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Comparative Study
. 2013 Jun 1;19(6):e214-24.

Effects of Medicare Part D coverage gap on medication adherence

Yuting Zhang  1 , Seo Hyon Baik, Judith R Lave
Affiliations
Comparative Study

Effects of Medicare Part D coverage gap on medication adherence

Yuting Zhang et al. Am J Manag Care. .

Abstract

Objectives: To evaluate the effects of the Medicare Part D coverage gap on pharmacy use among a national sample of Medicare beneficiaries and on medication adherence among 2 subsamples with heart failure and/or diabetes.

Study design: Pre-post design, with comparison group and propensity score weighting.

Methods: We used a 5% random sample of elderly Medicare beneficiaries enrolled in stand-alone Part D plans in 2007. The comparison group had full coverage in the gap, whereas the 2 study groups had either no coverage or generic-only coverage in the gap. Main outcomes included probability of filling a prescription, monthly pharmacy spending and number of prescriptions filled, and adherence measured by medication possession ratios.

Results: Relative to the comparison group, beneficiaries without drug coverage in the gap reduced the number of prescriptions filled per month by 16.0% (95% confidence interval [CI], 15.5%-16.5%); those with generic drug coverage in the gap reduced it by 10.8% (95% CI, 10.3%-11.4%). Most of the reduction was attributable to reduced use of brand-name drugs. Beneficiaries with heart failure reduced adherence to heart failure drugs by 3.6% (95% CI, 2.9%-4.2%) and beneficiaries with diabetes reduced antidiabetic medication adherence by 10.3% (95% CI, 9.4%-11.3%).

Conclusions: Medicare beneficiaries reduced medication use (mainly brand-name drugs) after entering the coverage gap. This result suggests that while beneficiaries' financial burden would continue because of the coverage gap, the gap would not result in a large reduction in medication adherence for essential drugs for diabetes and heart failure.

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Figures

Figure 1
Figure 1
Histograms of the Time Spent in the Gap by Group Abbreviation: LIS = low-income subsidy group.
See this image and copyright information in PMC

References

    1. Zhang Y, Donohue JM, Lave JR, O’Donnell G, Newhouse JP. The impact of the Medicare Part D drug benefits on pharmacy and medical care spending. N Engl J Med. 2009;361(1):52–61. - PMC - PubMed
    1. Zhang Y, Lave JR, Donohue JM, Fischer MA, Chernew ME, Newhouse JP. The impact of Medicare Part D on medication adherence among older adults enrolled in Medicare-Advantage products. Med Care. 2010;48(5):409–417. - PubMed
    1. Ketcham JD, Simon KI. Medicare Part D's effects on elderly patients' drug costs and utilization. Am J Manag Care. 2008;14(11 Suppl):SP14–SP22. - PubMed
    1. Kaiser Family Foundation. [Accessed July 10, 2011];The Medicare Prescription Drug Benefit. 2007 http://kff.org/medicare/upload/7044-06.pdf.
    1. Centers for Medicare & Medicaid Services. [Accessed February 3, 2011];Medicare Part D data symposium presentations. 2010 http://www.cms.gov/PrescriptionDrugCovGenIn/09_ProgramReports.asp.

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