Insurers' Acquisition Of Ambulatory Surgery Centers Was Not Associated With Changes In Performance, 2013-21.

Vertical integration between insurers and providers is increasingly common in US health care markets, yet there is little evidence on its impacts. This study examined the association between UnitedHealthcare's acquisition of ambulatory surgery centers (ASCs) and performance and pricing for arthroscopy and colonoscopy procedures. Using 100 percent Medicare fee-for-service claims data from the period 2013-21, we applied a difference-in-differences approach to assess changes in ASC size, procedure volume, and quality of care, as well as patient mix. We analyzed 2023 data from the Transparency in Coverage initiative, using a propensity score-matching framework to compare negotiated facility fees between UnitedHealthcare and the three other largest commercial insurers in the US by enrollment: Blue Cross Blue Shield, Aetna, and Cigna. We found no changes in the number of providers or patients, procedure volume, or patient mix. There was a slight decline in the probability of complications after colonoscopy, beginning the second year after ownership change. UnitedHealthcare had significantly lower facility rates compared with other insurers, at ASCs that UnitedHealthcare did and did not own. As consolidation among insurers and ASCs increases in scope and attracts regulatory scrutiny, our study provides evidence to inform antitrust policy and enforcement activity.