Published in the July 2005 issue of Today’s Hospitalist
New research on adverse drug events that patients experience after they leave the hospital sheds light not only on the nature of these problems, but some of the challenges that hospitalists may face in trying to prevent or minimize adverse events.
The study, which was published in the April 2005 issue of the Journal of General Internal Medicine, found that one in nine patients discharged from a Boston teaching hospital experienced an adverse drug event. Those events were significant in 71 percent of patients who experienced an adverse event, serious in 13 percent and life-threatening in 16 percent.
After examining those events, researchers concluded that 27 percent were preventable and likely due to an error, and that 33 percent were ameliorable. The study defined non-preventable events as ameliorable if someone in the health care system could have limited their impact by taking some action. (An example is warning a patient about a drug’s potential side effects and giving instructions on how to react.)
Many of the study’s findings will come as little surprise to hospitalists. The six classes of drugs that accounted for 87 percent of all events, for example, include well-known drugs like anti-infectives, corticosteroids and cardiovascular drugs. In addition, researchers found that the more medications patients took, the greater their risk of experiencing an adverse event.
When they took a closer look at adverse events, however, researchers uncovered some interesting information about what may cause “or exacerbate “drug problems after discharge. As a result, the study may give hospitalists some simple strategies to help avoid post-discharge problems with drugs.
Breakdown in monitoring
While a study of adverse drug events may evoke images of severe problems like dangerous drug interactions, that kind of mistake wasn’t a common cause of problems in this study. Alan J. Forster, MD, a hospitalist and scientist at the Ottawa Health Research Institute and lead author of the study, says that most adverse events were instead due to the known pharmacologic activity of the drugs prescribed by physicians.
Adverse events studied by researchers; for example; included gastrointestinal or cutaneous complications of anti-infective agents; hyperglycemia and neuropsychiatric complications of corticosteroids; wheezing in patients who received a beta-blocker; and constipation in patients who received narcotics.
These may not be life-threatening events, but Dr. Forster says the fact that they are so common “and often fairly preventable “makes them significant, particularly for hospitalists.
Researchers found that in many cases, for example, the health system failed to provide any drug monitoring after discharge, which directly led to an adverse event. One patient was sent home on potassium supplements and spironolactone “but without instructions to monitor his electrolytes. Less than two weeks later, he was back in the hospital with dangerous levels of potassium.
Ameliorable events
But an even more common cause of drug problems, particularly for events that were defined as ameliorable, was a failure to warn patients about a drug’s side effects.
One asthmatic patient, for example, was sent home on beta-blockers but wheezed and coughed for weeks before ever talking to a cardiologist. The problem? No one had told him what to do if he experienced those side effects, so he suffered in silence before seeing a doctor.
Dr. Forster acknowledges that many of the side effects uncovered in his study are not preventable, but he says the research raises questions about how well physicians are preparing patients to deal with potential problems. While 83 percent of patients in the study said that someone had discussed their medications before discharge and 90 percent received a written list of medications, only 62 percent could recall being warned about possible side effects.
When patients weren’t prepared for a side effect, it sometimes led to a domino effect. “Not only did the adverse event happen,” Dr. Forster explains, “but other related events took place. The patient’s blood sugar would rise, which may be nonpreventable, but the patient would then not do anything about it, get dehydrated and then wind up back in the hospital.”
“If someone had talked to patients about how to increase their insulin or make sure that their fluid intake was good or call someone if they had problems controlling their glucose,” he says, “they could have remedied the situation.”
Nonlinear numbers
Some other surprising conclusions surfaced when researchers analyzed the numbers of adverse drug events experienced by patients.
Few physicians will be surprised by the study’s finding that the more medications a patient took, the greater their risk of an adverse event. On closer inspection, however, researchers discovered that the increased risk was not linear, but increased dramatically once patients were taking more than 11 medications.
And when the study examined adverse events throughout the entire study population, it found that most drugs posed relatively little risk on their own. For every 100 drugs prescribed, in fact, researchers the found an average of only one adverse event.
But that figure is balanced by the fact that patients in the study left the hospital taking an average of eight medications. While the per-drug risk may be low, patients’ cumulative risk is actually fairly significant.
Those results put hospitalists in something of a quandary. While each drug you prescribe likely has a fairly low risk of causing an adverse event, most patients are taking so many medications that their overall risk of experiencing some sort of problem is significant. Predicting which drug will be the one that causes a problem, however, is a bit like looking for a needle in a haystack.
“Every prescription that you write is low risk,” Dr. Forster says, “but you write lots of prescriptions. How do you predict which prescription is going to cause the problem?”
Areas of interest
Dr. Forster says that his research provides some clues. The study, for example, ranked the risk of an adverse event by drug classes. The risk for a problem was greatest when corticosteroids, anticoagulants, anti-infective agents, analgesic agents and cardiovascular medications were prescribed.
The study also found that drug events are typically due to new medications, which gives hospitalists another area to focus on. All but one of the events recorded by the study, in fact, was due to a newly prescribed mediation or a modification of an existing drug.
Based on those results, Dr. Forster suggests that hospitalists focus on any new drug that is added to a patient’s regiment, agents in one of the six high-risk groups described above, and in patients who are taking many different medications.
“When the patient is taking more than 10 different drugs or is taking a drug that we know raises the risk of an adverse drug event,” he says, “hospitalists need to stop and think about the potential of an adverse drug event and what they can do to stop that from happening.”
“You don’t want to talk about the top 10,” he adds. “You want to talk about the two high-risk drugs and maybe pay particular attention to the agent the patient just started taking. If the person has been on an ACE inhibitor for two years, you probably don’t have to spend that much time talking about the drug. Talk about the warfarin you just started.”
