How Medicare Part D Benefit Phases Affect Adherence with Evidence-Based Medications Following Acute Myocardial Infarction.

Department of Pharmaceutical Health Services Research, Peter Lamy Center on Drug Therapy and Aging, University of Maryland Baltimore, Baltimore, MD.
Health Services Research (Impact Factor: 2.49). 06/2013; DOI: 10.1111/1475-6773.12073
Source: PubMed

ABSTRACT OBJECTIVE: Assess impact of Medicare Part D benefit phases on adherence with evidence-based medications after hospitalization for an acute myocardial infarction. DATA SOURCE: Random 5 percent sample of Medicare beneficiaries. STUDY DESIGN: Difference-in-difference analysis of drug adherence by AMI patients stratified by low-income subsidy (LIS) status and benefit phase. DATA COLLECTION/EXTRACTION 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. PRINCIPAL FINDINGS: 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.

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    ABSTRACT: Background Nonadherence to hormonal therapy is common and is associated with increased copayment amount. We investigated the change in adherence after the introduction of generic aromatase inhibitors (AIs) in 2010. Methods Using deidentified pharmacy and claims data from OptumInsight, we identified women older than 50 years on brand-name AIs (BAIs) and/or generic AIs (GAIs) for early breast cancer between January 1, 2007 and December 31, 2012. Clinical, demographic, and financial variables were evaluated. Adherence was defined as a medication possession ratio (MPR) 80% or greater. Results We identified 5511 women, 2815 (51.1%) on BAI, 1411 (25.6%) on GAI, and 1285 (23.3%) who switched from BAI to GAI. The median 30-day copayment was higher for BAI ($33.3) than for GAI ($9.04). In a multivariable Cox-proportional hazard analysis, women who took GAI were less likely to discontinue therapy (hazard ratio [HR] = 0.69, 95% confidence interval [CI] = 0.57 to 0.84) compared with BAI. Discontinuation was positively associated with a higher monthly copayment of $15 to $30 (HR = 1.21, 95% CI = 1.01 to 1.44) and more than $30 (HR = 1.49, 95% CI = 1.23 to 1.80) compared with less than $15. In a multivariable logistic regression analysis, adherence (medication possession ratio = 80%) was positively associated with GAI use (odds ratio = 1.53, 95% CI = 1.22 to 1.91) compared with BAI and inversely associated with increased monthly copayment. In addition, adherence was associated with a high annual income of more than $100k/year (odds ratio = 1.58, 95% CI = 1.17 to 2.11). Conclusions Higher prescription copayment amount was associated with nonadherence and discontinuation of AIs. After controlling for copayment, discontinuation was higher and adherence was lower with Brand AIs. Because nonadherence is associated with worse survival, efforts should be directed towards reducing out-of-pocket costs for these life-saving medications.
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