1. Medicare Part B: Medicare represented at least half of the market for 22 of the 84 most expensive drugs in 2015 : report to Congressional requesters Publication: Washington, DC : United States Government Accountability Office, December 2017 Subject(s): Drug CostsHealth Care SectorHealth ExpendituresMedicare Part B -- economicsInsurance, Health, ReimbursementMedicare Part B -- statistics & numerical dataHumansUnited States