Does health insurance encourage the rise in medical prices? A test on balance billing in France

We evaluate the causal impact of an improvement in insurance coverage on patients' decisions to consult physicians whocharge more than the regulated fee. We use a French panel data set of 43,111 individuals observed from 2010 to 2012. Atthe beginning of the period, none of them were covered for balance billing; by the end, 3819 had switched to supplementaryinsurance contracts that cover balance billing. Using instrumental variables to deal with possible non-exogeneity of thedecision to switch, we find evidence that better coverage increases demand for specialists who charge high fees, therebycontributing to the rise in medical prices. People whose coverage improves increased their average amount of balancebilling per consultation by 32%. However, the impact of the coverage shock depends on the supply of physicians. Forpeople residing in areas where few specialists charge the regulated fee, better coverage increases not only prices but alsothe number of consultations, a finding that suggests that balance billing might limit access to care. Conversely, in areaswhere patients have a genuine choice between specialists who balance bill and those who do not, we find no evidence of aresponse to better coverage. Copyright © 2016 John Wiley & Sons, Ltd.