Although expanding Medicaid coverage to some low-income Oregon residents substantially improved their mental health and reduced financial strains on them, it didn’t significantly boost their physical health, according to a study published Wednesday in the New England Journal of Medicine.

Image by Darwinek via Wikimedia Commons

The findings are less upbeat than a preliminary report by the same group, which had found that Medicaid made a “big difference” in people’s lives. In the latest effort, researchers dug deeper. They compared health status, finances and use of health services between two groups of residents: some of the 10,000 people who had been selected through a lottery drawing for health insurance coverage under a 2008 limited expansion to Oregon’s Medicaid program and those who had applied but did not get accepted.

Based on analyses of 12,229 people – 6,387 of whom gained coverage – the study’s results did not show any significant difference in the levels of high blood pressure, high cholesterol and diabetes between the two groups two years after the lottery.

The study did find improvements in other categories, including mental health. Gaining access to Medicaid, for example, reduced depression by 30 percent and also increased participants’ use of physician services, prescription drugs and preventive care. It also led to increased detection of diabetes and use of medication to control it.

Those covered by Medicaid also had lower out-of-pocket spending, the researchers reported, including a 4.5 percentage point difference in catastrophic expenditures.

“We were able to provide a multifaceted picture of what happened when people gained insurance through Medicaid, versus those who did not,” said Dr. Katherine Baicker, the study’s lead author, in an interview.

Dr. Devon Herrick, senior fellow at the National Center for Policy Analysis, a nonpartisan research organization, said he was shocked to see so little data suggesting that Medicaid expansion improved overall health.

“It didn’t seem to affect the outcome of those with diabetes,” Herrick said in an interview. “It boosted their use of medication but didn’t seem to improve their health – that’s something we would all assume.”

“The results of this indicate that states can’t just expand Medicaid and as a result, suddenly improve the health of all those that enroll – it didn’t seem to work that way,” Herrick added.

According to the study, more than 90,000 state residents participated in Oregon’s Medicaid lottery. Researchers have used that group to study the impact of expanding health coverage. Although not designed to do this, Baicker said the two groups can be seen much like a randomized controlled trial that allows researchers to evaluate the effect of Medicaid on low-income adults.

“Expanding Medicaid costs money and there has to be a way to finance the program. It doesn’t save money but it substantially improves the wellbeing of beneficiaries, although maybe not in exactly the way some people might have thought,” Baicker said, adding that “policymakers have to decide whether that set of benefits is worth the cost of the program in terms of the alternative uses of the resources.”

The expansion of Medicaid, called for by the 2010 health care law, is being intensely debated in many states since the Supreme Court made that provision voluntary last year. Fifteen states, many in the Republican-controlled South, have already rejected the idea, while 20 have agreed to comply with the law, according to consulting firm Avalere Health.