The debate over the Affordable Care Act's Medicaid expansion divides states into two broad categories -- those that expand their program and those that don't.
New research suggests we should talk more about a third group: States that agree to expand Medicaid, then impose premiums whose only purpose seems to be keeping people out of the program.
A paper released Monday in the journal Health Affairs -- written by researchers from the federal government's Agency for Healthcare Research and Quality -- seeks to quantify the effect of premium increases on children's enrollment in Medicaid or its sister plan, the Children's Health Insurance Program. They found that even small premiums lead to big drops in sign-ups.
Using data from 1999-2010, the researchers -- Salam Abdus, Julie Hudson, Steven C. Hill and Thomas M. Selden -- found that for children in families making from 101 percent to 150 percent of the federal poverty line, a $10 increase in monthly premiums was associated with a 6.7 percent reduction in enrollment.
For the subset of families not eligible for health coverage through their jobs, that grew to 7.3 percent.
The authors of the Health Affairs study don't examine the effect of premium increases on adults. But Laura Dague, a professor at Texas A&M University, has.
In an article published in the Journal of Health Economics in May, Dague looked at three years of data from the Wisconsin BadgerCare Plus program, which offers subsidized health coverage to families with low incomes.
She found that moving from $0 to $10 a month reduced enrollment among children and adults by 12 percent to 15 percent.
What struck Dague about those results was that it's not just the magnitude of the premium that matters, but the existence of a premium.
"The biggest effects in my data were at the margin where folks start having to pay premiums at all," she told me by phone last week. She wasn't sure why that was -- perhaps the difficulty of paying another monthly bill or the psychology of having to pay in the first place.
What makes these papers relevant is that at least four states -- Indiana, Iowa, Michigan and Pennsylvania -- have expanded or are trying to expand Medicaid access in a way that imposes premiums on those making from 101 percent to 138 percent of poverty.
Those premiums aren't high: $25 a month in Indiana, $10 in Iowa, $25 in Pennsylvania ($35 for a household) and 2 percent of income in Michigan. But these new studies show that even those small amounts can significantly reduce the number of people who sign up.
That seems to be the point. After all, Medicaid spending per beneficiary will reach almost $6,400 in 2014, against which $120 in premiums each year generates additional revenue that's barely significant. And as Dague notes, imposing a premium at all means spending money to obtain and process those payments.
"If the administrative costs of collecting premiums are high relative to revenue collected," she wrote, "small premiums seem difficult to justify as anything other than a measure to discourage enrollment."
If the states that have already imposed premiums were the outliers, then this would be a frustrating story but a limited one.
However, 24 states still refuse to expand their Medicaid programs, and there's a strong chance that some of those will change their minds on the condition that they can impose premiums, too.
There's an equally good chance that the Centers for Medicare and Medicaid Services, which faces pressure to bring those states into the fold, will go along with it.
Unquestionably, access to Medicaid for a small premium is better than no access at all.
But this new research says we shouldn't mince words about the point of those premiums. They're designed to get fewer people to sign up.