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Prevalence of Unplanned Hospitalizations Caused by Adverse Drug Reactions in Older Veterans

Authors

  • Zachary A. Marcum PharmD, MS,

    Corresponding author
    • Geriatrics
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  • Megan E. Amuan MPH,

    1. Bedford Veterans Affairs Medical Center, Bedford, Massachusetts;
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  • Joseph T. Hanlon PharmD, MS,

    1. Geriatrics
    2. Department of Pharmacy and Therapeutics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania;
    3. Geriatric Research, Education and Clinical Center
    4. Center for Health Equity Research and Promotion, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania;
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  • Sherrie L. Aspinall PharmD, MSc,

    1. Department of Pharmacy and Therapeutics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania;
    2. Center for Health Equity Research and Promotion, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania;
    3. Veterans Affairs Center for Medication Safety, Hines, Illinois;
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  • Steven M. Handler MD, PhD,

    1. Geriatrics
    2. Biomedical Informatics, School of Medicine
    3. Geriatric Research, Education and Clinical Center
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  • Christine M. Ruby PharmD,

    1. Geriatrics
    2. Department of Pharmacy and Therapeutics, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania;
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  • Mary Jo V. Pugh PhD

    1. Veterans Evidence-Based Research Dissemination and Implementation Center, South Texas Veterans Health Care System
    2. Department of Epidemiology and Biostatistics
    3. Division of Geriatrics and Gerontology, Department of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas
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Address correspondence to Zachary A. Marcum, Department of Medicine (Geriatrics), University of Pittsburgh, Kaufmann Medical Building, Suite 500, 3471 Fifth Avenue, Pittsburgh, PA 15213. E-mail: zam12@pitt.edu

Abstract

Objectives

To describe the prevalence of unplanned hospitalizations caused by adverse drug reactions (ADRs) in older veterans and to examine the association between this outcome and polypharmacy after controlling for comorbidities and other patient characteristics.

Design

Retrospective cohort.

Setting

Veterans Affairs Medical Centers.

Participants

Six hundred seventy-eight randomly selected unplanned hospitalizations of older (aged ≥ 65) veterans between October 1, 2003, and September 30, 2006.

Measurements

Naranjo ADR algorithm, ADR preventability, and polypharmacy (0–4, 5–8, and ≥9 scheduled medications).

Results

Seventy ADRs involving 113 drugs were found in 68 (10%) hospitalizations of older veterans, of which 25 (36.8%) were preventable. Extrapolating to the population of more than 2.4 million older veterans receiving care during the study period, 8,000 hospitalizations may have been unnecessary. The most common ADRs that occurred were bradycardia (n = 6; beta-blockers, digoxin), hypoglycemia (n = 6; sulfonylureas, insulin), falls (n = 6; antidepressants, angiotensin-converting enzyme inhibitors), and mental status changes (n = 6; anticonvulsants, benzodiazepines). Overall, 44.8% of veterans took nine or more outpatient medications and 35.4% took five to eight. Using multivariable logistic regression and controlling for demographic, health-status, and access-to-care variables, polypharmacy (≥9 and 5–8) was associated with greater risk of ADR-related hospitalization (adjusted odds ratio (AOR) = 3.90, 95% confidence interval (CI) = 1.43–10.61 and AOR = 2.85, 95% CI = 1.03–7.85, respectively).

Conclusion

ADRs, determined using a validated causality algorithm, are a common cause of unplanned hospitalization in older veterans, are frequently preventable, and are associated with polypharmacy.

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