Volume 48 | Number 6pt1 | December 2013

Abstract List

Bruce Stuart Ph.D., Amy Davidoff, Mujde Erten, Stephen S. Gottlieb, Mingliang Dai, Thomas Shaffer, Ilene H. Zuckerman, Linda Simoni‐Wastila, Lynda Bryant‐Comstock, Rahul Shenolikar


Assess impact of edicare Part D benefit phases on adherence with evidence‐based medications after hospitalization for an acute myocardial infarction.

Data Source

Random 5 percent sample of edicare beneficiaries.

Study Design

Difference‐in‐difference analysis of drug adherence by patients stratified by low‐income subsidy () status and benefit phase.

Data Collection/Extraction Methods

Subjects were identified with an diagnosis in edicare Part A files between pril 2006 and ecember 2007 and followed until ecember 2008 or death ( = 8,900). Adherence was measured as percent of days covered () per month with four drug classes used in treatment: angiotensin‐converting enzyme () inhibitors/angiotensin receptor blockers (s), beta‐blockers, statins, and clopidogrel. Monthly exposure to Part D benefit phases was calculated from flags on each Part D claim.

Principal Findings

For non‐ enrollees, transitioning from the initial coverage phase into the Part D coverage gap was associated with statistically significant reductions in mean for all four drug classes: statins (−7.8 percent), clopidogrel (−7.0 percent), beta‐blockers (−5.9 percent), and inhibitor/s (−5.1 percent). There were no significant changes in adherence associated with transitioning from the gap to the catastrophic coverage phase.


As the Part D doughnut hole is gradually filled in by 2020, edicare Part D enrollees with critical diseases such as 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.