Patient safety

Study finds 50% medication error rate for some patients

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 unplanned.

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.