Minor Misdosage of ER Clot-Busting Drugs May be OK

Patient characteristics probably cause poor heart attack outcomes, study suggests

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TUESDAY, April 12, 2005 (HealthDay News) -- Death or serious complications in heart attack patients given powerful clot-busting drugs are more likely triggered by individual patient characteristics than drug-dosing errors, a new study finds.

The findings suggest busy ER doctors shouldn't be overly concerned about the possibility of minor dosing errors when using life-saving clot-busting drugs, the study authors said. Such concern could result in insufficient use of these drugs, known as fibrinolytic agents.

About one in three patients admitted to emergency departments with heart attack symptoms do not receive these drugs, noted researchers at Duke University Clinical Research Institute, in Durham, N.C. Doctors' concerns about potential problems due to incorrect dosing is one reason cited for this under-usage of clot-busting drugs, they said.

In the study, published in the April 13 issue of the Journal of the American Medical Association, the Duke team analyzed data from a study of almost 17,000 patients with heart attack symptoms given either on of these clot-busting drugs or a placebo.

About five percent of the patients received incorrect doses of these anticlotting drugs, the researchers reported. The 30-day death rate for patients who received an overdose was 9.8 percent, and 19.5 percent for those who received an underdose. Patients who received a correct dose had a death rate of 5.4 percent.

However, the same statistics held true for patients receiving an inactive placebo, too, the researchers noted.

There was a 10 percent death rate among patients who received an "overdose" of placebo, while those who received an placebo "underdose" had a death rate of 23.5 percent. Those who received a correct dose of placebo had a death rate of 5.4 percent.

Since roughly similar findings were found in both active drug and inactive placebo, this suggests there's something about individual patients that's driving the results, rather than either of these agents, the researchers said.

"These findings are counterintuitive, when given the wrong dose of placebo, there was [also a] much worse outcome," Dr. Christopher Granger, a Duke University Medical Center cardiologist, said in a prepared statement.

"This is clearly a remarkable finding, as well as a reason to pause -- whenever we see a relationship between a treatment and an outcome, we must be careful in ascribing cause and effect. Other factors may also be involved, and additional studies are need to better understand what these factors may be," Granger said.

"We have found that there does not appear to be a cause-and-effect relationship between small dosing errors and worse outcomes for patients. These findings should be somewhat reassuring to busy physicians in emergency rooms who can assume that as long as the drugs are given carefully to the right patients, small misdosings should not lead to bad outcomes," Granger said.

More information

The Cleveland Clinic Foundation has more about treating heart attack.

SOURCE: Duke University, news release, April 12, 2005

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