In pursuing health care reform, the 2010 federal law popularly known as ObamaCare focused on boosting the number of people with health insurance. Michael Barone‘s latest column asks an interesting question that ought to have been addressed before Congress approved the federal health law.

Does having health insurance make people healthier? It’s widely assumed that it does. Obamacare’s advocates repeatedly said that its expansion of Medicaid would save thousands of lives a year. Obamacare critics seldom challenged the idea that increased insurance coverage would improve at least some people’s health.

Now, out of Oregon, comes a study that casts doubt on the premise that insurance improves health. …

… Comparing three important measures – levels of blood sugar, blood pressure, and cholesterol — [the Oregon Health Study] found no significant difference after two years between those on Medicaid and those who were uninsured.

It did find lower levels of reported depression among the group on Medicaid. And it found, unsurprisingly, that they did save significant money. Those findings may not be unrelated.

The findings have serious implications for Obamacare: Half of its predicted increase in insurance coverage comes from expansion of Medicaid. Obamacare supporters have assumed that those eligible for Medicaid — poorer, sicker, and less steady in habits than the general population — would have great difficulty getting health care without insurance. The Oregon Health Study is evidence that, at least in that state, Medicaid-eligible people without insurance — a “pretty sick” population, one state official said — nevertheless managed somehow to get care that produced results about as good as those who won the lottery.