Risk factors for adverse drug events among older adults in the ambulatory setting.

Terry S. Field, University of Massachusetts Medical School
Jerry H. Gurwitz, University of Massachusetts Medical School
Leslie R. Harrold, University of Massachusetts Medical School
Jeffrey Rothschild, Fallon Foundation
Kristin R. DeBellis, Fallon Foundation
Andrew C. Seger, Fallon Foundation
Jill C. Auger, Fallon Foundation
Leslie A. Garber, Fallon Foundation
Cynthia A. Cadoret, University of Massachusetts Medical School
Leslie S. Fish, Fallon Foundation
Lawrence D. Garber, Fallon Foundation
Michael Kelleher, Fallon Foundation
David W. Bates, Brigham and Women's Hospital

Abstract

OBJECTIVES: To gather information on patient-level factors associated with risk of adverse drug events (ADEs) that may allow focus of prevention efforts on patients at high risk.

DESIGN: Nested case-control study.

SETTING: Large multispecialty group practice in New England.

PARTICIPANTS: All Medicare enrollees cared for by a multispecialty group practice during 1 year (N=30,397 person-years from July 1, 1999, through June 30, 2000). For each patient with an ADE, a control was randomly selected.

MEASUREMENTS: Data were abstracted from medical records on age, sex, comorbidities, and medication use at the time of the event.

RESULTS: ADEs were identified in 1,299 older adults. Independent risk factors included being female and aged 80 and older. There were dose-response associations with the Charlson Comorbidity Index and number of scheduled medications. Patients taking anticoagulants, antidepressants, antibiotics, cardiovascular drugs, diuretics, hormones, and corticosteroids were at increased risk. In the analysis of preventable ADEs, the dose-response relationship with comorbidity and number of medications remained. Patients taking nonopioid analgesics (predominantly nonsteroidal antiinflammatory drugs and acetaminophen), anticoagulants, diuretics, and anti-seizure medications were at increased risk.

CONCLUSION: Prevention efforts to reduce ADEs should be targeted toward older adults with multiple medical conditions or taking multiple medications, nonopioid analgesics, anticoagulants, diuretics, and antiseizure medications.