title: How Medicare Part D benefit phases affect adherence with evidence-based medications following acute myocardial infarction.
abstract: OBJECTIVE
  Assess impact of Medicare Part D benefit phases on adherence with evidence-based medications after hospitalization for an acute myocardial infarction.
  
  
  METHODS
  Random 5 percent sample of Medicare beneficiaries.
  
  
  METHODS
  Difference-in-difference analysis of drug adherence by AMI patients stratified by low-income subsidy (LIS) status and benefit phase.
  
  
  METHODS
  Subjects were identified with an AMI diagnosis in Medicare Part A files between April 2006 and December 2007 and followed until December 2008 or death (N = 8,900). Adherence was measured as percent of days covered (PDC) per month with four drug classes used in AMI treatment: angiotensin-converting enzyme (ACE) inhibitors/angiotensin II receptor blockers (ARBs), beta-blockers, statins, and clopidogrel. Monthly exposure to Part D benefit phases was calculated from flags on each Part D claim.
  
  
  RESULTS
  For non-LIS enrollees, transitioning from the initial coverage phase into the Part D coverage gap was associated with statistically significant reductions in mean PDC for all four drug classes: statins (-7.8 percent), clopidogrel (-7.0 percent), beta-blockers (-5.9 percent), and ACE inhibitor/ARBs (-5.1 percent). There were no significant changes in adherence associated with transitioning from the gap to the catastrophic coverage phase.
  
  
  CONCLUSIONS
  As the Part D doughnut hole is gradually filled in by 2020, Medicare Part D enrollees with critical diseases such as AMI who rely heavily on brand name drugs are likely to exhibit modest increases in adherence. Those reliant on generic drugs are less likely to be affected.
authors.affiliation: Department of Pharmaceutical Health Services Research, Peter Lamy Center on Drug Therapy and Aging, University of Maryland Baltimore, Baltimore, MD.
authors.forename: Bruce
authors.initials: B
authors.lastname: Stuart
authors.forename: Amy
authors.initials: A
authors.lastname: Davidoff
authors.forename: Mujde
authors.initials: M
authors.lastname: Erten
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Gottlieb
authors.forename: Mingliang
authors.initials: M
authors.lastname: Dai
authors.forename: Thomas
authors.initials: T
authors.lastname: Shaffer
authors.forename: Ilene H
authors.initials: IH
authors.lastname: Zuckerman
authors.forename: Linda
authors.initials: L
authors.lastname: Simoni-Wastila
authors.forename: Lynda
authors.initials: L
authors.lastname: Bryant-Comstock
authors.forename: Rahul
authors.initials: R
authors.lastname: Shenolikar
mesh_terms: D000208:Acute Disease; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002317:Cardiovascular Agents / Q000008:administration & dosage* / Q000191:economics* / Q000627:therapeutic use; D004363:Drug Utilization; D055317:Evidence-Based Practice; D005260:Female; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data; D008297:Male; D054524:Medicare Part D / Q000706:statistics & numerical data*; D009203:Myocardial Infarction / Q000188:drug therapy*; D012111:Residence Characteristics; D012737:Sex Factors; D012959:Socioeconomic Factors; D014481:United States; D016903:Drug Monitoring
chemical_list: D002317:Cardiovascular Agents
keywords: AMI; Medicare Part D; benefit design; evidence-based drugs