The study results, published in the Jan. 24 issue of the Archives of Internal Medicine, will help researchers develop strategies for decreasing the number of adverse drug events (ADEs) –– instances of injury arising from prescription medicines –– in patients across the country, the authors suggest.
"In an earlier study, we tracked ADEs in a group of patients being treated in primary-care practices. We expected that the same percentage of outpatients would have ADEs as had been found in studies of hospitalized patients –– about 7 percent," says the study's lead author, Saul N. Weingart, M.D., Ph.D., director of the Center for Patient Safety at Dana-Farber Cancer Institute. He conducted the research while on staff at Beth Israel Deaconess Medical Center. "We were astounded to find the actual rate was 25 percent, and that many of the ADEs were preventable. In the new study, we wanted to see the extent to which doctor/patient communication about patients' medication symptoms resulted in such incidents."
David W. Bates, MD, MSc, of Brigham and Women's Hospital, is the study's senior author. The investigators were based at Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, and the Harvard School of Public Health.
The study involved 661 patients at four adult primary-care practices in Boston. Researchers interviewed patients and reviewed their medical records to tally the number of ADEs reported over a three-month period. They also surveyed physicians whose patients experienced medication-related symptoms. A panel of physicians and pharmacists reviewed each reported symptom to determine whether it constituted a true adverse drug event.
The researchers found that while many patients experienced ADEs, they failed to report a surprising number of them –– 31 percent –– to their physicians. And while physicians often did change the therapies of patients who reported medication problems, they didn't order such changes 24 percent of the time.
"For every symptom that patients experienced but failed to report, one in five resulted in an adverse drug event that could have been prevented or been made less severe," Weingart says. "For every symptom that patients did report but doctors failed to act on, two-thirds resulted in an adverse drug event."
The investigators also found that patients who were taking several medications and had allergies to multiple medications were more likely to report symptoms to their doctors. Male physicians and physicians who worked at two practices were more likely than average to change therapies.
The investigators didn't inquire into patients' reasons for not reporting some of the adverse side effects they experienced. They speculate, however, that patients may have been reticent about discussing side effects that were either common or relatively mild, or that were embarrassing (such as diarrhea or sexual dysfunction). And although doctors were not asked why they didn't change medications in some cases, the researchers say doctors may have decided that side effects were tolerable after discussing them with patients.
"In cases where doctors did change a medication in response to a patient's symptoms, we found that the number of adverse drug events was very small," notes Weingart, who is an assistant professor of medicine at Harvard Medical School.
The vast majority of ADEs that occurred during the study were not dangerous, he continues, "but 12 percent of them were considered serious; that is, they could have caused significant problems such as organ damage or bleeding had they not been corrected."
The 'moral' of the study is that "patients have a lot to tell us about symptoms they experience due to their medications," Weingart observes. "And there is a great deal of opportunity for doctors to prevent harm by asking questions regularly about medications and medication-related problems, and by taking patients' comments seriously." Weingart and his colleagues are currently exploring whether technological tools, such as e-mail reminder messages, can encourage patients to report side effects to their physicians.
The study was funded with a grant from the Risk Management Foundation of the Harvard Medical Institutes. Weingart is supported by a Career Development Award from the U.S. Agency for Healthcare Research and Quality.
Dana-Farber Cancer Institute is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.
Journal
Archives of Internal Medicine