Between2000 and 2012, the cost of inpatient hospital stays rose muchfaster for privately insured patients than Medicare enrollees.(Photo: Shutterstock)

A new analysis takes a look at the difference between whatprivate health plans and Medicare pay for hospital stays.

The analysis, published by Thomas M. Selden in Health Affairs, examines the cost of hospitalstays from 2000 to 2016.

Between 2000 and 2012, the cost of inpatient hospitalstays rose much faster for privately insured patients than Medicareenrollees. At the beginning of the millennium, private plans wereonly paying 10 percent more than Medicare, but that gap grew to 75percent by 2012.

Related: Hospital costs drive private health insurancespending

However, things changed in the subsequent four years. Privatepayments dropped sharply from 2012 to 2013 and were still lower in2016 than they had been four years prior.

Meanwhile, during that time, Medicare payments rose at a fasterrate than at any other point in the 21st century.

Thus, by 2016, private insurance payments were only 50 percentgreater than Medicare payments.

While Medicaid paid the least for hospital stays, it trajectorywas similar to private insurers: the average cost dropped in 2012and climbed slowly in the following years.

The trends were similar for emergency department visits. Thestudy analyzed emergency payments from a 20-year period, 1996-2016,and found that the average cost of an ER visit rose by roughly 50percent for a Medicare patient but by more than 100 percent for aprivately-insured patient.

Since 2005 the average Medicaid payment for an ER visit hasactually been slightly higher than Medicare, although it hasfollowed an almost identical trend.

The obvious major policy change that may have shaped theoutcomes from 2012 to 2016 is the Affordable Care Act, although theACA did not go into full effect until the end of 2013.

According to the authors, "more research is needed into not onlythe causes of rapid private insurance payment increases but alsothe consequences of those differences."

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