Adverse drug events put patients’ lives at risk.

ADEs, the harmful and unintended consequences of medication use, are a leading cause of unplanned hospital admissions, and rank between the 4th and 6th cause of death in North America.1234

In Canada, ADEs cause or contribute to almost 2 million emergency department visits annually. That means ADEs are involved about 1 in 9 adult visits to the emergency department. And, in British Columbia, ADEs account for 240,000 ED visits and 480,000 hospital days every year.

While some ADEs are related to unknown or unexpected reactions associated with a medication, many, if not most, ADEs are preventable and are related to human error and the complexities of care, prescribing, dispensing, and medication use. 56

Most importantly, from the existing research and our own prospective studies, we conservatively estimate that fully 30% of preventable ADEs requiring hospital admission may be repeat events that could be prevented with more effective ways of communicating relevant ADE information.78


ADE Case: ADE from a pharmacist's perspective

Clinical pharmacist, Vancouver General Hospital, 2012:

“I saw a diabetic patient today who was discharged from [another local hospital] on Friday, where he was admitted for hypoglycemia due to glyburide [a medication]. The physician there asked him to stop the glyburide, and gave him a prescription for gliclazide, which has a lower risk of hypoglycemia.”

“The patient presented here today with a critically low blood sugar of two, was treated, and then became hypoglycemic again. When I looked at the patient’s blister pack I was horrified to discover both glyburide and gliclazide. It turns out the patient had been given a discharge prescription for gliclazide, but there was no note on the discharge prescription to discontinue the glyburide, although I wouldn’t have thought that would be necessary. Neither the GP nor the community pharmacist were aware of what had happened."

Most ADEs go unreported

Another major obstacle in preventing adverse drug events is underreporting to oversight bodies. Studies show that fewer than 5% of ADEs are reported to oversight bodies, though there is evidence suggest that this number may actually be less than 1%. 91011 Both documenting ADEs in clinical practice (e.g. in medical charts) and reporting ADEs to Health Canada are important to reduce harm from ADEs.

ADE Case: A patient's perspective

I was feeling unwell and not like myself: I was confused, anxious, and I couldn’t find the right words. I was taken to the hospital, but I didn’t really understand what was going on.

During the hospital visit, I felt even more anxious because there were lots of people rushing around. They did a bunch of tests, and they mentioned something about high levels, but I didn’t understand what they were talking about. I have a history of high blood pressure, and I think it was related. The doctor said one of my medications was causing a problem and that I should stop taking it.  I didn’t have a pen and paper to write down what she said. I soon started to feel much better and went home.

A couple months later, I went to see my family doctor for a routine check-up. She wrote my usual prescriptions, and I picked them all up at the pharmacy on the way out. I take so many different medications these days so the pharmacy puts them in daily blister packs for me to keep track. But soon I started to feel unwell again. I went back to the hospital, and the doctor told me I had the same medication problem as last time.

Once I started to feel better, I wondered – the doctors and pharmacists are always typing into computers, don’t they know what medications I’m taking and what caused problems before? How can I stop this from happening again?

Adapted from an account in Van der Linden, et al 2010. 12

ADE information is not shared effectively

In clinical practice, ADEs are often not documented in medical records, and not communicated between care providers and across healthcare sectors electronically.13 Our health care system currently relies heavily on patients and families to communicate ADE information among their care providers. If ADE information is shared directly between health care providers, it is largely communicated using paper, fax or phone. As a result, information often calls through the cracks, and care providers may unintentionally re-expose patients to culprit medications; medications that previously caused clinically significant ADEs or were previously identified as contraindicated.14

ADE Case: ADE from a doctors’ perspective

Jacob* is a 75-year-old man who lives at a nursing home. Doctors describe him as a “very medically complex” patient – he has multiple cardiovascular and kidney issues, and takes at least eight different medications.

One day, Jacob begins to feel weak. He and his wife go the emergency room, and I find Jacob has a very slow heart rate of 36 beats per minute (60-100 beats per minute is considered normal). Jacob tells me he takes 5 mg of bisoprolol, a kind of beta blocker, every night before bed for his atrial fibrillation (abnormal heart rhythm).  Under certain circumstances, beta blockers can dangerously slow down heart rates.

Then, I realize – I am looking at a repeat ADE. It turns out that, just three months earlier, Jacob had gone to a different hospital, experiencing similar feelings of weakness. During that visit, another doctor also diagnosed bradycardia, and recommended that Jacob should stop taking a beta blocking medication, that time called metoprolol. A couple weeks after his first experience with bradycardia, Jacob had visited the hospital for acute on chronic kidney disease and healthcare associated pneumonia. He was treated, prescribed a beta blocker – bisoprolol – and sent home, with no one knowing the beta blocker would cause a repeat ADE.

*Not the patient’s real name