Adverse Drug Events


Four commonly prescribed drugs are responsible for most emergency room visits.

Each year in the United States, adverse drug events, such as allergic reactions and accidental overdoses, cause about 100,000 hospitalizations, and 48% of people hospitalized were aged 80 or older. Researchers at the Centers for Disease Control and Prevention used adverse-event data from the National Electronic Injury Surveillance System—Cooperative Adverse Drug Event Surveillance project from 2007 through 2009 to estimate the frequency and rates of hospitalization after emergency department visits for adverse drug events. Of the 5,077 cases identified, there were 99,628 emergency hospitalizations for adverse drug events in adults 65 years of age.. Two thirds (65.7%) of hospitalizations were due to unintentional overdoses. Interestingly, only 4 medications or medication classes were implicated alone or in combination in 67% f the hospitalizations: warfarin (33%), insulins (14%), oral antiplatelet agents (13%), and oral hypoglycemic agents (11%). High-risk medications were implicated in only 1.2% of hospitalizations.

The researchers concluded that most emergency hospitalizations for adverse drug events in older adults resulted from 4 commonly used medications, and relatively few resulted from medications typically designated as high-risk or inappropriate. In particular, improved management of oral antithrombotic and hypoglycemic drugs has the potential to reduce hospitalizations for adverse drug events.


Budnitz DS, Lovegrove MC, Shehab N, Richards CL. Emergency hospitalizations for adverse drug events in older Americans. N Engl J Med 2011;365:2002-2012.

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