Medicaid increases ER vists

The Times reports on a Science article finding strong increases in ER usage following the randomized Oregon Medicaid expansion, based on administrative data. Toward the bottom of the first page of the Science article, the authors conveniently summarize their other findings to date:

• Medicaid improved self-reported general health and reduced depression
• No statistically significant effects on measured physical health, specifically blood pressure, cholesterol, or glycated hemoglobin levels
• Medicaid decreased financial strain, but did not have statistically significant effects on employment or earnings
• Medicaid increased health care use; increased self-reported access to and use of primary care, as well as self-reported use of prescription drugs and preventive care
• No statistically significant effect of Medicaid on self-reported use of the hospital or the emergency department; however, Medicaid increased hospital use as measured in hospital administrative data

The authors discuss some reasons why patterns in self-reports, which didn't suggest many effects of the expansion, differ from those in administrative data. The latter are of higher precision and represent different universes. Administrative data pick up the behavior of people who don't respond to survey requests or who don't complete interviews.