Study finds 50% medication error rate for some
Patients taking a high number of prescription medications who are then
unexpectedly admitted to hospital face a medication error rate of more
than 50 percent with their existing medications, one-third of which
could result in more serious complications, says a new study by
University of Toronto researchers.
Senior author Dr. Edward Etchells says he wasn’t surprised by the high
proportion of unintended medication errors. “In that kind of situation,
where a patient is taking quite a few medicines, is acutely ill and
possibly cognitively impaired, it’s very difficult to get an accurate
medication use history.
“The most common mistake is to be unaware that the patient is taking a
particular medicine, and there is no mechanism that would clue you into
a potential problem,” notes Etchells, a professor of medicine at U of T,
director of the Patient Safety Service at Sunnybrook and Women’s College
Health Sciences Centre and internal medicine physician at the hospital.
The study, published in the Feb. 28 issue of the Archives of Internal
Medicine, reports how researchers at U of T screened the medical charts
of 523 patients admitted to a U of T-affiliated teaching hospital over a
three-month period in 2003. Of that number, 151 patients were included
in their study: to be included patients had to be taking at least four
prescription medicines at home and their admission to hospital was
At the time of admission, the researchers reviewed these patients’
hospital charts to record medications prescribed by attending
physicians. A member of the research team then conducted an interview
with the patient or family and recorded a thorough medication history.
It was then determined whether there were any discrepancies between what
the patient reported during the interview and the medications that were
prescribed after admission.
All discrepancies were brought to the attention of the attending
physician team, and changes were made as necessary. Of the 151 patients,
the researchers found that 81 (53.6 percent) had at least one unintended
medication discrepancy. The most common error (46.4 percent) was the
omission of a regularly used medication.
While the majority of discrepancies were judged to have little or no
potential to cause harm, 38.6 percent of the discrepancies were
determined to have the potential to cause moderate to severe discomfort
or clinical deterioration.
“Until we have an automated system in place that tracks prescriptions
filled in Ontario, the best mechanism for finding it out is for the
patient or family member to say how they’re using the medications at
home,” says Etchells.
Dr. Etchells was an author on the landmark nation-wide study examining
adverse events in Canadian hospitals last May and is a leading Canadian
expert in patient safety issues.
Etchells advocates using a two-pronged approach to safeguarding against
medication error. First, he calls for the implementation of an automated
pharmacy database system – like the one in British Columbia – which
provides pharmacists and healthcare providers with a print out of drugs
prescribed to a patient.
Second, he suggests thorough interviews at the time of admission with
the patient or family member to determine how they’re taking the
medicines, as was done in this study. These thorough interviews took an
average of 24 minutes per patient to complete.
“This study doesn’t mean that people are doing things wrong or
neglecting their duties,” Etchells stresses. “This is a hard thing to
get correct, which is why I’m not surprised. This is exactly what you
expect to happen when you start to pay attention to medication safety.
You look for mistakes and you start to develop systems to deal with it.
So we’re proud of the results because we have also described a method
for addressing the problem, and we understand that staffing and time
will be required to deal with it.”
Study participants were generally older with a mean age of 77 years.
Patients were also admitted for a variety of medical conditions, from
gastrointestinal hemorrhage to heart failure or stroke. The researchers
also note that there seemed to be no significant associations between
these medication errors and other factors such as weekend or night time
admission or during high workload periods.
This study is the largest and most comprehensive of its kind in Canada,
states Etchells. He also emphasizes that the issues identified by this
study won’t necessarily apply to all areas of the hospital.
However, for those patients who take many drugs and are admitted to
hospital unexpectedly, he suggests that the patient or family members
bring with them the bottles of pills they are taking and a written list
that outlines exactly how the medicines are actually being used at home.
Other important safety lessons for patients from this study were never
to store medicines in other people’s medication bottles, and never use
your own supply of medicines while in the hospital without informing the
physician or nurse that you are doing so.