Adverse drug events among older persons in the outpatient setting are both common and preventable

Study in JAMA suggests range of causes and strategies for prevention

March 4, 2003

WORCESTER, Mass.—Medication-related injuries among older persons seen in clinics and physician offices are both quite common and often preventable, according to a study published in the current issue of the Journal of the American Medical Association (JAMA: 2003;289:1107-1116).  The results have broad implications for the elderly population in the United States, which as a group use more medications than younger patients. More than 90 percent of older Americans take at least one medication a week and 40 percent of them use five or more different drugs a week.

According to Jerry H. Gurwitz, MD, executive director of the Meyers Primary Care Institute (MPCI), a joint endeavor of the Fallon Foundation and the University of Massachusetts Medical School; the Dr. John Meyers Professor of Primary Care Medicine at UMMS; and corresponding author for the study,  “Among elderly persons cared for in the outpatient setting, medication-related injuries are very common – about fifty adverse drug events for every thousand persons followed for a year.  And about one-quarter of the adverse drug events described in this study were felt to be potentially preventable.” 

Co-authors of the study were UMMS faculty Terry S. Field. DSc; Leslie R. Harrold, MD, MPH; Kristin Debellis, PharmD; Andrew C. Seger, RPh; Cynthia Cadoret; Leslie S. Fish, PharmD; Lawrence Garber, MD; and Michael Kelleher, MD; plus Jeffrey Rothschild, MD, MPH and David W. Bates, MD, MSc, both of Brigham and Women’s and Partners HealthCare System.

Interestingly, more severe adverse drug events were twice as likely to be considered preventable than less serious ones.  “Clearly this offers an incredible opportunity to impact meaningfully on the health of the growing population of elderly in our country,” said Gurwitz.  “If we generalize the findings of this study to the population of the approximately 38 million Medicare enrollees, it would suggest that more than 1.9 million adverse drug events occur in this population each year—including 180,000 life-threatening or fatal events.  The results of this suggest that many of these events are potentially preventable.”

Another important finding was that many preventable adverse drug events were due to prescribing errors or errors in drug monitoring, but a significant number of adverse drug events described in this study were related to nonadherence on the part of the patient.  “This is one of the first studies to actually show that patient noncompliance with prescribing and dispensing information causes a substantial number of adverse drug events,” says Gurwitz, “and suggests that health care providers must do a much better job of educating older patients about the safe use of medications. Patients must become ‘partners’ in their own health care; in the case of prescription drug use, this is emphatically the case. “

Additional findings of the study:

  • Drugs commonly involved in preventable adverse drug events were cardiac medications, diuretics, pain medications, drugs for diabetes, and blood thinners. Common events included kidney problems, bleeding, and hypoglycemic reactions.
  • Prescribing problems included the use of medication that interacted with another drug the patient was already taking, or prescribing too high a dose of medication.  Monitoring problems are common among patients using blood thinners.
  • Examples of patient nonadherence include:  taking the wrong dose; continuing to take medication despite instructions by the health care provider to discontinue drug therapy; refusal to take a needed medication; continuing to take a medication despite recognized side effects or drug interactions known to the patient; and taking another person’s medication.

It appears that if effective systems are in place for prescribing and monitoring drugs, such as a computerized prescribing systems (also known as computerized physician order entry), the number of preventable drug injuries could be reduced substantially.    Physician order entry programs can alert prescribers of medications to potential problems such as excessive doses based on a patient’s poor kidney function, allergies, or a dangerous interaction with a drug the patient is already receiving.  These programs can also cue health care providers to monitor certain patients more closely for early signs of adverse drug events.

“We’re interested in educating and warning health care providers about potential problems at the time when a drug is prescribed,” Gurwitz said.  “If it can be demonstrated conclusively that computerized physician order entry works in the outpatient setting, it might lead to health care policy changes to encourage widespread use of this technology.”  Such technologies have already been shown to prevent serious medication errors in the hospital setting.

Gurwitz observes that “studies that analyze how things like adverse drug events occur are a very important step in the movement to make health care environments safer and reduce preventable medical errors.  Such analysis helps identify better systems to prevent problems.  A key component of this study, and what distinguishes it from other studies, is the analysis of how such adverse events might be prevented – a focus on making systems of care safer for both physicians and patients.”

The study, funded by a grant from the National Institute on Aging (one of the National Institutes of Health), in conjunction with the Agency for Healthcare Research and Quality is part of an ongoing series of studies being performed by the investigators. 

“Our study findings reinforce the importance of patient safety research.  It remains challenging for health care organizations to participate in studies such as this, and few are currently allowing this to happen, says Gurwitz. “Our research strongly suggests that every health care organization in this country should have  programs in place for identifying medication errors that lead to adverse drug events, in order to develop better strategies to prevent them.”

The Meyers Primary Care Institute is a joint endeavor of the Fallon Foundation and the University of Massachusetts Medical School, with a mission to promote primary care research and education.

The Fallon Foundation is a non-profit, charitable organization dedicated to serving its communities through health promotion, public education in health maintenance and disease prevention, and provision of health-care services. Since its establishment in 1998, the Fallon Foundation has given more than $2 million in donations, sponsorships, scholarships and support to communities throughout eastern and central Massachusetts.

The University of Massachusetts Medical School is one of the fastest growing medical schools in the country, attracting more than $143 million in research funding annually.  A perennial top ten finisher in the annual US News & World Report ranking of primary care medical schools, UMMS comprises a medical school, graduate school of nursing, graduate school of biomedical sciences and an active research enterprise, and is a leader in health sciences education, research, and public service. UMMS is the academic partner of UMass Memorial Health Care, and a proud partner of the Fallon Foundation in the Meyers Primary Care Institute.  Visit UMMS online at and the MPCI at .


Contact: Mark L. Shelton, 508-856-2000