CMS underestimated Medicare ACOs' savings

The Medicare Shared Savings Program generated $1.84 billion in savings over three years, which is nearly twice the savings that CMS data show, according to a new study commissioned by the National Association of ACOs.

The study, published Tuesday, also found accountable care organizations reduced Medicare spending by $542 million after accounting for shared savings by the ACOs from 2013 to 2015. This contradicts data from the CMS that ACOs actually increased Medicare spending by $344 million over the time period. 

The study is the latest in a series that find Medicare ACOs are saving more money than CMS' methodology shows. Just last week the New England Journal of Medicine published an analysis with similar results. ACO analysts argue the CMS consistently underestimates savings because it's using a benchmarking methodology, which only compares ACO performance over the years to calculate savings.