Crossing State Borders: The Interstate Medical Licensure Compact and Hospital Quality

Board-licensed health practitioners often face significant barriers to mobility across state borders, including requirements for new licenses at the state level. These requirements reduce mobility across state borders, including occupational mobility as well as residential mobility. These requirements may also impact the health care quality and access which patients face in their state, especially those patients who live in areas with low access to care, as the mix of physicians they face changes. The Interstate Medical Licensure Compact was launched to increase access to health care for patients, but it also impacts the ability of physicians to practice across state lines. In particular, it facilitates the ability of physicians to obtain licenses to practice in multiple states, and in some cases, states will grant licenses based on the physician’s licenses obtained in other states. As more physicians can practice in more states, patients may face changes in the quality of their care, including infections, mortality, hospital readmissions, etc. We here consider the effect of the IMLC on the quality of care which patients receive in states which are part of the IMLC compared with those which are not. In order to measure quality, we use Hospital Compare data on Healthcare Associated Infections at the hospital level. We focus on data from 2012 to 2017, with the treatment year in 2015. Our sample consists of 4,388 hospitals and 429,732 total observations. We then link the file of state and year indicators from the IMLC dataset with the Hospital Compare dataset on Healthcare Associated Infections. We then test the effect of interstate licensing on quality, as measured by scores for infections, using a difference-in-differences regression model with fixed effects. We also plan to run a secondary test on the effect of the type of licensure agreement on infection quality, as well as on physician mobility. Preliminary results indicate that hospitals which are located in states which are part of the IMLC have significantly lower infection levels than hospitals located in states which are not part of the IMLC, with an estimated interaction effect of -412.82 (105.09). We also plan to further include several robustness and specification tests, including using alternative measures for infections and quality.