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Logo of bmjThis ArticleThe BMJ
BMJ. 2007 September 22; 335(7620): 585.
PMCID: PMC1989009

Number of serious adverse events doubles in seven years in US

The number of reported serious adverse events from drug treatment more than doubled in the United States from 1998 to 2005, rising from 34 966 to 89 842, says a new study.

Over the same period the number of deaths relating to drugs nearly tripled, from 5519 to 15 107, show data from the US Food and Drug Administration's adverse event reporting system, which collects all reports of adverse events submitted voluntarily to the agency either directly or through drug manufacturers (Archives of Internal Medicine 2007;167:1752-9).

Using extracts from the system that were published for use by researchers, the study's authors—Thomas Moore and Michael Cohen, of the Institute for Safe Medication Practices at Wake Forest University, Winston-Salem, North Carolina, and Curt Furberg, of the university's public health sciences division—analysed all adverse drug events and treatment errors reported to the agency from 1998, when the FDA started operating the system, to 2005.

Over the period the number of reported serious events grew four times faster than the total number of prescriptions to outpatients, which increased from 2.7 billion to 3.8 billion. In the subset of drugs associated with 500 or more reports in any year, those drugs that were withdrawn for safety reasons accounted for 26% of the reported events in 1999, this percentage falling to less than 1% in 2005. For 13 new biotechnology products, the number of reported serious events grew by nearly 16-fold, from 580 reported events in 1998 to 9181 in 2005.

A relatively small number of drugs were responsible for the overall increase in the number of adverse events reported: 298 of the 1489 drugs identified (20%) from the data accounted for 407 394 of the 467 809 events (87%).

Better systems for managing the risks from prescription drugs are needed, the authors say. But they also say that the increase may be partly due to a population increase as well as to greater reliance on intensive drug treatment. Drugs to relieve pain and those that alter the immune system were the drugs that were likeliest to result in death.

In Canada in 2006 the federal health department received reports of 10 518 cases of suspected adverse reactions to drug treatments, up by 108 from the figure for 2005. However, the country's adverse drug reactions database has been criticised for being plagued by under-reporting and for not being used optimally (, 22 May 2004, doi: 10.1136/bmj.328.7450.1222-f).

Meanwhile, a new Canadian study has said that mixing herbal medicines with prescription drugs could pose undiscovered health risks because many negative reactions are not being reported or tracked (

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