Ethnic Disparities in Adherence to Antihypertensive Medications of Medicare Part D Beneficiaries

Authors

  • Holly M. Holmes MD,

    Corresponding author
    • Department of General Internal Medicine, UT MD Anderson Cancer Center, Houston, Texas
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  • Ruili Luo PhD,

    1. Department of General Internal Medicine, UT MD Anderson Cancer Center, Houston, Texas
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  • Joseph T. Hanlon PharmD, MS,

    1. Division of Geriatric Medicine, Departments of Pharmacy and Therapeutics and Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania
    2. Geriatric Research, Education, and Clinical Center, Pittsburgh, Pennsylvania
    3. Center for Health Equity Research and Promotion, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania
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  • Linda S. Elting DrPH,

    1. Department of Biostatistics, UT MD Anderson Cancer Center, Houston, Texas
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  • Maria Suarez-Almazor MD, PhD,

    1. Department of General Internal Medicine, UT MD Anderson Cancer Center, Houston, Texas
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  • James S. Goodwin MD

    1. Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
    2. Sealy Center on Aging, University of Texas Medical Branch, Galveston, Texas
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Address correspondence to Holly M. Holmes, Department of General Internal Medicine, UT MD Anderson Cancer Center, 1515 Holcombe Blvd Unit 1465, Houston, TX 77030. E-mail: hholmes@mdanderson.org

Abstract

Objectives

To determine the level of adherence to medications and characteristics of Part D beneficiaries associated with higher levels of antihypertensive medication adherence.

Design

Retrospective cohort study.

Setting

Medicare claims and Part D event files.

Participants

Medicare Part D enrollees with prevalent uncomplicated hypertension who filled at least one antihypertensive prescription in 2006 and two prescriptions in 2007.

Measurements

Medication adherence was defined as an average medication possession ratio of 80% or greater. Potential factors associated with adherence evaluated were age, sex, race or ethnicity, socioeconomic factors, comorbidity, medication use, copayments, being in the coverage gap, and number of unique prescribers.

Results

Overall adherence was 79.5% of 168,522 Medicare Part D enrollees with prevalent uncomplicated hypertension receiving antihypertensive medicines in 2007. In univariate analysis, adherence varied significantly according to most patient factors. In multivariable analysis, lower odds of adherence persisted for blacks (odds ratio (OR) = 0.53, 95% confidence interval (CI) = 0.51–0.55), Hispanics (OR = 0.58, 95% CI = 0.55–0.61), and other non-white races (OR = 0.80 95% CI = 0.75–0.85) than for whites. Greater comorbidity and concurrent medication use were also associated with poorer adherence. Adherence was significantly different across several geographic regions.

Conclusion

A number of associations were identified between patient factors and adherence to antihypertensive drugs, with significant differences in adherence according to ethnicity. Improving adherence could have significant public health implications and could improve outcomes specific to hypertension, as well as improving cost and healthcare utilization.

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