Medicare prescription drug benefit variations.
D000368:Aged; D003625:Data Collection; D006279:Health Maintenance Organizations / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D007342:Insurance Benefits / Q000706:statistics & numerical data; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data*; D006278:Medicare / Q000706:statistics & numerical data*; D014481:United States