nothing" study: or, why you should ignore Medicaid bashers.

In my last post on Medicaid expansion, I mentioned the claim, frequently made by opponents of Medicaid expansion, that Medicaid doesn't improve health outcomes. In this post I will look at one of the more negative versions of this claim: that it actually leads to worse health outcomes. Examples of this claim being made abound, such as this little nugget from the right-wing Galen Institute: "Mountains of clinical literature show that patients on Medicaid have, on average, poorer access to care and poorer health outcomes than those with no insurance at all. The largest national study, conducted by the University of Virginia, examined outcomes for 893,658 individuals undergoing major surgical operations from 2003 to 2007. It found that patients on Medicaid were 13 percent more likely to die in the hospital after surgery than those with no insurance, even when adjusting for age, gender, income, region, and health status. Medicaid patients were 97 percent more likely to die than those with private insurance."
There are innumerable instances of conservatives uttering variations of this claim, whether it's Florida senator Richard Corcoran, Virginia lieutenant gubernatorial candidate Pete Snyder, or Tim Phillips at Townhall.com. So what is this "University of Virginia study" and does it say what these politicians and pundits claim?
The answer to the first question is: "Primary Payer Status Affects Mortality for Major Surgical Operations", published in 2010 in the Annals of Surgery. As for the second question, the study states that "Unadjusted mortality for Medicare (4.4%; odds ratio [OR], 3.51), Medicaid (3.7%; OR, 2.86), and Uninsured (3.2%; OR, 2.51) patient groups were higher compared to Private Insurance groups (1.3%, P < 0.001)." This basically means that people on Medicare, Medicaid, and no insurance, were, respectively, 3.51, 2.86, and 2.51 times more likely to die than were people on private insurance. Divide 2.86 by 2.51 and you get about 1.14 (if you round up), which means according to this study, people on Medicaid were 14% more likely to die than uninsured people. Right? 
Well, yes, but this doesn't mean Medicaid was totally or even partly the reason for this pattern. As Politifact has put it, "Medicaid recipients are the poorest, sickest and least educated group of patients. They are the least likely group to seek preventive health care. As a result, they are more likely to enter hospitals in dire conditions that require emergency surgery.

"Medicaid patients had the highest incidence of acquired immunodeficiency syndrome, depression, liver disease, neurologic disorders and psychoses," the study said. "Furthermore, Medicaid patients had the highest incidence of metastatic cancer." In other words, to quote Irving Kron, another co-author of the study, "The reality is it’s apples and oranges. The problem with Medicaid is there’s more emergencies, because they’re sicker than most people. … They wait for care and unfortunately, emergent patients don’t do as well as elective patients." So this confounding factor could account for the reason Medicaid patients did worse than uninsured ones, rather than Medicaid being an inferior system.

The researchers behind the study have also said that "uninsured patients have similar characteristics to Medicaid recipients and that it is "plausible" that both groups may suffer from a "system bias" that limits their access to private hospitals and top physicians." 

If you don't find these arguments compelling, consider that there are other possible confounders that may well explain a lot of the mortality differences found in this study: "Not all of the uninsured patients in the study were low-income people who would qualify for Medicaid if it is expanded. Thirty-one percent of them lived in zip codes where the average household income was greater than $45,000. Many of these people may have been uninsured by choice. "The uninsured population in our study included a subgroup that may have had a high income," Ailawadi [one of the study's authors] said." Also worth noting is that Ailawadi has also said that "I don’t think we’re able to say a government-sponsored system is beneficial or not." If he, one of the study's authors, doesn't believe his study proves which type of insurance is the best in terms of health, then who are politicians, pundits, and other non-experts to suggest otherwise?  Similarly to the above confounders, other experts have noted that "...uninsured patients may elect to go without coverage and end up on Medicaid when they become sick, or that insured patients in the study may have reached lifetime policy limits and had to resort to Medicaid."

And as though this all weren't enough to debunk the right-wing interpretation of this study, consider that it wasn't even supposed to study which system worked better! Kron himself has said that the study he co-authored "focused on whether socioeconomic status was a factor in medical treatment, which it clearly was, and not on the quality of the systems paying for health care."

In short, don't believe this bullshit about the "13 percent worse" claim about Medicaid, which totally 

misses the point of the study on which it is based and lots of other factors that could account for this 

difference.