Expert Commentary

Oregon health insurance experiment: Evidence from the first year

2012 study by MIT and Harvard on impacts of randomly assigned Medicaid insurance in Oregon on public health outcomes.

For researchers, it has often been difficult to conduct experimental studies on health care outcomes due to biases introduced by differences between insured and uninsured individuals. To produce unbiased data, the ideal circumstance would require the provision of health care to be randomly assigned across a population.

A 2012 study from the Massachusetts Institute of Technology and the Harvard School of Public Health, “The Oregon Health Insurance Experiment: Evidence from the First Year,” utilized Oregon’s 2008 decision to hold a randomized lottery for the provision of Medicaid insurance in order to measure the impact of health insurance on an individual’s health and well-being. Published in 2012 in The Quarterly Journal of Economics, the study examined the outcomes of the 10,000 lower-income people eligible for Medicaid who were chosen by this randomized system.

The study’s findings include:

  • Hospital utilization increased by 30% for those with insurance, with the length of hospital stays increasing by 20% and the number of procedures increasing by 45% for the population with insurance.
  • Medicaid recipients proved more likely to seek preventative care. Women were 60% more likely to have mammograms, and recipients overall were 20% more likely to have their cholesterol checked.
  • Those who had insurance had a 10% lowered chance of having an unpaid bill sent to a collection agency. For medical bills only, there was a 25% lowered chance of unpaid bills been sent to a collection agency.
  • In terms of self-reported health outcomes, having insurance was associated with an increased probability of reporting one’s health as “good,” “very good,” or “excellent” — overall, about 25% higher than the average.
  • Those with insurance were about 10% less likely to report a diagnosis of depression.

The researchers caution that, due to the relatively small sample size, their “estimates are therefore difficult to extrapolate to the likely effects of much larger health insurance expansions, in which there may well be supply side responses from the health care sector.”

Tags: campaign issue, health care reform, mental health