A new study suggests that, rather than reducing the number of emergency room visits, possessing health insurance actually led to an increase in the number of visits people made. From The New York Times:

The study, published in the journal Science, compared thousands of low-income people in the Portland area who were randomly selected in a 2008 lottery to get Medicaid coverage with people who entered the lottery but remained uninsured. Those who gained coverage made 40 percent more visits to the emergency room than their uninsured counterparts during their first 18 months with insurance.

The pattern was so strong that it held true across most demographic groups, times of day and types of visits, including those for conditions that were treatable in primary care settings.

The study seems to dispute the claims of Affordable Care Act proponents who argued that owning a health insurance policy would actually lead to less emergency room or urgent care visits.  Back in September, the President remarked that insurance "is helping them because people are no longer going to the emergency room and they now have good health care, they’re now getting preventive care."

That wasn't the case in the Orgeon study, although as NPR notes, the study only observed a relatively short period of 18 months and the population studied was more white and urban than other areas of the country.

But while ER visits rose in patients with Medicaid, so did primary care visits, meaning that more health coverage was being consumed across the board, not just one particular part of it. Additionally, earlier studies by the same authors did not uncover "any statistically significant improvements in how well the new Medicaid recipients managed their high blood pressure, cholesterol, or diabetes."

Granted, this is only one study about ER usage. Others, such as one published in the New England Journal of Medicine concerning Massachusetts healthcare, found no change in emergency care usage after the implementation of its healthcare reforms.