Study: Drug reactions kill an estimated 100,000 a year

April 14, 1998
Web posted at: 10:35 p.m. EDT (0235 GMT)

CHICAGO (CNN) -- Adverse reactions to prescription and over-the-counter medicines kill more than 100,000 Americans and seriously injure an additional 2.1 million each year, researchers say.

Such reactions -- which do not include prescribing errors or drug abuse -- rank at least sixth among causes of death in the United States, behind heart disease, cancer, lung disease, strokes and accidents, according to a report published in this week's Journal of the American Medical Association. The report was based on an analysis of existing studies.

"Serious adverse drug reactions are frequent ... more so than generally recognized," the researchers said.

Researchers at the University of Toronto examined 39 studies and estimated that an average of 106,000 deaths at U.S. hospitals in 1994 were due to bad reactions to drugs.

"We're not saying, 'Don't take drugs.' They have wonderful benefits. But what we're arguing is that there should be increased awareness also of side effects, which until now have not been too well understood," said Dr. Bruce H. Pomeranz, principal investigator and a neuroscience professor at the University of Toronto.

The harm from adverse drug reactions includes allergic reactions to antibiotics and stomach bleeding from frequent doses of aspirin, Pomeranz said.

The study by Pomeranz and two colleagues, Jason Lazarou and Paul N. Corey, did not explore which medications or illnesses were involved.

Large number of deaths surprised researchers

The researchers analyzed studies of hospital patients conducted during a 30-year period, from 1966 to 1996. They found serious drug reactions affected 6.7 percent of patients overall and fatal drug reactions 0.32 percent.

In the study, serious injury was defined as being hospitalized, having to extend a hospital stay or suffering permanent disability.

The authors said the most surprising result was the large number of deaths. They found adverse drug reactions ranked between fourth and sixth among leading causes of death -- depending on whether they used their most conservative or most liberal estimates.

Between 76,000 and 137,000 U.S. hospital patients died from adverse reactions in 1994, and the "ballpark estimate" is 106,000, Pomeranz said. The low estimate, 76,000 deaths, would put drug reactions sixth. The ballpark estimate would put them fourth, he said.

The study found an additional 1.6 million to 2.6 million people were seriously injured. The ballpark estimate was 2.1 million.

More than two-thirds of the cases involved reactions outside hospitals rather than in hospitals, the authors reported.

The researchers said their results suggest an "important clinical issue." But they recommend cautious interpretation.

Experts differ over accuracy of results

Experts commended the study but disagreed about whether the results are on target.

An accompanying editorial by David Bates of Boston's Brigham and Women's Hospital urged careful analysis. Bates said "combining the results of small, heterogeneous studies does not necessarily bring one closer to the truth."

Bates said estimates may be high because the research may overrepresent large medical centers, which treat sicker than average patients who are prone to reactions.

Nevertheless, he added, "these data are important, and even if the true incidence of adverse drug reactions is somewhat lower than that reported ... it is still high, and much higher than generally recognized."

Dr. Sidney M. Wolfe, director of the consumer advocacy Public Citizen Health Research Group, said he believes the numbers are on target.

"I've read most of these studies, and they represent large hospitals, small hospitals ... a heterogeneous sample of the kinds of hospitals in this country, and include a whole range," Wolfe said.

He added that many serious injuries and deaths from bad drug reactions are preventable. Many drugs have safer available alternatives, and harmful interactions between drugs -- such as those prescribed by different doctors -- can be more carefully avoided, Wolfe said.

Doctors need to increase drug dosages slowly for many older patients who lack the drug tolerance of younger adults because their kidneys and livers have declined, Wolfe said.

Utah hospital offered as model

In addition, hospitals should find better ways to track and head off problems, the way a model computerized system does at LDS Hospital in Salt Lake City.

That hospital reported last year it discovered that 50 percent of its adverse reactions were potentially preventable -- including 42 percent that occurred because patients were given too much medicine for their weight and kidney function.

The hospital now automatically calculates patients' kidney function daily. It has reduced adverse reactions 75 percent and suggested that other facilities could easily do the same.

Wolfe said it is "inexcusable, given how inexpensive computers are," that other hospitals have not copied the system.

But the researchers say the best way to be protected is to be a well-educated patient and be your own advocate by asking questions and reading the information provided with prescriptions.

Medical Correspondent Dr. Steve Salvatore, The Associated Press and Reuters contributed to this report.

Related site:

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• JAMA - The Journal of the American Medical Association
  • Adverse Drug Reactions May Cause Over 100,000 Deaths Among Hospitalized Patients Each Year

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