The cost of adverse drug events

If you ever doubted that adverse events involving prescription drugs are costly, consider a new study that looks at what happens when these patients end up in the emergency room.

The study, which was published this week in the Annals of Emergency Medicine, tracked 1,000 patients who came to the emergency room at Vancouver General Hospital in Vancouver, B.C., Canada, for six months in 2006.

What the researchers found: 12 percent of these patients sought emergency care because of an adverse drug event, defined as “an unwanted and unintended medical event related to the use of medications.” Although this may not sound like a large number, the impact in terms of cost and utilization was substantial. Patients who came to the ER with prescription drug-related problems weren’t necessarily at greater risk of dying than other ER patients – but they were more likely to spend additional days in the hospital and more likely to have additional outpatient doctor visits. When they were tracked across six months of followup, their median monthly cost of care also was almost twice as high as that of other emergency patients – $325 (in Canadian dollars) vs. $96.

It’s not clear if the results would be similar among ER patients in the United States, although I suspect they are. The researchers controlled for age but there may have been other factors - overall health, for instance, or level of health literacy or overall number of prescription drugs being taken - that increased the likelihood these patients would experience an adverse drug event in the first place. Some of these additional factors also might have made it more likely the patient would be hospitalized or need additional followup care.

All in all, this study comes with a couple of important messages. First, adverse drug events often aren’t glaringly obvious, high-cost incidents, a fact that sometimes makes them less noticeable to the public. The researchers calculated the additional median cost in the hundreds, rather than thousands, of dollars.

Secondly, these incidents often fly below the radar screen in many ERs. If anything, they tend to be under-recognized. In an accompanying news release, the study’s lead author, Dr. Corinne Hohl, said, “Medication-related problems are not necessarily the first thing we look for in an emergency patient when we are trying to diagnose what is wrong.”

The real issue, the authors point out, is that the vast majority of adverse drug events are preventable.

Lowering the incidence of misadventures with prescription drugs won’t be easy, though. It’s a multi-level problem with no single solution.

Are patients these days simply being prescribed too many medications? Undoubtedly they are.

Polypharmacy, or the use of multiple prescription drugs, is becoming much more common, making it more challenging for people to take each drug correctly as prescribed and increasing the risk of unwanted drug interactions. Over-the-counter supplements have added yet another wrinkle, not only in their potential for outright misuse but for the risk of bad interactions with prescription drugs as well.

Do patients fully understand how to correctly take a prescription medication? Details matter; often you have to read the fine print. The label on my thyroid medication says I should take it on an empty stomach before breakfast. But the two-page handout I get from the pharmacy each year is much more specific: Take it at least one hour before breakfast, otherwise it won’t be absorbed as effectively.

Although price-shopping saves money, consumers should be aware of the down side. When they use two or more pharmacies so they can get a deal on a particular prescription drug, potentially bad interactions can be missed because the pharmacist doesn’t have their complete medication history.

The Vancouver hospital where this study took place is trying to make some changes. For starters, data from the study are being used to develop a screening tool to help ER doctors identify which patients are most at risk of an adverse drug event. Hohl said they also want to create an evaluation platform to help physicians with their prescribing practices.

“We hope eventually to be able to prevent many of these events from even happening in the first place,” she said.

Photo: Wikimedia Commons