Suboptimal Prescribing in Elderly Outpatients: Potentially Harmful Drug-Drug and Drug-Disease Combinations

Authors

  • Chunliu Zhan MD, PhD,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Rosaly Correa-de-Araujo MD, MSc, PhD,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Arlene S. Bierman MD, MS,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Judy Sangl PhD,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Marlene R. Miller MD,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Stephen W. Wickizer PharmD,

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author
  • Daniel Stryer MD

    1. From the *Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MarylandDepartment of Pediatrics, Johns Hopkins University, Baltimore, MarylandSt. Michael's Hospital, Toronto, Canada§National Cancer Institute, National Institutes of Health, Frederick, Maryland
    Search for more papers by this author

  • This paper was a result of an intramural research project conducted at the Agency for Healthcare Research and Quality (AHRQ). No external funding was used. The authors of this article are responsible for its content. No statement in this article should be construed as an official position of the AHRQ or the U.S. Department of Health and Human Services.

Chunliu Zhan, MD, PhD, Center for Quality Improvement and Patient Safety, Agency for Healthcare Research and Quality, 540 Gaither Road, Rockville, MD 20850. E-mail: czhan@ahrq.gov

Abstract

Objectives: To assess the prevalence and correlates of potentially harmful drug-drug combinations and drug-disease combinations prescribed for elderly patients at outpatient settings.

Design: Retrospective analysis of the 1995–2000 National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS).

Setting: Physician offices and hospital outpatient departments.

Participants: Outpatient visits by patients aged 65 and older in the NAMCS and NHAMCS (n=70,203).

Measurements: Incidences of six drug-drug combinations and 50 drug-disease combinations that can place elderly patients at risk for adverse events according to expert consensus panels.

Results: Overall, 0.74% (95% confidence interval (CI)=0.65–0.83) of visits with two or more prescriptions had at least one inappropriate drug-drug combination, and 2.58% (95% CI=2.44–2.72) of visits with at least one prescription had one or more inappropriate drug-disease combinations. Of visits with a prescription of warfarin, 6.60% (95% CI=5.46–7.74) were prescribed a drug with potentially harmful interaction. Of patients with benign prostatic hypertrophy, 4.06% (95% CI=3.06–5.06) had at least one of six drugs that should be avoided. The number of drugs prescribed is most predictive of inappropriate drug-drug and drug-disease combinations.

Conclusion: Potentially harmful drug-drug and drug-disease combinations occur in various degrees in outpatient care in the elderly population. Targeting combinations such as those involving warfarin that are high in prevalence and potential harm offers a practical approach to improving prescribing and patient safety.

Ancillary