Medicare overpayments to private plans, 1985-2012: shifting seniors to private plans has already cost Medicare US$282.6 billion.

Previous research has documented Medicare overpayments to the private Medicare Advantage (MA) plans that compete with traditional fee-for-service Medicare. This research has assessed individual categories of overpayment for, at most, a few years. However, no study has calculated the total overpayments to private plans since the program's inception. Prior to 2004, selective enrollment of healthier seniors was the major source of excess payments. We estimate this has added US$41 billion to Medicare's costs since 1985. Medicare adopted a risk-adjustment scheme in 2004, but this has not curbed private plans' ability to game the payment system. This has added US$122.5 billion to Medicare's costs since 2004. Congress mandated increased payment to private plans in the 2003 Medicare Modernization Act, which was mitigated, to a degree, by the subsequent Affordable Care Act. In total, we find that Medicare has overpaid private insurers by US$282.6 billion since 1985. Risk adjustment does not work in for-profit MA plans, which have a financial incentive, the data, and the ingenuity to game whatever system Medicare devises. It is time to end Medicare's costly experiment with privatization. The U.S. needs to adopt a single-payer national health insurance program with effective methods for controlling costs.