The Oregon Health Insurance Experiment: Evidence from the First Year*

Abstract

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.

Inclusion of quasi-experimental studies in systematic reviews of health systems research

“…Natural experiments may include investigations of the effects of policies implemented with a lottery system. For example, Baicker et al recently investigated the effect of the United States' Medicaid insurance program on use of health services, health spending, and clinical outcomes using exogenous variation in program enrollment produced when the Oregon state legislature assigned citizens to program eligibility using a random lottery [46,47]. In most respects, the analysis of data from natural experiments may be identical to the analysis of data from researcher-controlled experiments.…”

Does US health reform reduce hospital readmission rates?

“…Compared with the control group, lottery winners also reported that they were more likely to have a usual doctor, and they had more visits to doctors' offices, prescriptions, and recommended preventive care. 4 Medicaid was associated with improvements in self reported health status and depression, though findings for more objective measures of health (such as cholesterol level) were ambiguous or neutral. 6 However, Medicaid patients experienced around 40% more emergency department visits per person than did the controls.…”

“…1 This finding was similar to the Oregon experiment, which found no impact on readmissions. 4 Previous studies in Massachusetts have reported increases in utilization of preventive care after reform, 10 more patients having usual places of care, 10 improvements in self reported health status, 11 and increases in emergency department visits. 12 It is hard to generalize from these studies to the effect of the Affordable Care Act, as the context and populations are so different.…”

“…A few investigators have had the opportunity to do so using randomized controlled trials. [3][4][5] The RAND Health Insurance Experiment of the mid-1970s recruited more than 2000 households and found that higher co-payments within insurance products reduced resource use without large impacts on health or quality of care for most people. 3 For the poorest and sickest patients, however, the reduction in utilization associated with co-payments was harmful on average.…”

“…4 Policy makers chose random lottery as the fairest way to allocate the approximately 10 000 available places to those on the waiting list. Although unconventional, this policy resulted in an important opportunity to study the impact of Medicaid.…”