Preventable Medical Errors and Adverse Drug Events

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Every year, the cost of medical errors in the United States is $76 billion, which is about the same as the total medical cost of treatment and prevention of all cancers.

According to the Institute of Medicine (IOM), there are 50,000-100,000 deaths each in U.S. due to medical errors. Despite of advances in medical technology, mortality rate due to medical errors has increased over the past 30 years by almost 2-3 times, see Phillips et al (1998) . This is possibly due to the increase in outpatient visits in comparison to inpatient visits.

So what is an adverse drug event? An adverse drug event, also known as adverse drug reaction, is the undesired, negative consequences that come with the use of medications. This should be differentiated from side-effects, which could be associated with positive consequences in some cases.

Medical errors can lead to adverse drug events. This can occur during ordering of medication, transcription, distributing and administration. For instance, doctor’s handwritings are notoriously difficult to read, which cause pharmacist to misread the prescription. Another scenario is doctors may not know that a patient is allergic to certain drugs even the information maybe already stored somewhere.

It is estimated that adverse drug event occurs in about 7% of hospital admissions. 1% of adverse drug events are fatal and 42% are either life-threatening or serious. Deaths due to adverse drug events are more than deaths due to suicide, homicide, AIDS, or car accidents.

Adverse drug events also increase health care cost. On average, patients stay 2-3 days longer in hospital, with an increase in cost of $2500-$4000.

We probably still underestimate the health and cost impacts of adverse drug events since most adverse drug events are based on voluntary reporting.

Clearly, reducing the number of medical errors will not only save lives and improve patient care but also help to control the rising cost of health care in U.S. The application of information technology may bring down the number of medical errors and the associated adverse drug events. We will discuss the potential of information technology in the next article of the series.


D.P. Phillips,N. Christenfeld, and L.M. Glynn, Increase in U.S. medication-errordeaths between 1983 and 1993, Lancet 351 (1998) 643–644.

T.A. Brennan, L.L. Leape, N.M. Laird et al., Incidence of adverse events andnegligence in hospitalized patients, New England Journal of Medicine 324 (1991) 370–376.

L.L. Leape, T.A. Brennan, N. Laird et al., The nature of adverse events in hospitalized patients: results of the Harvard medical practice study II, NewEngland Journal of Medicine 324 (1991) 377–384.

E.J. Thomas, D.M. Sudderth, H.R. Burstein et al., Incidence and types ofadverse events and negligent care in Utah and Colorado, Medical Care 28(2000) 261–271.

L.T.Kohn, J.M. Corrigan, and M.S. Donaldson, editors,To Err is Human: Building a Safer Health System (National Academy Press,Washington, DC, 1999).

C.J. McDonald, M. Weiner, and S.L. Hui, Deaths due to medical errors are exaggerated in Institute of Medicine report, JAMA 284 (2000) 93–95.

This post is part of the series: Medical errors and adverse drug events

In this series of articles we review the impact of medical errors and adverse drug events, and discuss the possible solutions to this expanding problem in health care.

  1. Overview of Medical Errors and Adverse Drug Events
  2. Preventing Medical Errors: Use of Information Technology To Reduce Adverse Drug Events