Historically, hospitals have provided care for people, while separate insurers have paid for that care.

During the past two decades, however, this arrangement has changed. Today, nearly 1 in 3 hospitals also own insurance plans – putting them on both sides of the transaction.

Sometimes referred to as “payviders,” these hospitals decide when and how to provide treatment, but they also decide when and how much to pay for that treatment for people enrolled in their insurance plans. This arrangement raises an important question for patients, providers, policymakers and researchers like us: What happens when your hospital and insurer are owned by the same company?

As health services scholars who study policy, practice and economics, we are working to uncover what is good, bad and unknown about bringing hospitals under the same corporate roof as insurance companies. Our research focuses on Medicare Advantage, the private version of the traditional Medicare program administered by the federal government.

Health plans that are owned by hospitals have sprung up in many insurance markets, including commercial insurance, Medicaid – which is largely managed by states – and Medicare Advantage.

Medicare Advantage is the private alternative to the traditional Medicare program administered by the federal government. Medicare insures people 65 or older and some who are younger and disabled. The commercial Medicare Advantage option now accounts for the majority of Medicare enrollment, or just over 35 million people.

We and a colleague spent six months compiling a database of people who are insured through a Medicare Advantage company that is affiliated with a hospital.

We started with data from the Agency for Healthcare Research and Quality, where hospitals can report whether they offer a Medicare Advantage plan. We then searched hospital websites, press releases and news articles to find the identity of each plan. We also checked through the list........

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