ED Visits for Adverse Drug Reactions Common and Rising

Marcia Frellick

November 22, 2016

Four of every 1000 individuals will be treated in an emergency department (ED) for an adverse drug reaction each year, and more than a quarter of them will be hospitalized, a new study has found.

Nadine Shehab, PharmD, MPH, from the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues published their findings online November 22 in JAMA.

The researchers examined ED visits for adverse drug events in the United States during the period 2013 to 2014 as well as changes in ED visits for adverse drug events since the period 2005 to 2006, using a nationally representative sample from 58 EDs participating in the National Electronic Injury Surveillance System–Cooperative Adverse Drug Event Surveillance project.

On the basis of 42,585 cases, they estimate 4.0 (95% confidence interval [CI], 3.1 - 5.0) ED visits for adverse drug events occurred per 1000 people a year in 2013 and 2014; 27.3% (95% CI, 22.2% - 32.4%) of those cases resulted in hospitalization.

Adverse drug events increased substantially between the two study periods among the elderly. In 2013-2014, 34.5% (95% CI, 30.3% - 38.8%) of ED visits for adverse drug events occurred among adults aged 65 years or older, compared with 25.6% (95% CI, 21.1% - 30.0%) in 2005-2006.

Medications that should always be avoided in older adults, according to Beers criteria, were associated with 1.8% (95% CI, 1.5% - 2.1%) of such visits to the ED. Medications that are potentially inappropriate in older adults according to those same criteria were responsible for 3.4% of estimated ED visits for adverse drug events.

Involved Drug Classes Same as 10 Years Ago

The most common drug classes involved in ED visits remained the same for the two study periods: anticoagulants, antibiotics, diabetes drugs, and opioids.

Among children aged 5 years and younger, antibiotics were the most common cause of ED visits for adverse drug reactions; for those aged 6 to 19 years, antibiotics were most frequently implicated, followed by antipsychotics.

"The American Psychiatric Association currently warns against using antipsychotics as first-line therapy in children and adolescents for conditions other than psychotic disorders; however, antipsychotic prescribing has increased sharply during the last 2 decades," the researchers write.

Among older adults (aged 65 years or older), anticoagulants, diabetes agents, and opioids were the cause of 59.9% of ED visits for adverse drug events.

Among anticoagulant adverse drug events in the elderly, warfarin was implicated in 85.7% (95% CI, 82.8% - 88.6%) of the ED visits.

Given these findings, it may be beneficial to focus medication safety efforts on specific populations, such as children and adolescents and the elderly, the authors say.

"Clinically Significant Adverse Events"

Drug classes that were the most frequently implicated were also those responsible for "clinically significant adverse events," the researchers write.

"There was documented hemorrhage in an estimated 79.4% (95% CI, 75.2% - 83.6%) of ED visits for adverse drug events involving anticoagulants alone; moderate to severe allergic reactions in an estimated 18.2% (95% CI, 15.4% - 21.0%) of ED visits for adverse drug events involving antibiotics alone; hypoglycemia with moderate to severe neurological effects (eg, loss of consciousness or altered mental status) in an estimated 47.6% (95% CI, 39.4% - 55.7%) of ED visits for adverse drug events involving diabetes agents alone; and moderate to severe neurological effects in an estimated 33.9% (95% CI, 29.1% - 38.7%) of ED visits for adverse drug events involving opioid analgesics alone," they explain.

In an accompanying editorial, Chad Kessler, MD, MPH, from Durham VA Medical Center, in North Carolina, and colleagues write that gains in life expectancy are being eroded partially by the misuse of prescription medications.

"Even though this study specifically excluded ED visits for drug withdrawal, therapeutic failure, occupational exposure, intentional overdose, and recreational drug use, Shehab et al still found an estimated 1.3 million ED visits for [adverse drug events], nearly a 10% increase from 2005-2006," they write.

EDs in Veterans Health Administration medical centers, for which there is a nationwide medical record system, and other integrated care models were not included in this study, but they may provide lessons for ways to reduce these events, the editorialists write.

In fragmented systems, clinicians unfamiliar with patients or their medications are often reluctant to discontinue medications, and even when they are familiar with the patient, it is difficult to coordinate medications for multiple morbidities.

Concerns about adverse drug events may not be fully addressed in acute settings such as the ED, where there is little time and there are barriers to communicating with the patient's primary care team.

"Collaboration is needed among physicians and other health professionals in primary care, specialty care, pharmacy, and emergency medicine to answer these questions in the quest for safer models of patient care," the editorialists write.

The study was funded by the US government; the editorial was supported by the National Heart, Lung, and Blood Institute. The authors and editorialists have disclosed no relevant financial relationships.

JAMA. Published online November 22, 2016.

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