title: Does medication adherence lower Medicare spending among beneficiaries with diabetes?
abstract: OBJECTIVE
  To measure 3-year medication possession ratios (MPRs) for renin-angiotensin-aldosterone system (RAAS) inhibitors and statins for Medicare beneficiaries with diabetes, and to assess whether better adherence is associated with lower spending on traditional Medicare services controlling for biases common to previous adherence studies.
  
  
  METHODS
  Medicare Current Beneficiary Survey data from 1997 to 2005.
  
  
  METHODS
  Longitudinal study of RAAS-inhibitor and statin utilization over 3 years.
  
  
  METHODS
  The relationship between MPR and Medicare costs was tested in multivariate models with extensive behavioral variables to control for indication bias and healthy adherer bias.
  
  
  RESULTS
  Over 3 years, median MPR values were 0.88 for RAAS-I users and 0.77 for statin users. Higher adherence was strongly associated with lower Medicare spending in the multivariate analysis. A 10 percentage point increase in statin MPR was associated with U.S.$832 lower Medicare spending (SE=219; p<.01). A 10 percentage point increase in MPR for RAAS-Is was associated with U.S.$285 lower Medicare costs (SE=114; p<.05).
  
  
  CONCLUSIONS
  Higher adherence with RAAS-Is and statins by Medicare beneficiaries with diabetes results in lower cumulative Medicare spending over 3 years. At the margin, Medicare savings exceed the cost of the drugs.
authors.affiliation: Epidemiology and Public Health, School of Medicine, University of Maryland-Baltimore and Baltimore County, 660 W. Redwood St., Baltimore, MD 21201, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Stuart
authors.forename: Amy
authors.initials: A
authors.lastname: Davidoff
authors.forename: Ruth
authors.initials: R
authors.lastname: Lopert
authors.forename: Thomas
authors.initials: T
authors.lastname: Shaffer
authors.forename: J
authors.initials: J
authors.lastname: Samantha Shoemaker
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lloyd
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000191:economics / Q000627:therapeutic use*; D015897:Comorbidity; D003365:Costs and Cost Analysis; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000191:economics* / Q000628:therapy; D004363:Drug Utilization; D005260:Female; D015438:Health Behavior; D007722:Health Knowledge, Attitudes, Practice; D006304:Health Status; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage / Q000191:economics / Q000627:therapeutic use*; D007345:Insurance Claim Review / Q000706:statistics & numerical data; D008297:Male; D006278:Medicare / Q000191:economics*; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012737:Sex Factors; D012959:Socioeconomic Factors; D014481:United States; D016903:Drug Monitoring
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors