States with expanded Medicaid eligibility may be more vulnerable to adverse selection, hastening the death spiral of their Obamacare insurance exchanges relative to states without expanded Medicaid. This is because 1) the expanded, eligible Medicaid population is young, and 2) pricing (net of subsidies) and benefits on the exchanges encourage sicker individuals to purchase plans with richer benefits. The Political Calculations blog presents this case in “How Medicaid’s Expansion Tips the Scales Against Obamacare“:

“… we observe that the states that did not expand their Medicaid programs have a much larger share of their ACA-enrollment occurring in the lower-tier metal plans that would tend to be favored by healthier individuals. Meanwhile, in the states that expanded the enrollment of their Medicaid programs under the law, we find that a significantly larger portion of their ACA enrollments were in the plans that would be favored by less healthy individuals.

In fact, we see that in Medicaid expansion states, 13.2% of their ACA enrollment occurred in the highest-tier Gold and Platinum level plans, while non-Medicaid expansion states saw 7.7% of their enrollment for these highest tiers of health insurance coverage.

The seemingly small 5.5% difference between these two figures becomes exceptionally significant when you consider how extremely concentrated health care expenditures are in the United States, where just 5% of U.S. patients are responsible for generating 50% of all health care spending in the nation.“

It will be difficult to confirm this hypothesis using data on premium increases, or actual exchange failure, until the temporary risk corridors and transitional reinsurance program expire. However, this year, several of the states in which proposed premium increases are the largest have expanded Medicaid eligibility. Robert Laszewski has a good discussion about some the reasons for the large premium increases in Forbes. It’s early and there are signs that it will get worse.

As noted last week on this blog, Medicaid itself does not stack up well in terms of how highly it is valued by recipients and the moral hazard inherent in the program. Here we see an additional bug: expanded Medicaid appears to siphoning away younger potential enrollees from the exchanges in those states, worsening the problem of adverse selection, which will negatively affect their claims experience.