Via Austin Frakt at The Incidental Economist (I shortened the summaries):
Market Power: Recent NBER publications by Laurence Baker, M. Kate Bundorf, and Daniel Kessler:
We find that a hospital’s ownership of an admitting physician dramatically increases the probability that the physician’s patients will choose the owning hospital. We also find that ownership of an admitting physician has large effects on how the hospital’s cost and quality affect patients’ hospital choice. Patients whose admitting physician is not owned by a hospital are more likely to choose facilities that are low cost and high quality. ... We conclude that hospital/physician integration affects patients’ hospital choices in a way that is inconsistent with their best interests.
To what extent does the generosity of health insurance coverage facilitate the exercise of market power by producers of health services? […]
We find a statistically significant and economically important effect of plan generosity on hospital prices in uncompetitive markets. ...