Emory Report
April 4, 2005
Volume 58, Number 25


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April 4, 2005
'Safe' drugs can cause adverse effects, RSPH study finds


Of adverse drug events experienced by elderly Medicare patients, the vast majority are caused by commonly prescribed medications (not “high-risk” drugs), and the highest percentage of events was reported by patients using common cardiovascular, anti-inflammatory and cholesterol-lowering agents. The results are published in the March 2005 issue of The American Journal of Managed Care.

The study was conducted by Kimberly Rask, associate professor of health policy and management in the Rollins School of Public Health, along with colleagues from the Emory Center on Health Outcomes and Quality, the University of South Florida (Tampa), Covance Clinical Development Services, (Princeton, N.J.), and the Georgia Division of Public Health.

Using previous research that identified groups of potentially dangerous medications for the elderly, Rask and her team of researchers studied pharmacy claim data from managed-care companies to identify high-risk patients.

The researchers found that elderly patients prescribed the high-risk medications had similar rates of adverse drug events as those who were not taking them. The most reported events were attributed to cardiovascular agents (21.6 percent), anti-inflammatory agents (12.2 percent) and cholesterol-lowering agents (7.9 percent). Only two of the medications associated with self-reported adverse drug events were on the health plan’s list of potentially risky medications.

“Our hope was to identify the patients at risk so health plans could be better designed to potentially prevent the dangerous side effects,” Rask said. “However, these results mean that trying to eliminate dangerous side-effects in older patients is difficult; there isn’t a simple distinction between ‘bad’ medicines that cause side effects and ‘good’ medicines that improve health. Many important medicines that improve health can also have serious side effects.”

The study’s methodology involved telephone surveys of random samples of 211 individuals over age 65 who were taking a potentially contraindicated (harmful) medication, and of another random sample of 195 people not taking the “risky” medications. Study participants were continuously enrolled in Medicare managed care from July 1999 through June 2000, and all participants were identified through pharmacy claim data.

Participants were asked a series of questions related to their general health status, prescription drug use, adherence to medical regimen and recent adverse drug events. At the time of the interviews, a total of 134 adverse drug events during the previous six months were reported by 24.4 percent of all respondents; only 1.5 percent of the self-reported events were attributed to a potentially contraindicated medication.

While 31.9 percent of enrollees taking a potentially contraindicated medication reported an adverse drug event, 22.8 percent of enrollees not taking one of the potentially contraindicated medications reported an adverse drug event. Although not statistically significant, the higher rate of adverse drug events among those in the high-risk cohort may have been due to the concurrent use of multiple medications, rather than the specific use of the contraindicated medications, the study concluded.

Rask noted that patients should understand why they are taking each medicine, know what side effects might occur and what they should do if they experience a side effect. It is the patients’ responsibility, she said, to make sure their doctors are aware of all medications they are taking, including over-the-counter drugs.

“Patients, doctors and pharmacists have to work together to prevent serious side effects,” Rask said. “Pharmacists are a great resource for both patients and doctors—they can help identify medications that have the desired health benefit but decrease the likelihood of side effects.”