Secretive reviews target 30 Medicare Advantage plans

After years of criticism that they cost taxpayers too much, private Medicare Advantage health plans are facing landmark audits that for the first time could order them to repay the government tens of millions of dollars for past overcharges and other billing mistakes. Medicare pays the health plans a set amount monthly for each person based on estimates — known as "risk scores" — of how sick they are. The industry has grown explosively over the past decade under this payment method and now cares for nearly 16 million people at a cost expected to top $150 billion this year.