Medicare Preservation and Anti-Privatization Act - Amends title XVIII (Medicare) of the Social Security Act (SSA), as added by the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, to eliminate the MA Regional Plan Stabilization Fund.
Directs the Secretary of Health and Human Services to provide, beginning with 2005, for adjustment of payment rates to Medicare+Choice organizations so that they reflect only the payment at 100 percent of the fee-for-service rate.
Provides that, in applying risk adjustment factors to payment to Medicare+Choice organizations in a budget neutral manner, the Secretary of Health and Human Services shall assure that such factors, in the aggregate, take into account the actual characteristics of the entire Medicare population, and not merely the population of individuals enrolled under a Medicare+Choice plan under part C (Medicare+Choice) of SSA title XVIII.