Oregon Experiment

In a previous blog I promised to disclose the results of the Oregon experiment on the effects of providing health insurance to previously uninsured people. To recap, in the USA all young and middle-aged adults below the poverty line are provided with national insurance called Medicaid. The state of Oregon wished to extend such insurance to a category of slightly better-off people, yet did not have enough money to provide insurance for all in this category. Eligibility was therefore determined by lottery, on the grounds that this would be a fair way to distribute a scarce resource – a reverse of the draft if you like. Of course, such distributional exercises constitute an unintended RCT if one can find out who was randomised to which condition and then follow them up. Baicker et al. did just that.[1] The results are politically sensitive (as you will see if you search the internet), but wisely the authors published the protocol before analysing the data.

The results show that the group offered insurance sought more services, engaged in more preventive activities, had lower expenses, and were more likely to avoid catastrophic payments than those not offered cover. There was no difference between groups in proportions with high blood pressure or elevated glycosylated haemoglobin and death rates did not differ (under 1% in both groups). Patients offered insurance were more likely than those not selected in the lottery to report improved health and the mental component of the quality of life score was improved.

Only two year follow-up data are available. A health economic analysis was not attempted. Despite the study size (over 12,000 people), the power to detect changes in rates of diseases, such as diabetes and hypertension, was low. What is not in doubt is that insurance relieves financial stress and the anxiety that goes with it. This study is relevant for two reasons. First, the results are of policy relevance world-wide. Second, it is a fine example of a high quality academic output from an entirely service-led intervention. Indeed, it conforms with the CLAHRC model, where the service dog wags the research tail.

— Richard Lilford, CLAHRC WM Director


  1. Baicker K, Taubman SL, Allen HL, et al. The Oregon Experiment – Effects of Medicaid on Clinical Outcomes. N Engl J Med. 2013; 368: 1713-22.

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