John C. Goodman on Tuesday in a Wall Street Journal Op Ed models the potential problem of providing health insurance to people if the supply of doctors are constrained he figures that if more people have health insurance then more people will see the doctors causing longer wait times. This is particularly a problem in emergency situations as he writes
"When people cannot find a primary-care physician who will see them in a reasonable length of time, all too often they go to hospital emergency rooms. Yet a 2007 study of California in the Annals of Emergency Medicine showed that up to 20% of the patients who entered an emergency room left without ever seeing a doctor, because they got tired of waiting. Be prepared for that situation to get worse."
The question is did ER visits go up, and the answer from a recent paper by Sarah Miller forthcoming in the Journal of Public Economics (her paper can be found here) shows that actually the data indicate that the health care reform in Massachusetts decreased ER visits by 5-8% and particularly decreased non-emergency visits.
A little about the study from a quick read. One initial way to do such a study would be to compare ER visits in the years or months just before and after the reform. This would be a good first pass, but not convincing enough, because if we see that ER visits were higher in 2005 the year before the reform than say 2006 it might be from other causes than the reform (weather, the economy, the Red Sox's Bullpen?). So what Miller does is look at how rates of people in each county who were uninsured in 2005 influence influence ER visits in that year and future years. In 2005 before the reform the rate of people uninsured does not influence the rate of ER visits. After the reform the 2005 uninsured rate is negatively related to ER visits in years after the reform. This is good evidence since the reforms was likely to have a bigger influence in places with more uninsured people.
I don't want you to reach the conclusion that health insurance reduces health care or doctor use, since other research on a program in Oregon suggests that people use more health care when they have insurance. I did want to point out though I learned all of this by following different economists on twitter.