title: Researchers cite five major challenges facing Medicare Advantage plans.
mesh_terms: D017047:Cost Sharing; D005249:Fees and Charges / Q000639:trends; D006279:Health Maintenance Organizations; D006278:Medicare / Q000191:economics / Q000458:organization & administration*; D009937:Organizational Objectives; D012051:Reimbursement Mechanisms; D012108:Research Personnel; D014481:United States