The Oregon Health Insurance Experiment

Treatment group: 29,834 people and 24,912 households selected in the lottery (the lottery winners)
Control group: 45,088 and 41,473 households not selected (the control group).

Adults randomly selected in the lottery were given the option to apply for Medicaid (specifically Oregon Health Plan Standard).Oregon Health Plan Standard provides comprehensive medical benefits, including prescription drugs, with no patient cost-sharing and low monthly premiums ($0 to $20, based on income), mostly through managed-care organizations.

2008-03-10

2013-12-31

health care use, health, financial strain

In early 2008, Oregon opened a waiting list for its Medicaid program for low-income adults that had previously been closed to new enrollment. Approximately 90,000 people signed up for the available 10,000 openings. The state drew names from this waiting list by lottery to fill the openings. Persons who were selected won the opportunity — for themselves and any household member — to apply for Oregon Health Plan Standard and were sent an application. Those who sent back their application and met eligibility requirements were enrolled in Oregon Health Plan Standard. This random selection allows researchers to gauge the causal effects of Medicaid. The study compiles rich data from many sources to examine a wide range of potential effects of insurance. Data include mail surveys, in-person interviews and health exams, and administrative data such as hospital records.

In 2008, the state of Oregon drew names by lottery. Randomization was done on state computer.

Household

Yes

66,385 households

74,922 people

Treatment= 29,834 people and 24,912 households Control= 45,088 people and 41,473 households.

Effect on Disease Management Analysis Plan - 2019-04-05

The Short-Run Impact of Extending Public Health Insurance to Low-Income Adults: Evidence from the First Year of The Oregon Medicaid Experiment - Analysis Plan 2010-12-01

Dental Care Analysis Plan - 2014-11-17

Depression and the Impact of Medicaid Analysis Plan - 2014-12-15

Criminal Charges Analysis Plan - 2014-04-30

Evidence from the In-person Interviews Analysis Plan - 2012-04-16

Evidence from Emergency Department Data Analysis Plan - 2013-03-06

Effect on Medications Analysis Plan - 2015-07-15

Evidence From Voting Data Analysis Plan - 2015-09-23

In 2008, Oregon initiated a limited expansion of a Medicaid program for uninsured, low-income adults, drawing names from a waiting list by lottery. This lottery created a rare opportunity to study the effects of Medicaid coverage using a randomized controlled design. Using the randomization provided by the lottery and emergency department records from Portland-area hospitals, we study the emergency department use of about 25,000 lottery participants over approximately 18 months after the lottery. We find that Medicaid coverage significantly increases overall emergency use by 0.41 visits per person, or 40 percent relative to an average of 1.02 visits per person in the control group. We find increases in emergency department visits across a broad range of types of visits, conditions, and subgroups, including increases in visits for conditions that may be most readily treatable in primary care settings.

Sarah Taubman, Heidi Allen, Bill Wright, Katherine Baicker, Amy Finkelstein, and the Oregon Health Study Group, "Medicaid Increases Emergency Department Use: Evidence from Oregon's Health Insurance Experiment", Science, 2014 Jan 17; 343(6168): 263-268.

http://www.sciencemag.org/content/343/6168/263.full.pdf?keytype=ref&siteid=sci&ijkey=GoMYHyTTSQ4.Q

In 2008, a group of uninsured low-income adults in Oregon was selected by lottery for the chance to apply for Medicaid. We use this randomized design and 2009 administrative data to evaluate the effect of Medicaid on labor market outcomes and participation in other social safety net programs. We find no significant effect of Medicaid on employment or earnings: our 95 percent confidence intervals allow us to reject that Medicaid causes a decline in employment of more than 4.4 percentage points, or an increase of more than 1.2 percentage points. We find that Medicaid increases receipt of food stamps, but has little, if any, impact on receipt of other government benefits, including SSDI.

Baicker, Katherine, Amy Finkelstein, Jae Song, and Sarah Taubman, "The Impact of Medicaid on Labor Force Activity and Program Participation: Evidence from the Oregon Health Insurance Experiment", NBER Working Paper 19547, October 2013.

http://www.nber.org/oregon/files/oregon_hie_LF_WP.pdf

Despite imminent expansion of Medicaid to low-income adults, the effects of expanding coverage are unclear. Oregon’s 2008 Medicaid expansion using lottery drawings from a waiting list provides an opportunity to evaluate the effects of Medicaid using random assignment. Approximately two years after the lottery, we collected data from 6,387 adults randomly selected to be able to apply for Medicaid coverage and 5,842 not selected. Measures included blood pressure, cholesterol and glycosylated hemoglobin; a depression screen; medication catalogs; and self-reported diagnoses, health, health care utilization and out-of-pocket spending. We use the lottery’s random assignment to calculate the effect of Medicaid coverage.We found no statistically significant effect of Medicaid on the prevalence, diagnosis, or medication of hypertension or high cholesterol. Medicaid coverage significantly increased the diagnosis of diabetes and use of diabetes medication, but we observed no significant effect on average glycosylated hemoglobin levels nor on the percent with levels >6.5%. Medicaid coverage decreased the probability of screening positive for depression (-9.15 percentage points; 95% CI: -16.70 to -1.60; P=0.018), increased use of preventive services, and almost eliminated catastrophic out-of-pocket medical expenditures. Thus, evidence using a randomized controlled design showed that Medicaid coverage generated no statistically significant improvements in measured physical health outcomes in the first two years, but did generate increased health care use, higher rates of diabetes detection and management, lower rates of depression, and lower financial strain.

Katherine Baicker, Sarah Taubman, Heidi Allen, Mira Bernstein, Jonathan Gruber, Joseph P. Newhouse, Eric Schneider, Bill Wright, Alan Zaslavsky, Amy Finkelstein, and the Oregon Health Study Group, "The Oregon Experiment – Effects of Medicaid on Clinical Outcomes" New England Journal of Medicine, 2013 May; 368(18): 1713-1722.

http://www.nejm.org/doi/full/10.1056/NEJMsa1212321

In 2008, a group of uninsured low-income adults in Oregon was selected by lottery to be given the chance to apply for Medicaid. This lottery provides an opportunity to gauge the effects of expanding access to public health insurance on the health care use, financial strain, and health of low-income adults using a randomized controlled design. In the year after random assignment, the treatment group selected by the lottery was about 25 percentage points more likely to have insurance than the control group that was not selected. We find that in this first year, the treatment group had substantively and statistically significantly higher health care utilization (including primary and preventive care as well as hospitalizations), lower out-of-pocket medical expenditures and medical debt (including fewer bills sent to collection), and better self-reported physical and mental health than the control group.

Amy Finkelstein, Sarah Taubman, Bill Wright, Mira Bernstein, Jonathan Gruber, Joseph P. Newhouse, Heidi Allen, Katherine Baicker, and the Oregon Health Study Group, "The Oregon Health Insurance Experiment: Evidence from the First Year" Quarterly Journal of Economics, 2012 Aug; 127(3): 1057-1106.

http://qje.oxfordjournals.org/content/127/3/1057